WO2019026251A1 - Titanium block, method for producing same, and titanium slab - Google Patents

Abstract

A plate-form titanium block having a thickness of 7-80 mm, wherein: the chemical composition comprises, in percentage by mass, 0.01-0.5% of O, 0.01-5% of Fe, 0-8% of Al, 0-5% of Sn, 0-12% of Zr, 0-15% of Mo, 0-2% of Ta, 0-22% of V, 0-2% of Nb, 0-1% of Si, 0-10% of Cr, 0-0.1% of Cu, 0-1% of Co, 0-1% of Ni, 0-0.5% of platinum group elements, 0-0.2% of REM, 0-3% of B, 0-0.2% of N, 0-2% of C, and 0-0.013% of H, the balance being titanium and unavoidable impurities; the difference ΔC between the maximum value CMAX and the minimum value CMIN of the measured values of each of the elements is less than 0.2CMIN or less than 0.04%; and the metal structure has an equivalent circle average crystal grain diameter that is 10 mm or less, and equal to or less than half the thickness, in a central portion along the thickness direction of the titanium block. This titanium block can be produced inexpensively.

Description

Titanium mass and method for producing the same, and titanium slab

The present invention relates to a titanium mass and a method for its manufacture as well as a titanium slab.

Since titanium materials are metal materials excellent in corrosion resistance, they are used in heat exchangers and various chemical plants using seawater. In addition, since titanium materials are smaller in density than carbon steel and excellent in specific strength (strength per unit weight), they are often used in aircraft fuselages. In addition, by using titanium material for land transportation equipment such as automobiles, since the equipment itself becomes lightweight, improvement in fuel consumption is expected.

However, titanium materials are manufactured by a large number of processes which are more complicated than steel materials. The following is a typical process.

(A) Smelting and smelting process: After chlorinating titanium oxide which is the raw material to titanium tetrachloride, and reducing with magnesium or sodium, a massive, sponge-like metallic titanium (hereinafter referred to as "sponge titanium") is produced Process.

(B) Melting step: A step of press-forming sponge titanium to form an electrode and melting it in a vacuum arc melting furnace to produce an ingot.

(C) Forging process: A process of forging a ingot hot and manufacturing a slab (a hot rolled material), a billet (a material such as hot extrusion or hot rolling), and the like.

(D) Hot working process: A process of heating a slab or billet and hot rolling or extruding to produce a plate or a round bar or the like.

(E) Cold working step: A step of further cold-rolling a plate or a round bar to produce a thin plate, a round bar, a wire or the like.

Titanium materials are very expensive because they are manufactured by such many processes. For this reason, titanium materials are hardly applied to land transportation equipment such as automobiles. In order to promote the use of titanium materials, it is necessary to improve the productivity of the manufacturing process. Efforts have been made to omit the manufacturing process of titanium material as a technology to cope with this problem.

Since VAR (vacuum arc melting) can produce only cylindrical titanium ingots, for subsequent hot rolling to form thin plates, the cylindrical titanium ingots are hot forged to form a rectangular solid. Of titanium, ie a titanium slab.

On the other hand, in electron beam melting and plasma melting, molten titanium is held in a container (cold hearth) and then injected into molds of various shapes. For this reason, by using a cuboid mold, a titanium ingot in the form of a direct slab can be obtained, and the forging process can be omitted (direct slab casting method). The melted titanium begins to solidify from the surface layer of the titanium ingot in contact with the mold, and the central portion of the thickness is eventually solidified to obtain a titanium ingot. At the same time, the titanium ingot is pulled downward from above, and gradually solidifies upward from below.

Patent Document 1 discloses an invention for producing a titanium ingot by omitting the melting step. This titanium ingot (slab) is manufactured by compression molding porous titanium (sponge titanium) into cast mass and melting the surface under vacuum, and the inside is porous titanium and the entire surface is densely packed. Is coated with titanium. According to the invention disclosed in Patent Document 1, since a slab-shaped titanium ingot is manufactured using sponge titanium or a compression-formed body thereof, a thin-walled slab can be manufactured.

Patent Document 2 discloses an invention of manufacturing a titanium alloy round bar by adding copper powder, chromium powder or iron powder to titanium alloy powder, enclosing it in a capsule made of carbon steel, heating and extruding hot. It is done. In Patent Document 3, titanium powder or titanium alloy powder containing hydrogen is filled in a capsule, dehydrogenated by heating while reducing pressure, and then hot-extruded to manufacture a titanium round bar or titanium alloy round bar The invention is disclosed. Patent Document 4 discloses an invention relating to a titanium material in which at least one selected from sponge titanium, titanium briquette and titanium scrap is filled in a packaging material formed of pure titanium material.

JP, 2015-45040, A JP, 2014-019945, A JP, 2012-041583, A International Publication No. 2016/056607

The direct slab casting method is an excellent method that can omit the forging step, but the slab thickness obtained is 100 mm or more, and usually about 200 mm to about 400 mm. Since the thickness of the slab is determined by the thickness of the mold, the thickness of the slab can be reduced by reducing the thickness of the mold.

However, when the thickness of the mold is smaller than 100 mm, when the molten titanium is injected from the cold heart into the mold, the molten titanium scatters out of the mold, or the molten titanium becomes uniform in the width direction of the mold from the injected portion. Problems such as not flowing into

Also, in order to obtain a titanium thin plate with a thickness of a few mm or less from a slab with a thickness of 100 mm or more, huge hot processing equipment is required because large processing must be performed, or It has to be processed repeatedly and is inefficient.

Furthermore, a slab with a thickness of 100 mm or more has a slow internal cooling rate due to its thickness, and crystal grains grow very large. For this reason, in order to obtain mechanical properties such as tensile properties required for the product, it is necessary to perform large processing to break coarse grains into fine particles. Because of its thickness, solidification segregation becomes large, and the difference between the surface layer and the central part of the slab is large. Moreover, in the length (up and down) direction of the titanium ingot, the thickness center portion above the slab finally solidified is particularly susceptible to solidification segregation and positive segregation Fe, Cr, Co, Cu, Ni, V, Si Etc. are concentrated.

In the direct slab casting method, since titanium melted in a vacuum chamber is held in a cold hearth, a part of titanium and auxiliary materials (alloy additive elements) volatilize and adhere to the wall of the chamber in a large amount. For this reason, the yield at the time of obtaining an ingot becomes bad. In addition, since it takes time to remove volatiles adhering to the chamber wall, the workability is poor. In the case of a titanium alloy containing an element (Al, Cu, Sn, etc.) that is more volatile than titanium, the content of the easily volatile element in the slab is less than the content of the titanium raw material. For this reason, the amount of volatilization of each element is predicted, and the amount corresponding to them is added to the titanium raw material in a larger amount.

However, the volatilization amount largely changes depending on the operation conditions such as the dissolution rate, the slab withdrawal rate, and the EB irradiation conditions. For example, the dissolution rate varies depending on the size and shape of the titanium raw material, and when the dissolution rate decreases, the amount of molten titanium flowing in the cold heart decreases and the amount of volatilization increases. The slab withdrawal rate is reduced at the beginning and end of casting, where the molten titanium in the cold hearth is low. During this time, the time of EB irradiation to the molten titanium in the mold becomes long, and the volatilization amount increases. The irradiation conditions can basically be made constant, but if an operation trouble occurs, it is necessary to reduce or stop the output, so the dissolution rate decreases or the dissolution stops. Lowering the output reduces the amount of volatilization. It is extremely difficult to predict and manage these operating conditions, and thus, component variations were inevitable in the longitudinal direction of the slab.

Since the inside of the titanium ingot disclosed by Patent Document 1 is granular sponge titanium, basically, only titanium ingot having the same chemical composition as sponge titanium can be obtained. In order to obtain a titanium ingot having a chemical composition different from that of sponge titanium, necessary elements must be added. For example, titanium oxide powder is added to increase titanium oxygen in order to increase strength, and Al-V alloy particles or Al particles are added to titanium sponge and mixed to form a Ti-6Al-4V alloy.

However, the sponge titanium and the additive element powder or particles do not easily become homogeneous because there is no subsequent dissolution step. In order to carry out solution heat treatment after hot working and achieve homogenization by diffusion of each element, it is necessary to carry out solution treatment for a vast amount of time, which is not practical. Therefore, in the invention disclosed by Patent Document 1, only a titanium ingot having a chemical composition equivalent to that of sponge titanium can be manufactured, and a titanium alloy ingot can not be manufactured.

Furthermore, when the as-cast surface is hot-rolled, the surface of the obtained titanium thin sheet is prone to the occurrence of a scaly surface defect. Since the titanium ingot disclosed in Patent Document 1 is obtained by melting and solidifying only the surface, the surface has a rough cast structure (coarse crystal grains). At the time of hot rolling in the next step, the coarse cast structure (coarse crystal grains) of the surface layer of the ingot causes an undulation on the surface of the ingot due to strong plastic anisotropy due to the difference in crystal orientation. It is because it becomes a surface defect.

According to the inventions disclosed in Patent Documents 2 and 3, it is possible to manufacture various titanium or titanium alloy round bars by using powders as raw materials and adding various elements as powders. Since this uses a powder finer than sponge titanium, a homogeneous round bar can be obtained even if the solution treatment after hot working is relatively short. However, in order to manufacture raw material powders, such as titanium powder, titanium alloy powder, and powder for alloy addition, effort and cost are required.

According to the invention disclosed in Patent Document 4, since the melting step and the forging step can be omitted, the titanium material can be obtained at low cost. However, since sponge titanium or the like is used as it is, as in the invention of Patent Document 1, only titanium ingots having the same chemical composition as sponge titanium can be manufactured, and a problem occurs that titanium alloy ingots can not be manufactured. Do.

In view of such circumstances, the present invention reduces the cost of titanium chunks for hot working or cold working, which are raw materials of titanium thin plates and titanium wires, particularly titanium chunks having various chemical compositions of thin thickness or small diameter. Intended to be manufactured by

MEANS TO SOLVE THE PROBLEM As a result of repeating earnest examination, in order to solve the said subject, the present inventors considered that a forging process could be abbreviate | omitted and that a titanium lump which can further simplify a hot-working process could be manufactured.

FIG. 1 is an explanatory view schematically showing a titanium briquette 1.

The raw material to be used is sponge titanium 1a which can be obtained relatively inexpensively manufactured by a usual process. Since the granular titanium sponge 1a remains as it is even if it is subjected to electron beam melting, the shape is not arranged, so as shown in FIG. 1, the titanium sponge 1a is compression-molded into a rectangular titanium briquette 1.

At this time, the auxiliary raw material 1c containing the elements (oxygen, Fe, Al, V, etc.) necessary to obtain a titanium mass having a necessary chemical composition is added to sponge titanium 1a and mixed, and then compression molding is performed. Get a briquette 1.

