WO2006132016A1 - Process for producing ingot - Google Patents

Abstract

A process for producing an ingot, in which even when a high-melting-point active metal, such as Ti, is contained, a large homogeneous ingot can be obtained economically. A large ingot is produced by casting an ingot from a melt obtained according to a cold crucible induction melting method, forming a consumable electrode from the ingot, re-melting the consumable electrode according to a vacuum arc re-melting method and casting the large ingot from the obtained melt.

Description

 Specification

 Ingot manufacturing method

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing an ingot, and more particularly to a method for manufacturing an ingot capable of economically obtaining a large and homogeneous ingot. For example, when mass-producing Ti and Ti alloy wrought materials, large and homogeneous ingots of several tons are required. The present invention relates to a method for producing an ingot which can economically obtain a large and homogeneous ingot even when it contains a high melting point active metal such as Ti. Background art

 [0002] Conventionally, as an ingot manufacturing method, in particular, a manufacturing method of an ingot containing an active metal having a high melting point such as Ti, a metal raw material is melted by a cold crucible induction melting method, and the molten metal is shaped into a bowl. There is a known method of inserting into an ingot (see, for example, Patent Document 1). As another manufacturing method, a method is known in which a consumable electrode made from a metal raw material is remelted by a vacuum arc remelting method, and the molten metal is poured into a mold to make an ingot! For example, see Patent Document 2).

[0003] The conventional method of melting a metal raw material by a cold crucible induction melting method has an advantage that the molten metal is uniformly mixed because the molten metal is mixed together. Therefore, by sampling and analyzing a part of the molten metal, it is possible to grasp the components of the entire molten metal, and if the components are not aimed, the components can be adjusted by additionally charging the necessary raw materials. It is also possible to plan.

However, in the case of melting by the cold crucible induction melting method, on the construction of the device, especially on the power supply equipment for flowing the required amount of high-frequency current to the coil arranged on the outer periphery of the crucible, a device with an originally large capacity crucible is constructed. If you try to build and operate a device with a large-capacity crucible that is difficult to do, it will entail a huge economic burden, and as a result, construct and operate a device with a correspondingly small-capacity crucible. As a result, there is a problem that the ingot obtained by the effort is correspondingly small. In small ingots, yields and productivity declines when processed into products. Therefore, a large ingot (at least 1 ton or more) is required for wrought material applications.

 On the other hand, the conventional method for producing an ingot by remelting a consumable electrode made of a metal raw material by a vacuum arc remelting method can produce a large ingot of about several tons. However, the consumable electrode used in the vacuum arc remelting method is manufactured by laminating metal raw materials in the axial direction, so that the axial component becomes inhomogeneous, and such a consumable electrode is used. The manufactured ingot also has a problem that the axial component becomes inhomogeneous.

 Patent Document 1: Japanese Patent Laid-Open No. 2001-131651

 Patent Document 2: JP-A-9-31558

 Disclosure of the invention

 Problems to be solved by the invention

[0004] The problem to be solved by the present invention is an ingot capable of economically obtaining a large and homogeneous ingot even when it contains a high melting point active metal such as Ti. The manufacturing method is provided.

 Means for solving the problem

 [0005] The present invention for solving the above-mentioned problems is that an ingot is formed from a molten metal melted by a cold crucible induction melting method, a consumable electrode is formed using the ingot, and then the consumable electrode is remelted by a vacuum arc. The present invention relates to a method for producing an ingot characterized by remelting by a method and forging a large ingot from the molten metal. According to this method, the components of the ingot produced by the cold crushed induction melting method can be adjusted within the target range, and the entire ingot can be made a homogeneous component. The ingredients are also homogeneous. Therefore, if the consumable electrode is remelted by the vacuum arc remelting method, a large and uniform ingot can be manufactured.

 [0006] In the present invention, known methods can be applied to the cold crucible induction melting method and the vacuum arc remelting method per se, but the production method of the present invention includes the following A step, B step and C step. The process through is advantageous.

Process A: Metal raw material is melted by cold crucible induction melting method, and the molten metal is small. The process of forging a small ingot by inserting into a mold mold.

 Step B: A step of bundling a plurality of forged small ingots after repeating the same operation as step A once or twice or more.

 Process C: Process that uses the material bundled in Process B as a consumable electrode, remelts it by vacuum arc remelting method, and inserts the molten metal into a large mold to produce a large ingot.

[0007] In addition, as the production method of the present invention, a method through the following a step, b step and c step is advantageous.

 Step a: A process in which a metal raw material is melted by a cold crucible induction melting method, and the molten metal is poured into a part of a large saddle to make a small ingot corresponding to the part.

 Step b: A step in which the same operation as step a is repeated one or more times, and the ingot is added in a large bowl.

 Process c: A process in which the material added in process b is used as a consumable electrode, remelted by a vacuum arc remelting method, and the molten metal is poured into a large mold to produce a large ingot.