Since the titanium briquette 1 has the air gap 1d inside, after removing the air existing in the air gap 1d under reduced pressure, the electron beam dissolves a part (for example, about half) 2a in the thickness direction of the titanium briquette 1 Do.

FIG. 2 is an explanatory view schematically showing the titanium mass 2.

Thereafter, the titanium briquette 1 is inverted, and the remaining part (for example, about half) 2b in the thickness direction which has not been melted is similarly melted by the electron beam. The present inventors dissolve the titanium briquette 1 by evacuating the air gap 1d and dissolve the added auxiliary material 1c together with the sponge titanium 1a to be homogeneous, and as shown in FIG. It was found that it could be obtained.

At this time, in order to prevent the air bubbles from remaining in the titanium lump 2, the air present in the voids 1d between the sponge titanium 1a particles must be sufficiently removed. It has also been found that it is important to put the titanium briquette 1 before electron beam melting into a reduced pressure atmosphere as much as possible.

In order to melt and solidify a part of titanium briquette 1 by electron beam and also because the thickness of titanium mass 2 is thin, all raw materials are melted and then injected into a mold to solidify and cool as in the conventional melting process. The present inventors also found that the cooling rate after solidification is faster than the titanium material having a large thickness, and the crystal grains inside the titanium lump 2 are not coarsened.

Further, sponge titanium 1a is compression-molded into a cylindrical, prismatic or polygonal rod shape into titanium briquette 1, and similarly, electron beam melting is performed to form a columnar, prismatic or polygonal rod shape. It has also been found that a small diameter titanium block 2 can be obtained.

FIG. 4 is an explanatory view schematically showing the titanium slab 3.

Furthermore, in order to suppress surface defects during hot working, the titanium mass 2 obtained above is filled in a container (packaging material) 4 manufactured with a titanium plate 4a having the same chemical composition, and a packing material All joints 4 were welded to form a welded portion 5 to obtain a titanium slab 3 shown in FIG. The present inventors also found that this titanium slab 3 can be used as a titanium material for hot working.

The present invention is based on these novel findings and is as listed below.

(1) A plate of titanium having a thickness of 7 to 80 mm,
The chemical composition is in mass%,
O: 0.01 to 0.5%,
Fe: 0.01 to 5%,
Al: 0-8%,
Sn: 0 to 5%,
Zr: 0 to 12%,
Mo: 0 to 15%,
Ta: 0 to 2%,
V: 0 to 22%,
Nb: 0 to 2%,
Si: 0 to 1%,
Cr: 0 to 10%,
Cu: 0 to 0.1%,
Co: 0 to 1%,
Ni: 0 to 1%,
Platinum group element: 0 to 0.5%,
REM: 0 to 0.2%,
B: 0 to 3%,
N: 0 to 0.2%,
C: 0 to 2%,
H: 0 to 0.013%
The balance is titanium and impurities,
The difference ΔC between the maximum value C _MAX and the minimum value C _MIN of the measured values of each element is less than 0.2 C _MIN or less than 0.04%,
The metallographic structure is
The circle equivalent average crystal grain size at the central portion in the thickness direction of the titanium mass is 10 mm or less and half or less of the thickness of the titanium mass.
Titanium lumps.

(2) A titanium block having a cylindrical shape whose cross section perpendicular to the longitudinal direction is a circle having a diameter of 10 to 80 mm, or a columnar shape having a pentagon or more polygon having a circle equivalent diameter of 10 to 80 mm,
The chemical composition is in mass%,
O: 0.01 to 0.5%
Fe: 0.01 to 5%,
Al: 0-8%,
Sn: 0 to 5%,
Zr: 0 to 12%,
Mo: 0 to 15%,
Ta: 0 to 2%,
V: 0 to 22%,
Nb: 0 to 2%,
Si: 0 to 1%,
Cr: 0 to 10%,
Cu: 0 to 0.1%,
Co: 0 to 1%,
Ni: 0 to 1%,
Platinum group element: 0 to 0.5%,
REM: 0 to 0.2%,
B: 0 to 3%,
N: 0 to 0.2%,
C: 0 to 2%,
H: 0 to 0.013%,
The balance is titanium and impurities,
The difference ΔC between the maximum value C _MAX and the minimum value C _MIN of the measured values of each element is less than 0.2 C _MIN or less than 0.04%,
The metallographic structure is
The cross section perpendicular to the longitudinal direction of the titanium block has a columnar structure extending in the direction from the surface toward the center, and the circle equivalent average grain size at the center position of the cross section is 10 mm or less and half or less of the diameter of the cross section Is
Titanium lumps.

(3) A packaging material having the same chemical composition as the titanium mass of (1) or (2) above,
(1) or (2) the titanium block filled inside the packing material,
The internal pressure of the packing material is 10 Pa or less
Titanium slab.

(4) A compression molding process for obtaining titanium briquettes by compression molding one or more selected from sponge titanium and titanium scrap and an auxiliary material containing an element necessary for adjusting the chemical composition,
The surface of the titanium briquette is irradiated with an electron beam under a reduced pressure of 1 Pa or less to melt all the titanium briquette to form a titanium mass.
The manufacturing method of the titanium lump of said (1) or (2).

(5) The melting step irradiates an arbitrary surface of the titanium briquette with an electron beam and melts a part in the thickness direction from the surface, and irradiates an electron beam to any other surface; Dissolving at least undissolved titanium briquettes;
The manufacturing method of the titanium lump of said (4).

ADVANTAGE OF THE INVENTION According to this invention, it is a raw material which can be used to manufacture a titanium thin plate or a titanium wire by hot working or cold working, Comprising: The titanium lump which has various chemical compositions can be manufactured at low cost.
The titanium mass according to the present invention is a thin slab of small or small thickness (square column (for example, plate-like), cylinder, polygonal column), and the processing rate at the time of manufacturing a titanium thin plate or rod may be small. It is possible to manufacture titanium thin plate and rod efficiently and inexpensively.
Since the titanium mass of the present invention is a thin plate-like or small-diameter columnar titanium mass, the thickness central portion (plate-like titanium mass) or central portion in a cross section perpendicular to the longitudinal direction (columnar titanium mass) The grain size of is small and solidification segregation is small.
The titanium slab which filled the titanium lump which concerns on this invention in the packing material which consists of titanium board | plate materials can suppress generation | occurrence | production of the surface defect at the time of hot processing.
According to the manufacturing method of the present invention, it is possible to stably obtain a titanium ingot of a target component simply by adjusting the irradiation condition of the electron beam to a constant value.

FIG. 1 is an explanatory view schematically showing an example of a titanium briquette. FIG. 2 is an explanatory view schematically showing an example of a titanium mass. FIG. 3 is an explanatory view schematically showing another example of a titanium mass. FIG. 4 is an explanatory view schematically showing an example of a titanium slab. FIG. 5 is an explanatory view schematically showing another example of a titanium slab. FIG. 6 is a schematic view showing a sample for analysis.

The raw materials, titanium briquettes, titanium lumps, and titanium slabs used in the present invention will be sequentially described with reference to the accompanying drawings. In the following description, “%” relating to the chemical composition means “% by mass” unless otherwise noted.

FIG. 1 is an explanatory view schematically showing a titanium briquette 1, FIG. 2 is an explanatory view schematically showing a titanium block 2, and FIGS. 4 and 5 schematically show titanium slabs 3 and 30. FIG.

As shown in FIG. 1, titanium briquette 1 contains one or more of sponge titanium 1a and titanium scrap 1b, and elements necessary for achieving the function as a final product (for example, oxygen, Fe, Al, V, etc.) The secondary raw material 1c is mixed and obtained, for example, by compression molding into a rectangular parallelepiped shape.

1. Raw Material of Titanium Briquette 1 First, the raw material of titanium briquette 1 will be described. The raw material of titanium briquette 1 contains at least one of sponge titanium 1a and titanium scrap 1b, and contains auxiliary raw material 1c which selectively contains various elements.

(1-1) Size of Sponge Titanium When sponge titanium 1a is used as a raw material of titanium briquette 1, one manufactured by a smelting process such as the conventional Kroll method can be used. Since the sponge titanium 1a obtained in this smelting process is usually a large mass having several tons, it is desirable to use one which is crushed into particles as in the conventional process.

The size of sponge titanium 1a is 1 mm or more and 25 mm or less in average particle diameter (however, when used for a plate-like titanium block, the thickness is equal to or less than that of a titanium block, and when used for a polygonal columnar or cylindrical titanium block) titanium Preferably less than or equal to the diameter of the mass. When the average particle size is less than 1 mm, it takes time to crush and a large amount of fine dust is also scattered, resulting in a reduction in production efficiency. On the other hand, if the average particle size is larger than 25 mm, there is a limit to the range in which the titanium briquette 1 can be dissolved by irradiation with the electron beam in the subsequent step, so there is a possibility that it can not be dissolved uniformly with the secondary material 1c.

(1-2) Chemical Composition of Sponge Titanium Sponge titanium 1a is a raw material of titanium block 2, and in addition to titanium, oxygen, iron, nitrogen, carbon, hydrogen, chlorine, magnesium and the like are contained. Specifically, oxygen 0.40% or less, iron 0.50% or less, nitrogen 0.05% or less, carbon 0.08% or less, hydrogen 0.013% or less, chlorine 0.10% or less, magnesium 0. 10% or less is illustrated.

It is desirable that these amounts be equal to or less than the amount required for the titanium mass 2. If the amount of elements other than titanium contained in the sponge titanium 1a is equal to the amount required for the titanium mass 2, the sponge titanium 1a can be used as it is. When the amount of elements other than titanium contained in the sponge titanium 1a is smaller than the amount of elements other than titanium required for the titanium block 2, it is compensated by adding the auxiliary material 1c of the necessary amount of the chemical composition. Good.

If the amount of elements other than titanium contained in the sponge titanium 1a is larger than the amount of elements other than titanium required for the titanium block 2 and the amount of the sponge titanium 1a is smaller than the amount required for the titanium block 2, Dilute the elements other than titanium appropriately by mixing with other sponge titanium with a small amount of elements. Thereby, the target titanium lump 2 can be obtained. However, when the amount of elements other than titanium of the sponge titanium 1a is too large, it can not be used because it can not be diluted.

Next, titanium scrap 1b that can be used as a raw material will be described.

Titanium scrap 1b includes scraps that do not become products in the manufacturing process of titanium materials, titanium chips generated when cutting and grinding to make titanium materials into product shapes, and unnecessary after use as products It is a titanium material etc. which became.

(1-3) Size of titanium scrap The size of titanium scrap 1b is, similarly to sponge titanium 1a, 1 to 25 mm in average particle diameter (however, the thickness of titanium lump when used for plate-like titanium lump) Or less, when it is used for a polygonal columnar or cylindrical titanium mass, it is desirable that the diameter is equal to or less than the diameter of the titanium mass. When the average particle size is less than 1 mm, it takes time to crush and a large amount of fine dust is also scattered, resulting in a reduction in production efficiency. On the other hand, if the average particle size is larger than 25 mm, there is a limit to the range in which the titanium briquette 1 can be dissolved by irradiation with the electron beam in the subsequent step, so there is a possibility that uniform dissolution with the added auxiliary material 1c can not be achieved.

The titanium scrap 1b may be filled in the mold as it is, but titanium chips having a low bulk density or the like may be pre-compressed to increase bulk density in order to be filled more efficiently or more. Alternatively, it may be filled after mixing with sponge titanium 1a.

(1-4) Chemical composition of titanium scrap When titanium scrap 1b is mixed with sponge titanium 1a, JIS 1 type, JIS 2 type, JIS 3 type or JIS 4 type of the same type as the sponge titanium 1a concerned (JIS H 4600 (2012) titanium And titanium alloy-plates and strips). The titanium scrap 1 b may be of the same type as the target chemical composition of the titanium mass 2. Here, to have the same chemical composition specifically means to belong to the same standard of JIS. For example, when the chemical composition of sponge titanium 1a belongs to JIS 1 type, the titanium scrap 1b to be mixed may also be a chemical composition belonging to JIS 1 type. Alternatively, if titanium block 2 having a chemical composition belonging to JIS 2 is to be obtained, even if sponge titanium 1a has a chemical composition belonging to JIS 1 or titanium scrap 1b may have a chemical composition belonging to JIS 2; It may be set as a chemical composition other than this, and you may adjust insufficient oxygen and iron by adding the auxiliary material 1c.

Next, the auxiliary raw material 1c which can be used as a raw material will be described.

The auxiliary material 1c is added to one or more of sponge titanium 1a and titanium scrap 1b in order to obtain a titanium mass 2 having a target chemical composition. For example, titanium oxide is added when adding oxygen, electrolytic iron particles when adding iron, Al particles when adding Al, Al-V alloy particles when adding Al and V, Fe and Fe If it is desired to increase Mo, an Fe--Mo alloy is added as an auxiliary raw material 1c. The auxiliary raw material 1c may add only one type, or may add a plurality of types simultaneously.

(1-5) Size of Auxiliary Material The size of the auxiliary material 1c is preferably a powder or particles having an average particle diameter of 0.1 μm to 10 mm. In the case of powder having an average particle size of less than 0.1 μm, when transporting or mixing such fine powder, it is not possible to add a predetermined mass in order to be easily scattered and scattered around.

On the other hand, if the average particle diameter is larger than 10 mm, the range in which the titanium briquette 1 can be dissolved by irradiation with the electron beam in the subsequent step is limited, and therefore, it can not be uniformly dissolved with the sponge titanium 1a and titanium scrap 1b. Absent.

2. Titanium lump As shown in FIG. 2, titanium lump 2 is formed by compression molding sponge titanium 1a into a cylindrical, prismatic or polygonal rod shape into titanium briquette 1 and then melting the surface thereof, Columnar structures 2a and 2b are provided on the surface. The titanium mass 2 is a material for forming the titanium slab 3 by being filled in a container (packaging material) manufactured by a titanium plate material as described later. Alternatively, the titanium ingot 2 can be used as a hot working material (intermediate product). In this case, the titanium mass 2 is also referred to as a titanium slab, a titanium billet, or a titanium bloom depending on its size and shape.

(2-1) Chemical composition of titanium block The chemical composition of titanium block 2 is the chemical composition of titanium sponge 1a and / or titanium scrap 1b used as a raw material of titanium briquette 1 and the weight ratio thereof, and auxiliary raw material 1c to be added It depends on the chemical composition and its weight ratio. For this reason, the chemical compositions of sponge titanium 1a, titanium scrap 1b, and auxiliary raw material 1c are previously grasped by chemical analysis etc. so that the chemical composition of the target titanium block 2 can be obtained, and the chemical composition is determined according to the chemical composition. Determine the weight of each required ingredient. In addition, even if the element (for example, chlorine and magnesium) volatilized and removed by electron beam melting is contained in the titanium briquette 1, it is not contained in the titanium mass 2.

The chemical composition of the titanium mass of the present invention is, in mass%, O: 0.01 to 0.5%, Fe: 0.01 to 5%, Al: 0 to 8%, Sn: 0 to 5%, Zr: 0 to 12%, Mo: 0 to 15%, Ta: 0 to 2%, V: 0 to 22%, Nb: 0 to 2%, Si: 0 to 1%, Cr: 0 to 10%, Cu: 0 -0.1%, Co: 0-1%, Ni: 0-1%, platinum group element: 0-0.5%, REM: 0-0.2%, B: 0-3%, N: 0 To 0.2%, C: 0 to 2%, H: 0 to 0.013%, the balance being titanium and impurities.

Specifically, the platinum group element is one or more selected from Ru, Rh, Pd, Os, Ir and Pt, and the content of the platinum group element means the total content of the above elements. Moreover, REM is a general term for 17 elements in total of Sc, Y and lanthanoid, and the content of REM means the total amount of the above elements.

The content of the balance titanium in the titanium mass is preferably 70% or more. According to need, it may be 75% or more, 80% or more, 85% or more. The contents of Al, Sn, Zr, Mo, Ta, V, Nb, Si, Cr, Co, Ni, a platinum group element, REM and B are not essential, and the lower limit of each content is 0%. As necessary, the lower limit of each content of Al, Sn, Zr, Mo, Ta, V, Nb, Si, Cr, Co, Ni, a platinum group element, REM, and B is 0.01, respectively. %, 0.05%, 0.1%, 0.2%, or 0.5%.

The upper limit of O may be 0.4%, 0.3%, 0.2%, or 0.1%. The upper limit of Fe may be 3%, 2%, 1%, or 0.5%. The upper limit of the content of Al may be 5%, 3%, 2%, or 1%. The upper limit of the content of Sn may be 3%, 2%, 1%, or 0.5%. The upper limit of the content of Zr may be 10%, 8%, 5% or 2%. The upper limit of the content of Mo may be 12%, 9%, 4%, or 2%. The upper limit of the content of Ta may be 1%, 0.5%, 0.2%, or 0.1%. The upper limit of the content of V may be 18%, 15%, 10%, or 5%. The upper limit of the Nb content may be 1%, 0.5%, 0.2%, or 0.1%. The upper limit of the Si content may be 0.8%, 0.5%, 0.2%, or 0.1%. The upper limit of the content of Cr may be 8%, 5%, 2%, or 1%. The upper limit of the content of Co may be 0.8%, 0.5%, 0.2%, or 0.1%. The upper limit of the content of Ni may be 0.8%, 0.5%, 0.2%, or 0.1%. The upper limit of the content of the platinum group element may be 0.4%, 0.3%, 0.2% or 0.1%. The upper limit of N may be 0.1%, 0.05%, 0.03%, or 0.02%. The upper limit of Cu may be 0.8%, 0.5%, 0.2%, or 0.1%. The upper limit of C may be 1%, 0.5%, 0.2%, or 0.1%. The upper limit of the content of REM may be 0.1%, 0.05%, 0.03%, or 0.02%. The upper limit of the content of B may be 2%, 1%, 0.5%, or 0.3%.
The purpose of addition of each element is shown in Table 1.

The titanium mass 2 is preferably manufactured to satisfy the chemical composition range defined in various standards. Although there are also ASTM standards and AMS standards, the following mainly illustrates JIS standards as representative standards. The invention can be used to produce titanium or titanium alloys of these specifications.

(2-1-1) industrial pure titanium industrial pure titanium is an industrial pure titanium belonging to JIS class 1 to JIS class 4 (JIS H 4600 (2012) titanium and titanium alloy-plate and strip) adjusted with oxygen and Fe It is exemplified by titanium. Industrial pure titanium has better processability as the amount of oxygen and Fe is smaller, and the higher strength is as the amount of oxygen and Fe is larger. JIS class 1 includes C: 0.08% or less, H: 0.013% or less, O: 0.15% or less, N: 0.03% or less, Fe: 0.20% or less, balance Ti and impurities It is titanium having a chemical composition. With JIS class 2, C: 0.08% or less, H: 0.013% or less, O: 0.20% or less, N: 0.03% or less, Fe: 0.25% or less, balance Ti and impurities It is titanium having a chemical composition. With JIS 3 type, C: 0.08% or less, H: 0.014% or less, O: 0.30% or less, N: 0.05% or less, Fe: 0.30% or less, balance Ti and impurities It is titanium having a chemical composition. JIS 4 types are C: 0.08% or less, H: 0.015% or less, O: 0.40% or less, N: 0.05% or less, Fe: 0.50% or less, balance Ti and impurities It is titanium having a chemical composition.

(2-1-2) Corrosion-resistant titanium alloy The titanium-corrosion-resistant titanium alloy belongs to JIS 11 to JIS 23 including Pd, Ru, Ni, Co, etc. (JIS H 4600 (2012) titanium and titanium alloy-plate and strip) The alloy is exemplified. The corrosion resistant titanium alloy is excellent in corrosion resistance and crevice corrosion resistance.

(2-1-3) Titanium alloy Titanium alloy is Ti-1.5Al ((JIS 50 type (JIS H 4600 (2012) titanium and titanium alloy-plate and strip)), Ti-6Al-4V (JIS 60 type ( JIS H 4600 (2012) titanium and titanium alloy-plate and strip), Ti-3Al-2.5 V (JIS 61 (JIS H 4600 (2012) titanium and titanium alloy-plate and strip)), Ti-4 Al -22V (JIS 80 type (JIS H 4600 (2012) titanium and titanium alloy-plate and strip) etc. are exemplified.

Ti-1.5Al is excellent in corrosion resistance, and excellent in hydrogen absorption resistance and heat resistance.

Ti-6Al-4V has high strength and high versatility.

Ti-3Al-2.5V has good weldability and formability and good machinability.

Ti-4Al-22V is high in strength and excellent in cold workability.

According to the present invention, it is also possible to produce a titanium mass 2 having a chemical composition which is not defined in JIS other than the above. For example, as listed below.

With heat resistance Ti-6Al-2Sn-4Zr-2Mo-0.08Si, Ti-6Al-5Zr-0.5Mo-0.2Si, Ti-8Al-1Mo-1V, etc.
Low alloy and high strength Ti-1 to 1.5Fe-0.3 to 0.5O-0.01 to 0.04N etc., and Ti-6Al-2Sn-4Zr-6Mo etc. excellent in creep resistance,
High strength and good cold workability Ti-15V-3Cr-3Sn-3Al, Ti-20V-4Al-1Sn etc.
High strength and high toughness Ti-10V-2Fe-3Al etc.
Abrasion resistant Ti-6Al-4V-10Cr-1.3C etc. are illustrated.

(2-2) Shape of Titanium Mass The shape of the titanium mass 2 is preferably plate-like or columnar. The thickness of the plate-like titanium mass 2 is 7 to 80 mm. The upper limit of the thickness may be 70 mm, 60 mm, 50 mm or 40 mm. The columnar titanium block 2 may have a circular shape or a pentagon or more polygonal shape in a cross section perpendicular to the longitudinal direction. When the cross sectional shape is circular, the diameter of the cross section is 10 to 80 mm. The upper limit of the diameter of the cross section may be 70 mm, 60 mm, 50 mm or 40 mm. In the case of a polygon, the equivalent circle diameter is 10 to 80 mm. The upper limit of the circle equivalent diameter may be 70 mm, 60 mm, 50 mm or 40 mm. The equivalent circle diameter is the diameter of a circle corresponding to the area of the cross section.

The width of the plate-like titanium mass 2 need not be particularly defined. However, the lower limit may be equal to the thickness or 100 mm. The upper limit may be 100 mm, 500 mm, 1000 mm, or 2000 mm. The length of the titanium mass 2 need not be particularly defined. However, the lower limit may be equal to the plate width, diameter, or equivalent circle diameter, or may be 100 mm. The upper limit thereof may be 500 mm, 1000 mm, 3000 mm, 5000 mm, or 10000 mm.

Since the titanium briquette 1 has a void 1 d, the volume of the titanium block 2 produced from the titanium briquette 1 is smaller than that of the titanium briquette 1. For this reason, in order to obtain the titanium lump 2 of a desired size, it is necessary to determine the size of the titanium briquette 1 in consideration of the bulk specific gravity of the titanium briquette 1.

For example, in order to obtain a rectangular parallelepiped-shaped titanium block 2 (bulk specific gravity 4.5) having a thickness of 50 mm, a rectangular parallelepiped titanium briquette 1 (bulk specific gravity 3.2) having a thickness of 70 mm may be prepared. In order to obtain a cylindrical titanium block 2 (bulk specific gravity 4.5) having a diameter of 50 mm, a cylindrical titanium briquette 1 (bulk specific gravity 3.1) having a diameter of 60 mm may be prepared.

When the titanium mass 2 is plate-shaped, if the thickness is less than 7 mm, the thickness of the titanium briquette 1 is also thin and the strength is reduced. In this case, when the titanium briquette 1 is handled, such as movement or inversion, it may be broken or its corners may be chipped. On the other hand, if the thickness is larger than 80 mm, it is necessary to increase the melting depth of the titanium briquette 1 in the process of manufacturing a titanium block described later. In this case, the cooling rate after melting slows down and the crystal grains become coarse. Also, as in the conventional melting process, a huge output electron beam is required.

When the titanium mass 2 is in the shape of a column, the diameter (equivalent circle diameter in the case of a polygonal shape) is less than 10 mm, the diameter of the titanium briquette 1 is also small, and the strength is reduced. In this case, when the titanium briquette 1 is handled, such as movement or rotation, it breaks or breaks. On the other hand, when the diameter (in the case of a polygonal prism, the circle equivalent diameter) is larger than 80 mm, it is necessary to increase the dissolution depth of the titanium briquette 1 in the process of manufacturing a titanium block described later. In this case, the subsequent cooling rate becomes slow and the crystal grains become coarse. Also, as in the conventional melting process, a huge output electron beam is required.

(2-3) Size of Crystal Grains of Titanium Ingot When the titanium ingot 2 is plate-like and has a thickness of 7 to 80 mm, as shown in FIG. The columnar structures 2a and 2b extend in the thickness direction from the surface of the The central part in the sheet width direction and the longitudinal direction of the titanium block 2 and the central part in the thickness direction (area indicated by symbol A in FIG. 2, hereinafter referred to as the central area. The central area is the central part in the sheet thickness direction). The circle equivalent average crystal grain size in 10) is 10 mm or less and half or less of the thickness of the titanium mass 2. The titanium block 2 is a circular cylinder having a diameter of 10 to 80 mm, or a pentagon or larger polygon, and the circle equivalent diameter (the diameter of a circle whose cross-sectional area is the same as the cross-sectional area of the same polygon) is 10 to In the case of having a polygonal column shape of 80 mm, as shown in FIG. 3, in a cross section perpendicular to the longitudinal direction of the titanium block 2, it becomes a columnar structure 30 a extending in the direction (radial direction) from the surface to the center. Circle equivalent average crystal grain size of 10 mm or less at a central portion in the longitudinal direction and at a central position of the cross section (region indicated by symbol C in the figure, hereinafter referred to as central region), and half of cross sectional diameter of titanium block 2 It is below. Thereby, even when the processing rate is small when the titanium ingot 2 is hot-worked, the crystal grains can be easily divided, and the fine grains necessary for the product can be formed.

In addition, the titanium lump which irradiated and melt | dissolved the electron beam on the titanium briquette surface will solidify rapidly if irradiation stops, and will be rapidly cooled from the surface. For this reason, in a cross section perpendicular to the longitudinal direction of the titanium mass 2, crystal grains extend in a columnar shape in the direction perpendicular to the surface of the surface from the surface. Since the thickness of the titanium ingot (plate-like) is as thin as 7 to 80 mm as compared with the conventional ingot (usually 200 to 400 mm), the central region of the titanium ingot is also rapidly cooled. For this reason, the average grain size of the central region is 10 mm or less in equivalent circle diameter and half or less of the thickness. Similarly, since the diameter of the titanium ingot (columnar) is as short as 7 to 80 mm as compared with the conventional ingot, the central region of the titanium ingot is also rapidly cooled. Thereby, when the titanium ingot 2 is hot-worked, the crystal grains can be easily divided even with a small processing rate, and fine grains necessary for the product can be formed.

In FIG. 2, the lengths of columnar structures extending from the front and back sides are substantially the same. In other words, the lengths of crystals extending in a columnar shape from the front side and the back side are substantially the same. However, the length of the columnar structure from the surface side and the length of the columnar structure from the back side may be changed by largely changing the output of the electron beam irradiated from the front side and the back side. Also in this case, since the cooling rate near the center of the plate thickness is fast, the average grain size in the central region is 10 mm or less in equivalent circle diameter and half or less of the thickness. In FIG. 3, the columnar tissues extending from the cylindrical surface have the same length, but may not necessarily have the same length. Also in this case, since the cooling rate near the central region is fast, the average grain size of the central region of the cylinder is 10 mm or less in equivalent circle diameter and half or less of the diameter. Further, in FIG. 2, as a result of irradiating the side surface with the electron beam in the plate width direction, a columnar structure having a short length extends from the side surface in the plate width direction. Although irradiation of the electron beam to such a side is preferable, irradiation of the electron beam to the side is not essential as long as all the titanium briquettes 1 can be dissolved.

Although the lower limit of the equivalent circular diameter of the average crystal grain is not particularly limited, in order to reduce the crystal grain size in the titanium mass 2, it is necessary to make the thickness of the titanium mass 2 extremely thin. However, since it is limited to the thickness of the titanium mass 2 which can be manufactured, it is desirable that it is 0.5 mm or more.

The target crystal grains here are crystal grains of α phase in the case of industrial pure titanium and α-type titanium alloy, and crystal grains of β phase in the case of α + β two-phase titanium alloy and β-type titanium alloy. The crystal grain can be observed by visual observation or by magnifying with a loupe (magnifying glass) when a cross section perpendicular to the longitudinal direction of the titanium mass 2 is polished and then etching is performed with hydrofluoric acid. The number of crystal grains is determined by observing the crystals in the central region of the titanium block (the region located at half the thickness from the surface), and the observed area is divided by the number of crystal grains to obtain an average per crystal. The average crystal grain is calculated by calculating the area and determining the equivalent circle diameter. A circle is drawn in a region where 100 to 200 crystal grains are observed, the area of the circle is referred to as “observation area”, and the number of crystal grains observed in the circle is referred to as “the number of crystal grains”. If the average crystal grain size is small and it is difficult to observe visually, the image may be observed with an optical microscope and photographed, and the average crystal grain may be similarly determined from the photograph of the structure.

In the titanium block 2, a part of the titanium briquette is dissolved and sequentially solidified by an electron beam, and finally the entire titanium briquette is dissolved and solidified. Since the range of dissolution is limited to the portion irradiated with the electron beam, the amount of titanium lumps (titanium briquettes) dissolved is small. For this reason, concentration of elements other than titanium is small at the time of solidification, that is, solidification segregation is also small. For this reason, the fluctuation | variation by the place of the component of elements other than the added titanium is also restrained small. In addition, because titanium briquettes that are uniformly mixed in advance are partially melted sequentially, there is no melting unevenness of the titanium raw material, and if there is a problem that electron beam irradiation should stop by any chance, there is no problem if it is melted again from that position It does not occur. In this way, variations in the longitudinal component of the slab as in the direct slab casting method are also suppressed. That is, component fluctuation in the longitudinal direction of the titanium mass 2 is small, and its chemical composition is uniform.

The component analysis of the titanium lump 2 extract | collected the required quantity of the sample for analysis from the predetermined | prescribed position of the titanium lump 2, and performed it by one of the analysis methods listed below.
JIS H 1612 (1993) Determination of nitrogen in titanium and titanium alloys
JIS H 1614 (1995) Determination of iron in titanium and titanium alloys
JIS H 1617 (1995) Method of determining carbon in titanium and titanium alloys
JIS H 1619 (2012) Titanium and titanium alloys-Determination of hydrogen
JIS H 1620 (1995) Method for determining oxygen in titanium and titanium alloys
JIS H 1621 (1992) Method for determining palladium in titanium alloys
JIS H 1622 (1998) Titanium alloy-Determination of aluminum
JIS H 1624 (2005) Titanium alloy-Determination of vanadium
JIS H 1625 (2005) Titanium alloy-Determination of lanthanum, cerium, praseodymium and neodymium
JIS H 1630 (1995) Method of emission spectroscopy of titanium
JIS H 1631 (2008) Titanium alloy-X-ray fluorescence analysis method
JIS H 1632 (2014) Method of ICP emission spectrometry of titanium

FIG. 6 is a schematic view showing a sample for analysis. As shown in FIG. 6, as a sample for analysis, two places of 50 mm each (end area) from the front end and the rear end of the titanium lump 2 in the longitudinal direction and three equal divisions between them are divided equally. It was collected from a total of 5 locations at 3 locations in the middle position of the length. In the cross section of the titanium block 2, in the case of the rectangular block (slab) titanium block 2, the surface layer at the center in the width direction and the surface layer on the back surface have two sections; It was collected from two places on the surface. Furthermore, it was also sampled from the thickness center / diameter center at positions of 50 mm each from the longitudinal front and rear ends. In this way, samples for analysis were collected from a total of 12 places (the position of ● in FIG. 6) and analyzed, and the uniformity of the chemical composition was evaluated as follows.

If the difference ΔC between the maximum value C _MAX and the minimum value C _MIN of the content of each element is less than 0.2 C _MIN or less than 0.04%, it is evaluated as uniform. For example, in the case where the minimum value of the measured value of O is 0.04% and the maximum value is 0.05%, the difference ΔC (= 0.01%) is less than 0.04%, and is therefore uniform. It is evaluated. When the minimum value of the measured value of O is 0.30% and the maximum value is 0.32%, the difference ΔC (= 0.02%) is less than 0.2C _MIN (= 0.060%) As it is, it is evaluated as uniform. For example, in the case where the minimum value of the measured value of O is 0.03% and the maximum value is 0.05%, the difference ΔC (= 0.02%) is less than 0.04%, and is therefore uniform. It is evaluated. When the minimum value of the measured value of O is 0.30% and the maximum value is 0.35%, the difference ΔC (= 0.05%) is less than 0.2C _MIN (= 0.060%) As it is, it is evaluated as uniform.

3. Method for Producing Titanium Briquette The titanium briquette 1 is, as shown in FIG. 1, a molded body produced by compression molding the above-mentioned raw materials 1a and 1b and the auxiliary material 1c.

Since the sponge titanium 1a and the titanium scrap 1b are indeterminate, they can not be formed into a predetermined shape (a rectangular parallelepiped, a prism, a cylinder or the like) as it is. First, necessary sponge titanium 1a, titanium scrap 1b and auxiliary material 1c are put into a container and mixed. Since elements that are more likely to be volatilized than titanium are volatilized and reduced by electron beam irradiation in the latter stage, it is preferable to add an element in an amount that takes account of the volatilized amount beforehand.

The mixed raw materials are put into a mold having the same shape as the cross section of the titanium briquette 1 of a desired size, and compressed at a predetermined pressure to obtain the titanium briquette 1. The atmosphere at the time of compression molding is usually air at normal temperature (air).

The mixing means is not particularly limited, but it is desirable to adopt the means described below from the viewpoint of productivity and the like.

(A) A predetermined amount of sponge titanium 1a, titanium scrap 1b and auxiliary material 1c are charged into a mixing vessel.

(B) Stir so that sponge titanium 1a, titanium scrap 1b and auxiliary material 1c are uniformly mixed in the mixing vessel. As a method of stirring, the mixing container is rotated in the vertical direction, inclined at an angle of 20 to 70 ° from the horizontal and rotated in an oblique direction, the mixing container is vibrated in the vertical direction and the horizontal direction, etc. , Etc. to rotate the stirrer.

(C) The stirring time is 1 to 30 minutes depending on the size of the mixing vessel and the amount of sponge titanium 1a, titanium scrap 1b and auxiliary material 1c to be mixed. In consideration of productivity, it is desirable to determine the size and throughput of the mixing vessel so that uniform mixing can be performed in a few minutes.

(D) The mixed sponge titanium 1a, titanium scrap 1b and auxiliary raw material 1c are introduced from the mixing container into a press mold for compression molding to perform compression molding. Thereby, the sponge titanium briquette 1 in which the auxiliary material 1c is uniformly dispersed is obtained.

The size of the titanium briquette 1 may be appropriately determined according to the size of the titanium mass 2 and the size of the mold restricted by the compression processing apparatus.

4. Method for Producing Titanium Mass 2 The titanium mass 2 according to the present invention is obtained from the titanium briquette 1 manufactured above, as shown in FIG.

(4-1) Atmosphere The titanium briquette 1 is stored in a chamber, and the pressure in the chamber is reduced to 1 Pa or less. There are many voids 1d containing air (oxygen and nitrogen) inside the titanium briquette 1. If it is dissolved as it is, the titanium lump 2 will be oxidized and nitrided, or bubbles will remain, and it will be cracked or surfaced after hot working It causes the hemorrhoids. Therefore, the pressure is reduced to 1 Pa or less, and air is removed from the air gap 1 d inside the titanium briquette 1.

Although the lower limit of the pressure is not particularly limited, in order to extremely reduce the pressure in the chamber, the manufacturing cost is increased by improving the airtightness of the device or enhancing the evacuation equipment, etc. The lower limit of the pressure is preferably 1 × 10 ⁻³ Pa.

(4-2) Melting First, the titanium briquette 1 placed in the reduced pressure chamber is first irradiated with the electron beam on the upper surface, and then melted and solidified in order. Specifically, a part (for example, about half) 2a in the thickness direction of the titanium briquette 1 is irradiated with an electron beam to be sequentially melted and solidified. Since the range in which the electron beam can be melted is limited, the irradiation direction of the electron beam is moved, or the titanium briquette 1 is moved to irradiate the entire top surface of the titanium briquette 1 with the electron beam. Dissolve part 2a in the longitudinal direction and coagulate.

After that, the titanium briquette 1 is inverted, and the other side (side, end and back) is on the upper side, and the remaining part (for example, about half) 2b in the thickness direction not yet melted and solidified is similarly An electron beam is irradiated, and the entire area in the thickness direction of the titanium briquette 1 is dissolved and solidified sequentially to form a titanium mass. Thereby, a columnar structure extending in the thickness direction from the surface is obtained. In the case of the cylindrical titanium briquette 1 shown in FIG. 3, when melting the circumferential surface, it is preferable that a titanium block be irradiated with an electron beam while rotating around the axis of the cylinder. Thereby, in a cross section perpendicular to the longitudinal direction of the titanium mass, a columnar structure extending in a direction (radial direction) from the surface to the center is obtained. As described above, it is possible to dissolve and solidify all the titanium briquettes into titanium lumps by rotating the titanium briquettes at the time of dissolution (inversion of plate-like briquettes, rotation of cylindrical briquettes).

When the part 2 a in the thickness direction of the titanium briquette 1 is melted, the electron beam is adjusted so as not to melt the whole thickness direction or the whole diameter direction of the titanium briquette 1. When the entire thickness or the entire radial direction is melted (so-called electron beam penetrates), the molten titanium flows out from the lower side of the titanium briquette 1 and the desired shape can not be maintained.

For this reason, the melting depth of the titanium briquette 1 is made to be less than the thickness or the diameter of the titanium briquette 1. In general, it is desirable to dissolve the entire titanium briquette 1 by dissolving about half of the thickness or diameter and inverting or rotating to dissolve the other half.

In addition, since the size (width and length) of the titanium briquette 1 is limited, when obtaining a large titanium block 2, a plurality of titanium briquettes 1 may be arranged and melted and joined by an electron beam. In addition, it is preferable that the air removing process from the air gap 1d and the dissolving process (including dissolving after inversion) of the titanium briquette 1 with an electron beam be performed continuously under reduced pressure.

5. Titanium slab 3
Next, a titanium slab 3 and a titanium plate 4a using the titanium mass 2 according to the present invention will be described.

As shown in FIG. 4 or FIG. 5, the titanium slab 3 is obtained by adding the titanium blocks 2 and 20 obtained above to containers (packaging materials) 4 and 40 produced by titanium plate materials 4a and 40a having the same chemical composition. It fills up and welds all the joints of packing materials 4 and 40, and forms welding parts 5 and 50. The titanium slab 3 is also referred to as titanium billet or titanium bloom depending on its size and shape, and indicates a material for hot working (intermediate product).

The inside of the titanium slab 3 according to the present invention, which is covered with the titanium plate 4a, is vacuum, and the titanium slab 3 according to the present invention is stored.

As shown in FIG. 4, the titanium slab 3 according to the present invention is a titanium slab including a packing material 4 formed of a titanium plate 4 a and a titanium block 2 filled inside the packing material 4, The internal pressure of the material 4 is 10 Pa or less in absolute pressure, and the titanium plate 4 a is a processing material having the same chemical composition as the titanium block 2. As mentioned above, the titanium lump 2 is often manufactured to satisfy the chemical composition range defined in various standards. The chemical composition of the packaging material 4 is preferably in the same chemical composition range as the standard required for the titanium mass 2. That is, the same kind means that the packing material 4 and the titanium block 2 are in the same chemical composition range of the standard.

The titanium plate 4 a forming the packing material 4 will be described.

The titanium plate 4a is a titanium plate or a titanium tube produced by hot or cold plastic working such as rolling, extrusion, drawing, forging and the like. Since the titanium plate 4a is plastically worked, it has an advantage that the surface is smooth and the structure is fine (crystal grains are small).

(5-1) Thickness When the packing material 4 is a rectangular solid, although the thickness of the titanium plate 4a varies depending on the size of the packing material 4 to be produced, it is desirable that it be 0.5 mm or more and 30 mm or less. As the packaging material 4 is larger, strength and rigidity are required, so a thicker titanium plate 4a is used.

If it is less than 0.5 mm, the packaging material 4 may be deformed at the time of heating before hot working or may break at the beginning of hot working, which is not preferable. If it is thicker than 30 mm, the ratio of the titanium plate material 4a to the thickness of the titanium slab 3 increases and the filling amount of the titanium block 2 decreases, so the amount of processing the titanium block 2 is small and the manufacturing efficiency is poor and undesirable. The thickness of the titanium plate 4a is preferably thin for cost reduction, and may be 20 mm or less, 10 mm or 5 mm or less. The thickness may be 1 mm or more, 2 mm or more, or 3 mm or more in order to prevent breakage at the initial stage of hot working with certainty.

Furthermore, it is desirable that the thickness of the titanium plate 4 a be 3% or more and 25% or less of the thickness of the titanium slab 3. If the thickness of the titanium plate 4a is smaller than 3% of the thickness of the titanium slab 3, it will be difficult to hold the titanium block 2, and it will be greatly deformed at the time of heating before hot working, or the welded portion 5 of the packing material 4 will Or break.

On the other hand, when the thickness of the titanium plate 4a is thicker than 25% of the thickness of the titanium slab 3, there is no particular problem in manufacturing, but the ratio of the titanium plate 4a to the thickness of the titanium slab 3 becomes large. Since the filling amount of the lump 2 decreases, the amount of processing the titanium lump 2 is small, which is not preferable because the production efficiency is poor.

The same applies to the case where the packaging material 4 is a tube, and although the thickness of the titanium plate 4a differs depending on the size of the packaging material 4 to be produced, it is desirable that the thickness of the tube be 0.5 mm or more and 30 mm or less. Furthermore, as in the case of the rectangular parallelepiped, it is desirable that the thickness of the titanium plate 4 a be 3% or more and 25% or less of the diameter of the titanium slab 3. In addition, as shown in FIG. 5, a titanium block 2 is filled in a packing material 40 manufactured by bending a titanium plate material 40a into a hollow tube, and welding is performed on the end of the titanium plate material 40a to form a welded portion 50. Alternatively, the titanium slab 30 may be used.

(5-2) Chemical Composition The packaging material 4 needs to have the same chemical composition as the titanium block 2. Here, having the same chemical composition specifically means that it belongs to the same standard of JIS. For example, when the chemical composition of the titanium block 2 belongs to JIS 1 class, the packing material 4 also has the chemical composition belonging to JIS 1 class. Here, the specifications required for the titanium block 2 can be confirmed by documents at the time of trading or manufacturing. In addition, this standard can also be confirmed from the display of the surface of the titanium mass 2 in some cases. Within ± 30%, ± 20%, ± 15%, ± 10%, ± 8%, ± 5%, or ± 3% from the chemical composition (actual value) of titanium block 2 as necessary It may be within the limits.

Thus, by making the chemical composition of the packaging material 4 the same chemical composition as the titanium block 2, the surface layer and the inside of the titanium slab after processing can be made to have the same chemical composition, and as the titanium block as it is It can be handled.

(5-3) Size of Crystal Grain of Packaging Material 4 The titanium plate material 4a can adjust its crystal grain by performing appropriate plastic processing and heat treatment. The average crystal grain size of the titanium plate material 4 a used for the packaging material 4 is desirably 500 μm or less in equivalent circle diameter. Thereby, when the titanium slab 3 is hot-worked, it is possible to suppress surface wrinkles generated due to the difference in crystal orientation of coarse crystals.

Although the lower limit of the equivalent circle diameter of the average crystal grain is not particularly limited, in order to make the crystal grain diameter extremely small in the titanium plate 4a, it is necessary to increase the processing ratio at the time of plastic working. Because the thickness of the titanium plate 4a that can be used as is limited, the thickness is preferably 10 μm or more, and more preferably 15 μm or more.

The crystal grains targeted here are crystal grains of α phase in the case of industrial pure titanium or α-type titanium alloy, and crystal grains of β phase in the case of β-type titanium alloy. In the case of an α + β two-phase titanium alloy, it is an assembly of α phase (α colony). The α colony is an aggregate of α crystal grains of the same crystal orientation.

For the average crystal grains of industrial pure titanium, α-type titanium alloy, and β-type titanium alloy, the structure of the cross section including the thickness direction of the titanium plate material 4a constituting the packaging material 4 is observed with an optical microscope and photographed. From the structure photograph, average crystal grains of the surface layer (area from the surface to a depth of 0.3 mm) of the titanium plate material 4a are determined by a cutting method according to JIS G 0551 (2005).

The average crystal grain size (size of α colony) of the α + β two-phase titanium alloy is determined by the method described below using EBSD (Electron Backscatter Diffraction).

First, a test piece having a cross section including the thickness direction of the packaging material 4 made of the titanium plate 4a as an observation surface is collected, and then, a surface layer of the observation surface of the test piece (area from the surface to a depth of 0.3 mm) The measurement is performed using EBSD at a measurement interval of 2.3 μm and an acceleration voltage of 15 kV with a rectangular area of 2.4 mm long and 1.8 mm wide as a field of view. From the obtained measurement results, a PQ (pattern quality) map and a phase map are created from Kikuchi pattern analysis, and the α phase is extracted. In addition, Kikuchi pattern analysis excludes the beta phase and performs only for the alpha phase. Next, an α colony is determined with an angle difference of crystal orientation of adjacent EBSD measurement points being 15 ° or less, an area of each α colony is obtained from the measurement score of the α colony, and a circle equivalent diameter is calculated.

Next, the titanium slab 3 will be described.

(5-4) Shape The shape of the titanium slab 3 is not limited, but is determined by the shape of the manufactured titanium block. In the case of producing a titanium thin plate, the titanium slab 3 has a rectangular parallelepiped shape (slab). The thickness, width and length of the titanium slab 3 are determined by the thickness, width and length of the product, the amount of production (weight) and the like.

In the case of producing a titanium round bar, a wire rod or an extruded shape, the titanium slab 3 has a polygonal column shape (billet) such as a cylindrical shape or an octagonal column. The size (diameter, length) is determined by the thickness, width and length of the product, the amount of production (weight), and the like.

(5-5) Inside The titanium slab 3 is filled with titanium lumps 2. The titanium mass 2 can be packed one or more. There is a gap 6 between the titanium mass 2 and the packing material 4 and between the titanium masses 2. If there is air in the air gap 6, when heated before hot working, the filled titanium block 2 is oxidized or nitrided, and the titanium material obtained by working thereafter becomes brittle, and the necessary material The characteristics can not be obtained.

In addition, although filling with an inert gas such as Ar gas can suppress oxidation or nitriding of the titanium block 2 or the package 6, the Ar gas thermally expands during heating to push the packing material 4 apart, and a titanium slab 3 is deformed and can not be hot-worked.

For the above reasons, the space between the titanium block 2 and the packing material 4 and the space between the titanium blocks 2 must be reduced as much as possible. Specifically, the absolute pressure is preferably 10 Pa or less, more preferably 1 Pa or less.

If the internal pressure of the packaging material 4 is larger than 10 Pa, the titanium lump 2 and the packaging material 4 are oxidized or nitrided by the remaining air. The lower limit is not particularly limited, but in order to make the internal pressure extremely small, the manufacturing cost is increased by improving the air tightness of the device or enhancing the evacuation equipment, etc. Therefore, the lower limit of the internal pressure is 1 × 10. It is desirable to set to ^-3 Pa.

In addition, the internal pressure of the produced titanium slab 3 can be measured as follows. That is, by drilling holes in the titanium slab 3 in water or a vacuum chamber, the entire amount of gas (air) remaining inside is collected and its volume is measured, or its volume is determined based on the change in vacuum degree. It can be calculated. Moreover, the volume of the space | gap in the titanium slab 3 can also be grasped | ascertained by collect | recovering the water which penetrated inside and calculating | requiring the volume. By this method, it is possible to confirm that the internal pressure of at least the titanium slab 3 is 10 Pa or less.

(5-6) Depressurizing Method Next, a method of depressurizing the inside of the packaging material 4 and keeping it in vacuum will be described.

After the packing material 4 is filled with the titanium mass 2, the packing material 4 is sealed by reducing the pressure so as to be a predetermined internal pressure or less. Alternatively, the titanium plate members 4a may be partially joined and then depressurized and sealed. By sealing, there is no oxidation of the internal titanium lump 2 and the packing material 4 at the time of heating before hot working without invading air.

Although the sealing method is not particularly limited, it is preferable to weld and seal the titanium plate members 4a. In this case, the welded portion 5 is formed by welding all the joints of the titanium plate 4a, that is, welding all around. The method of welding the titanium plate 4a is not particularly limited, for example, arc welding such as Tig welding or MIG welding, electron beam welding, laser welding, or the like.

In the welding atmosphere, welding is performed under reduced pressure or in an inert gas atmosphere so that the inner surfaces of the titanium mass 2 and the packing material 4 are not oxidized or nitrided. When welding the joint of the titanium plate material 4 a finally, it is desirable to put the packing material 4 in a container (chamber) under reduced pressure and perform welding to keep the inside of the packing material 4 in a reduced pressure state.

In addition, after providing piping in a part of the packing material 4 in advance and welding the entire circumference in an inert gas atmosphere, the pressure is reduced to a predetermined internal pressure through the piping, and the piping is sealed by crimping etc. The inside of the material 4 may be depressurized. In this case, the piping may be installed at a position which does not become a problem at the time of hot working in the post process, for example, the rear end face.

(5-7) Processing The titanium block 2 and the titanium slab 3 which are thinner or smaller in diameter than the conventional one obtained as described above are hot-worked or cold-worked to form a desired shape. The method of processing varies depending on the shape of the titanium slab, but since both are thin or small in diameter, they can be easily processed to a desired size.

In the case of producing a titanium plate, the rectangular parallelepiped shape (slab) titanium mass 2 or titanium slab 3 is heated and hot-rolled to form a titanium plate. If necessary, as in the conventional process, after removing the oxide layer by pickling or the like, it may be cold-rolled and processed to be thinner.

When manufacturing a titanium round bar or wire rod, heat the cylinder 2 or titanium slab 3 in the shape of a cylinder or a polygonal column and perform hot forging, hot rolling or hot extrusion to form a titanium round rod or wire rod . Further, if necessary, as in the conventional process, after removing the oxide layer by pickling or the like, cold rolling or the like may be performed to make it further thin. In the case of manufacturing a titanium extruded material, a cylindrical or polygonal columnar titanium mass 2 or a titanium slab 3 is heated and hot-extruded to form titanium shapes having various cross-sectional shapes.

When the titanium ingot 2 is used, there may be a case where a scaly defect occurs on the surface of a plate, a round bar, or a section after hot working. In this case, the surface defect is removed by cutting, pickling or the like.

When the titanium slab 3 is used, the surface of the plate, the round bar, and the shape after hot working is good, and there is no need to clean the surface.

Next, examples of the present invention will be described.

As a titanium source of the raw material, sponge titanium (particle size = 0.25 mm to 19 mm) manufactured by Kroll method, oxygen content 0.03%, iron content 0.02%, nitrogen content 0.002%, A carbon content of 0.001% and a hydrogen content of 0.001% were used. In addition, as titanium scrap, JIS type 1 (oxygen content 0.04%, iron content 0.03%, nitrogen content 0.001%, carbon content 0.003%, hydrogen content 0.007%) A thin plate cut into a 20 to 30 mm square was used in part (see Nos. 11 and 12 in Table 1).

As secondary materials, titanium oxide powder, electrolytic iron, Pd particles, Al particles, Al-V alloy particles, Sn particles, Zr particles, Mo powder, Ta powder, Nb powder, Si powder, Cr particles, Co particles, Ni Grains, Ru powder, Mm (misch metal) powder, FeN powder, C powder, TiB ₂ powder were used as appropriate according to the target chemical composition of the titanium block. The Al—V alloy grains are alloys having an Al content of 30% and a V content of 70%. As Mm, a mixture mainly composed of La (lanthanum), Ce (cerium) and Nd (neodymium) was used.

Sponge titanium, titanium scrap and auxiliary materials were introduced into a stainless steel mixing vessel, and the mixing vessel was rotated up and down to mix the raw materials. The mixed raw materials were charged into a rectangular mold and compressed to form a rectangular parallelepiped titanium briquette. At this time, the porosity determined from the size and weight of the titanium briquette was 28 to 45%.

The obtained titanium briquettes were placed in a vacuum chamber, and the upper surface of the titanium briquettes was melted by an electron beam by 2-3 mm more than half the thickness of the titanium briquettes. The amount of dissolution (thickness) was previously determined for the relationship between the output of the electron beam and the thickness that can be dissolved, and from the result, the output of the electron beam was determined from the required thickness. After solidifying and cooling the top of the titanium briquette, the titanium briquette was inverted and the back was similarly melted.

Thus, the whole of the titanium briquette was dissolved and solidified to prepare a rectangular titanium block having a width of 300 mm and a length of 1200 mm and various thicknesses.

As a comparative example, titanium lumps were also produced, in which only the vicinity of the surface layer of the titanium lump was dissolved and the raw material was not dissolved therein (see No. 25 and 26 in Table 1). In each example, the thickness of the dissolved surface layer was 4 to 8 mm on each side.

The obtained titanium block was partially cut and subjected to component analysis to evaluate its homogeneity. The remaining titanium mass was hot-rolled into a rolled sheet with a thickness of 3.5 to 8.0 mm.

As a conventional example, a titanium ingot was obtained in an EB melting furnace having a cold hearth. That is, sponge titanium, titanium oxide, electrolytic iron, and Al particles were introduced into a cold hearth as raw materials, and the raw material was irradiated with an electron beam to obtain a titanium ingot in which molten titanium was injected into a mold having a thickness of 250 mm. The initial stage of dissolution was started at a dissolution rate of 0.35 ton / h, and the dissolution rate was gradually increased to dissolve at 0.75 ton / h in the constant part. Thereafter, the dissolution rate was gradually reduced to 0.2 ton / h at the end of dissolution, and the dissolution was completed to obtain a titanium ingot having a length of 1200 mm.

The crystal grain size at the center of the titanium mass was measured visually or using a metallurgical microscope. Moreover, the component analysis of the titanium lump extract | collected the required quantity of the sample for analysis from the predetermined | prescribed position of a titanium lump, and performed it by one of the analysis methods listed below.
JIS H 1612 (1993) Determination of nitrogen in titanium and titanium alloys
JIS H 1614 (1995) Determination of iron in titanium and titanium alloys
JIS H 1617 (1995) Method of determining carbon in titanium and titanium alloys
JIS H 1619 (2012) Titanium and titanium alloys-Determination of hydrogen
JIS H 1620 (1995) Method for determining oxygen in titanium and titanium alloys
JIS H 1621 (1992) Method for determining palladium in titanium alloys
JIS H 1622 (1998) Titanium alloy-Determination of aluminum
JIS H 1624 (2005) Titanium alloy-Determination of vanadium
JIS H 1625 (2005) Titanium alloy-Determination of lanthanum, cerium, praseodymium and neodymium
JIS H 1630 (1995) Method of emission spectroscopy of titanium
JIS H 1631 (2008) Titanium alloy-X-ray fluorescence analysis method
JIS H 1632 (2014) Method of ICP emission spectrometry of titanium

As a sample for analysis, two positions of 50 mm each (end area) from the front end and rear end of the titanium lump 2 in the longitudinal direction, and the middle position of each equal length of three equally divided between them It was collected from a total of 5 places of 3 places. In the cross section of the titanium block 2, in the case of the rectangular block (slab) titanium block 2, the surface layer at the center in the width direction and the surface layer on the back surface have two sections; It was collected from two places on the surface. Furthermore, it was also sampled from the thickness center / diameter center at positions of 50 mm each from the longitudinal front and rear ends. In this way, samples for analysis were collected from a total of 12 places (the position of ● in FIG. 6) and analyzed, and the uniformity of the chemical composition was evaluated as follows.

If the difference ΔC between the maximum value C _MAX and the minimum value C _MIN of the content of each element is less than 0.2 C _MIN or less than 0.04%, the uniformity is evaluated as good. For example, when the minimum value of the measured value of O is 0.04% and the maximum value is 0.05%, the difference ΔC (= 0.01%) is less than 0.04%, so the uniformity is good. It was evaluated as When the minimum value of the measured value of O is 0.30% and the maximum value is 0.32%, the difference ΔC (= 0.02%) is less than 0.2C _MIN (= 0.060%) Because of the presence, it was evaluated that the uniformity was good.

In addition, at the position of 50 mm from the front end and the rear end in the longitudinal direction, the crystal grain diameter at the thickness center was measured visually or using a metallographic microscope, and the average value was determined. The remaining titanium mass was hot-rolled into a plate with a thickness of 3.5 mm to 8 mm.

The production conditions of the titanium ingot in Example 1 are shown in Table 2, the produced titanium ingot is in Table 3, and the titanium material (rolled plate) produced by rolling the titanium ingot is summarized in Table 4.

As shown in Tables 2 to 4, no. The samples 1 to 8 were made of titanium chunks with various thicknesses by changing the thickness and porosity of the titanium briquette.

No. In the case 1), although a thin titanium block having a thickness of 5.7 mm was obtained when the thickness of the titanium briquette was as thin as 8 mm, rolling was not possible because some corners of the titanium briquette were broken.

No. of thickness other than this. 2 to 8 have a uniform chemical composition, the crystal grain size at the center of thickness of titanium block is as small as 0.8 to 7.8 mm, rolling can be performed without any problem, and part of the surface of rolled sheet Although surface wrinkles occurred, they were generally good. The surface wrinkles that partially occurred were removable by partial maintenance.

No. 8 to 10 are the cases of producing rolled sheets of JIS 1, 3 and 4 respectively. Reference numerals 11 and 12 are cases where JIS type 2 titanium scrap and JIS type 3 rolled sheet are manufactured using part or all of JIS type 1 titanium scrap.

In any case, these were homogeneous with little fluctuation of components, and a titanium block having a small central crystal grain size was obtained, and subsequent rolling could be performed without any problem. Although surface wrinkles were generated on part of the surface of the rolled sheet, it was generally good.

No. 13 to 24 are cases where Fe and various metal elements other than Fe are added as auxiliary materials. In any case, they are homogeneous with little fluctuation of components, and a titanium lump having a small central crystal grain size can be obtained, and subsequent rolling can be carried out without any problem, and surface wrinkles occur on part of the surface of the rolled sheet. Although it occurred, it was generally good.

No. 1 which is a comparative example. No. 25 and 26 produced titanium lumps in which the vicinity of the surface layer of titanium briquette was dissolved and the raw material (sponge titanium, auxiliary raw material) was not dissolved but left as it is. Since the thickness centers of these titanium lumps are not melted, the two centers of 50 mm each (end area) from the longitudinal front and rear ends remain as titanium briquettes. Therefore, it was omitted because analysis of the central part and measurement of the crystal grain size could not be performed. That is, the analysis evaluated the uniformity of a chemical composition from ten places extract | collected from the melt | dissolution titanium lump surface part.

In these titanium masses, additional elements other than titanium such as oxygen and Fe greatly fluctuated depending on the position of the titanium masses, resulting in inhomogeneous ingots. Furthermore, when this ingot was rolled, a large number of large surface cracks occurred because the deformation resistance at a high temperature largely differs with the inhomogeneity of this component. Therefore, it could not be used as a product.

No. 1 to No. The content of titanium in all of the twenty-six comparative examples and inventive examples was 70% or more. Further, carbon, nitrogen and hydrogen contained as impurities in sponge titanium and titanium scrap are contained in all of the comparative examples and the invention examples.

No. 1 is a conventional example. No. 27 is the result of dissolving industrial pure titanium (JIS type 2) by the conventional method, and since the slab is as large as 250 mm, the variation of the Fe component is large due to solidification segregation, and the crystal grain of thickness center is also as large as 13 mm. . In addition, a scaly surface wrinkle occurred frequently on the thin sheet after rolling. No. No. 28 is a result of melting the Ti-5Al-1Fe alloy, and since the slab is as large as 250 mm, the segregation of Fe causes large variation in the composition of Fe, and the crystal grain in the center of thickness also becomes as large as 12 mm. Further, due to the variation of the volatilization amount of Al, the variation of the component of Al is also large. In addition, a scaly surface wrinkle occurred frequently on the thin sheet after rolling.

No. 1 of the first embodiment. A titanium slab was manufactured using a 35 mm thick, 300 mm wide and 400 mm long titanium block manufactured in the same manner as No.4.

As a titanium packaging material, the same JIS 2 type material as that of a titanium block having a thickness of 1 to 20 mm was used.
When rolling a titanium slab, a pipe having a valve was fixed by Tig welding to one of the titanium packaging materials which was the side of the container not in contact with the rolling rolls. Keep the piping valve closed. After temporarily assembling five pieces of titanium packing material including a titanium packing material to which the pipe was welded to form a container, a titanium block was stored here and covered with the remaining titanium packing material. The temporarily assembled package was placed in a vacuum chamber and depressurized (vacuum) to a predetermined pressure, and then joints of the packaging material were welded with an electron beam all around the circumference to produce a titanium slab (Table 5 No.2, 3, 5 reference). A vacuum gauge was installed on the piping on the side of the manufactured titanium slab, and the valve was opened to measure the internal pressure. After measurement, the pipe was sealed between the titanium slab and the valve to cut off the valve.

Also, after assembling a titanium slab by TIG welding, pressure is reduced (vacuum) from the exhaust pipe provided on the titanium packing material until the inside of the titanium slab reaches a predetermined pressure, and then the exhaust pipe is sealed, The internal pressure of the titanium slab was adjusted.

These 37 to 75 mm thick titanium slabs were rolled to produce a rolled plate of 4.0 to 5.5 mm thick.

The results of Example 2 are summarized in Table 5 together with the test conditions.

As shown in Table 5, No. 1 in which the internal pressure of the titanium slab was 10 Pa or less. In 1 to 3, rolling was possible without problems, and the surface of the obtained rolled sheet was also good.

No. 1 in which the internal pressure of the titanium slab was 12 Pa. In No. 4, although the rolling was able to be performed without problems, the obtained rolled sheet was partially cracked and peeling occurred. Observation of the part where peeling occurred revealed that the titanium block and the surface of the titanium package were oxidized, and the two were not crimped.

Similarly, in the case of No. 1 of Example 1. A titanium slab was manufactured using a titanium block manufactured in the same manner as 14.

As the titanium packing material, the same Ti-5Al-1Fe material (the number is mass%) was used as the titanium lump of 10 mm in thickness. After temporarily assembling five pieces of titanium packaging material into a container, a titanium block was stored here and covered with the remaining titanium packaging material.

The temporarily assembled package was placed in a vacuum chamber and depressurized (vacuum) to a predetermined pressure, and then joints of the packaging material were welded by electron beams all around to produce a titanium slab (No. 5). ).

This titanium slab was rolled to produce a rolled plate of 5.0 mm thickness. Rolling was possible without problems, and the surface of the obtained rolled plate was also good.

As a titanium source of the raw material, sponge titanium (particle size = 0.25 mm to 19 mm) manufactured by Kroll method, oxygen content 0.04%, iron content 0.03%, nitrogen content 0.003%, A carbon content of 0.003% and a hydrogen content of 0.001% were used. In addition, as titanium scrap, JIS type 1 (oxygen content 0.04%, iron content 0.03%, nitrogen content 0.003%, carbon content 0.004%, hydrogen content 0.003%) A thin plate cut into a 20 to 30 mm square was used in part (see Nos. 10 and 11 in Table 3).

As secondary materials, titanium oxide powder, electrolytic iron, Pd particles, Al particles, Al-V alloy particles, Sn particles, Zr particles, Mo powder, Ta powder, Nb powder, Si powder, Cr particles, Co particles, Ni Grains, Ru powder, Mm (misch metal) powder, FeN powder, C powder, TiB ₂ powder were used appropriately according to the target component of the titanium block. The Al—V alloy grains are alloys having an Al content of 30% and a V content of 70%.

Sponge titanium, titanium scrap and auxiliary materials were introduced into a stainless steel mixing vessel, and the mixing vessel was rotated up and down to mix the raw materials. A predetermined amount of the mixed raw material was charged into a cylindrical mold, and compression molding was performed to manufacture three cylindrical titanium briquettes (length 300 mm). At this time, the porosity determined from the size and weight of the titanium briquette was 28 to 40%.

The obtained titanium briquettes were placed in a vacuum chamber by arranging three pieces in the longitudinal direction, and the peripheral surface of the titanium briquettes was melted by an electron beam by 2-3 mm more than half the diameter of the titanium briquettes. The amount of dissolution (diameter) was previously obtained by determining the relationship between the output of the electron beam and the thickness that can be dissolved, and from the result, the output of the electron beam was determined from the required thickness. The entire circumferential surface was melted and solidified while rotating the titanium briquette.

In this way, the entire titanium briquette was dissolved and solidified to produce a cylindrical titanium block having a length of 900 mm and a diameter of 9 to 78 mm. The uniformity of the chemical composition and the crystal grain size were evaluated in the same manner as in (Example 1).

As a conventional example, a titanium ingot was obtained in an EB melting furnace having a cold hearth. That is, sponge titanium, titanium oxide, electrolytic iron, and Al particles were introduced into a cold hearth as raw materials, and the raw materials were irradiated with an electron beam and injected into a molten titanium mold having a diameter of 600 mm. The initial stage of dissolution was started at a dissolution rate of 0.5 ton / h, and the dissolution rate was gradually increased to dissolve at 0.85 ton / h in the stationary part. Thereafter, the dissolution rate was gradually reduced to 0.3 ton / h at the end of dissolution, and the dissolution was completed to obtain a titanium ingot of 900 mm in length. The titanium ingot was forged to a diameter of 100 mm and further rolled to a round rod of a diameter of 30 mm after taking samples for analysis and samples for structure observation.

The production conditions of the titanium ingot in Example 3 are shown in Table 6, the produced titanium ingot is shown in Table 7, and the titanium material (round bar) produced by rolling the titanium ingot is shown in Table 8.

As shown in Tables 6 to 8, No. 1 as a comparative example. In No. 22, titanium lumps were produced by dissolving only the vicinity of the surface layer of the titanium lumps and not melting the raw materials inside.

The obtained titanium lump was subjected to chemical composition analysis by collecting a sample for analysis in the same manner as in Example 1, and the homogeneity thereof was evaluated by the same method as in Example 1. In addition, the crystal grain size at the center of the cross section perpendicular to the longitudinal direction was measured by visual observation or using a metallographic microscope at the central portion in the longitudinal direction. The remaining titanium mass was hot-rolled into round bars 8 to 18 mm in diameter.

No. in Table 6 to Table 8 1 to 6 are cases where titanium chunks of various diameters are manufactured by changing the diameter and porosity of titanium briquettes. When the diameter of the titanium briquette was as thin as 11 mm, although a thin titanium block having a diameter of 9 mm was obtained, it could not be rolled because it was broken at a part of the titanium briquette (No. 1). Titanium ingots of other diameters could be rolled without problems, and good round bars were obtained (No. 2 to 6).

No. 7 to 9 are cases where titanium lumps of JIS 1, JIS 3 and JIS 4 were manufactured. Parts 10 and 11 are cases where titanium scrap of part or all of JIS 1 type is used, and rolled sheets of JIS type 2 and JIS type 3 are manufactured. In each case, they were homogeneous with little variation in chemical composition, and a titanium mass having a small central crystal grain size was obtained, and subsequent rolling was also satisfactory, and a good quality bar was obtained.

No. 12 to 21 are cases where Fe and various metal elements other than Fe are added as auxiliary materials. In each case, a titanium block having a small variation in composition and a small central crystal grain size can be obtained, and subsequent rolling can be performed without problems, and a good quality round bar can be produced.

No. 1 which is a comparative example. In No. 22, a titanium lump having a diameter of 44 mm was produced by dissolving the vicinity of the surface layer of titanium briquette and leaving the raw materials (sponge titanium and auxiliary raw materials) undissolved therein. Since the thickness center of the titanium block is not melted, the two center portions at positions 50 mm away from the front end and the rear end in the longitudinal direction (end regions) remain as titanium briquettes. Therefore, it was omitted because analysis of the central part and measurement of the crystal grain size could not be performed. That is, the analysis evaluated the uniformity of a chemical composition from ten places extract | collected from the melt | dissolution titanium lump surface part.

The chemical composition of this titanium block was analyzed, and it was found that oxygen and Fe added as auxiliary materials greatly fluctuated depending on the position of the titanium block, resulting in a non-uniform ingot. Furthermore, when this ingot was rolled, a large number of large surface cracks occurred because the deformation resistance at a high temperature largely differs with the inhomogeneity of the chemical composition. Therefore, it could not be used as a product.

No. 1 to No. The content of titanium in all of the twenty-two comparative examples and inventive examples was 70% or more. Further, carbon, nitrogen and hydrogen contained as impurities in sponge titanium and titanium scrap are contained in all of the comparative examples and the invention examples.

No. 1 is a conventional example. No. 23 is the result of dissolving industrial pure titanium (JIS 2 type) by the conventional method, and since the ingot diameter is as large as 600 mm, the variation of the Fe component is large due to solidification segregation, and the crystal grain at the thickness center also becomes as large as 14 mm. The In addition, since surface cracking frequently occurred during forging, that portion had to be cut and removed, and the production yield significantly decreased. No. No. 24 is the result of melting Ti-6Al-4V alloy by the conventional method, and since the diameter of the ingot is as large as 600 mm, the variation of the composition of Fe is large due to solidification segregation, and the crystal grain of thickness center also becomes as large as 13 mm. Further, due to the variation of the volatilization amount of Al, the variation of the component of Al is also large. In addition, since surface cracking frequently occurred during forging, that portion had to be cut and removed, and the production yield significantly decreased.

According to the present invention, it is possible to produce thin-walled or small-diameter titanium lumps of various chemical compositions by omitting the conventional melting step and forging step, and also reducing the amount of processing in the next step of hot working. Titanium can be produced. For this reason, the energy required for manufacture can be reduced. Furthermore, by using a titanium slab, it is possible to omit the removal of defects generated on the surface of a titanium mass, the production yield is significantly improved, and the production cost can be significantly reduced.

Claims (5)

A plate of titanium 7 to 80 mm in thickness,
The chemical composition is in mass%,
O: 0.01 to 0.5%,
Fe: 0.01 to 5%,
Al: 0-8%,
Sn: 0 to 5%,
Zr: 0 to 12%,
Mo: 0 to 15%,
Ta: 0 to 2%,
V: 0 to 22%,
Nb: 0 to 2%,
Si: 0 to 1%,
Cr: 0 to 10%,
Cu: 0 to 0.1%,
Co: 0 to 1%,
Ni: 0 to 1%,
Platinum group element: 0 to 0.5%,
REM: 0 to 0.2%,
B: 0 to 3%,
N: 0 to 0.2%,
C: 0 to 2%,
H: 0 to 0.013%,
The balance is titanium and impurities,
The difference ΔC between the maximum value C _MAX and the minimum value C _MIN of the measured values of each element is less than 0.2 C _MIN or less than 0.04%,
The metallographic structure is
The circle equivalent average crystal grain size at the central portion in the thickness direction of the titanium mass is 10 mm or less and half or less of the thickness of the titanium mass.
Titanium lumps. A titanium block having a cylindrical shape whose cross section perpendicular to the longitudinal direction is a circle having a diameter of 10 to 80 mm, or a columnar shape having a pentagon or more with a circle equivalent diameter of 10 to 80 mm,
The chemical composition is in mass%,
O: 0.01 to 0.5%
Fe: 0.01 to 5%,
Al: 0-8%,
Sn: 0 to 5%,
Zr: 0 to 12%,
Mo: 0 to 15%,
Ta: 0 to 2%,
V: 0 to 22%,
Nb: 0 to 2%,
Si: 0 to 1%,
Cr: 0 to 10%,
Cu: 0 to 0.1%,
Co: 0 to 1%,
Ni: 0 to 1%,
Platinum group element: 0 to 0.5%,
REM: 0 to 0.2%,
B: 0 to 3%,
N: 0 to 0.2%,
C: 0 to 2%,
H: 0 to 0.013%
The balance is titanium and impurities,
The difference ΔC between the maximum value C _MAX and the minimum value C _MIN of the measured values of each element is less than 0.2 C _MIN or less than 0.04%,
The metallographic structure is
The cross section perpendicular to the longitudinal direction of the titanium block has a columnar structure extending in the direction from the surface toward the center, and the circle equivalent average grain size at the center position of the cross section is 10 mm or less and half or less of the diameter of the cross section Is
Titanium lumps. A packaging material having the same chemical composition as the titanium block according to claim 1 or 2;
The titanium lump according to claim 1 or 2, filled inside the packing material,
The internal pressure of the packing material is 10 Pa or less
Titanium slab. A compression molding process for obtaining titanium briquettes by compression molding one or more selected from sponge titanium and titanium scrap and an auxiliary material containing an element necessary for adjusting the chemical composition,
The surface of the titanium briquette is irradiated with an electron beam under a reduced pressure of 1 Pa or less to melt all the titanium briquette to form a titanium mass.
The manufacturing method of the titanium lump of Claim 1 or 2. The melting step irradiates an electron beam to any surface of the titanium briquette and melts a part in the thickness direction from the surface, and irradiates an electron beam to any other surface, at least unmelted. Dissolving the titanium briquettes of
The manufacturing method of the titanium lump of Claim 4.

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