[0008] First, the method through the A step, the B step and the C step (hereinafter referred to as the former method) will be described in further detail. In step A of the former method, a metal raw material is melted by a cold crucible induction melting method, and the molten metal is poured into a small bowl to produce a small ingot. Here, the small ingot is a relative meaning of a small ingot compared to the large ingot obtained in the process C, and its mass is not particularly limited. This means an ingot of the order. When melting a metal raw material by the cold crushed induction melting method, it is advantageous to have a processing capacity such that an ingot of about several hundred kg to 10 kg is obtained in terms of construction of the apparatus to be used, operation thereof, and economy. Because.

[0009] In Step B of the former method, the same operation as Step A is further repeated once or twice or more, and then a plurality of forged small ingots are bundled. The shape of each small ingot is not particularly limited as long as it can be used as a consumable electrode for vacuum arc remelting by bundling them in B process and bundling in C process! Also, the means of bundling is not particularly limited, but usually multiple small ingots are welded at their joints, and vacuum arc remelting in the C process. The shape of the consumable electrode used in the method. Then, in the C process of the former method, the one bundled in the B process is used as a consumable electrode and remelted by a vacuum arc remelting method, and the molten metal is poured into a large saddle mold to produce a large ingot. . Here, the large ingot is a large ingot compared to the small ingot obtained in the process A, and its mass is not particularly limited. It means a degree of ingot.

 [0010] Next, a method through steps a, b, and c (hereinafter referred to as the latter method) will be described in more detail. In step a of the latter method, a metal raw material is melted by a cold crucible induction melting method, and the molten metal is poured into a part of a large bowl to produce a small ingot corresponding to the part. Here, “large” or “small” is a relative meaning as described above.

 [0011] In step b of the latter method, the same operation as step a is further repeated once or twice or more, and the ingot is added in a large bowl. The shape of each ingot to be added in a large saddle is not particularly limited as long as it can be used as a consumable electrode in the vacuum arc remelting method by adding them in step c. The means for adding is not particularly limited, and can be sequentially laminated, or these can be removed sequentially using a dummy formwork, partition plate, etc. A small ingot that solidifies first is integrated with a small ingot that solidifies first. In step c of the latter method, the material added in step b is used as a consumable electrode, remelted by the vacuum arc remelting method, and the molten metal is poured into a large vertical mold to produce a large ingot. . Here, “large” is a relative meaning as described above.

[0012] In the present invention, in the B process, the former method of bundling a plurality of small ingots so as to be joined along the surface along the axial direction of the consumable electrode used in the C process, or in the b process, the ingot The latter method, in which the consumable electrodes used in step c are successively added on the surface along the axial direction, is advantageous. According to these methods, since the components in the axial direction of the ingot produced in step A or step a are uniform, they are bundled so as to be joined on the surface along the axial direction of the consumable electrode, or sequentially added. As a result, a consumable electrode having a uniform component in the axial direction can be manufactured, so that a large ingot having a uniform component as a whole can be easily manufactured. Ma Furthermore, according to these methods, even if the components of each ingot produced in the process A or the process a are slightly different, they are bundled in the process B, or the consumable electrodes manufactured by sequentially adding them in the process b are redissolved. As long as the molten metal of each ingot is mixed, the component may be within the range of the target component of the large ingot. Therefore, for example, if an element of the first ingot produced exceeds the target range, the adjustment of the element will be adjusted if the element of the next ingot to be produced is less than the target range. It is possible.

 [0013] Further, in the present invention, in the B process, the former method of bundling a plurality of small ingots so as to be joined on the surface along the radial direction of the consumable electrode used in the C process, and in the b process, the ingot is The latter method, in which the consumable electrodes used in the process c are sequentially stacked in the axial direction, is also advantageous. According to these methods, a large ingot having a uniform axial component can be produced without using a specially shaped saddle. When manufacturing a large ingot by these methods, in order to make the components in the axial direction uniform, only the sample in which the molten metal is sampled and analyzed in step A or step a and several small ingot components are uniformly adjusted is used. Force required to be used in step B or b The cold crucible induction dissolution method has the advantage that the components can be grasped and adjusted, so this method can be applied.

 [0014] In both the former method and the latter method described above, the type and composition of the metal raw material used in step A or step a is not particularly limited, but it can be high as Ti, Nb, W, Zr or Ta. When the active metal having a melting point or an alloy thereof is highly effective, the effect is higher when it is Ti or Ti alloy. In addition, when melting the metal raw material in step A or step a of both methods, a part of the molten metal is sampled and analyzed, and the molten metal composition being melted is readjusted based on the result. Is preferred.

 The invention's effect

 [0015] According to the present invention, there is an effect that a large and homogeneous ingot can be obtained economically even when it contains a high melting point active metal such as Ti. Brief Description of Drawings

 FIG. 1 is a perspective view illustrating a joining form of consumable electrodes used in the present invention.

FIG. 2 is a perspective view illustrating another joining form of consumable electrodes used in the present invention. FIG. 3 is a perspective view illustrating still another joining form of the consumable electrode used in the present invention.

 FIG. 4 is a perspective view illustrating the state of the first swaging operation in the present invention.

 FIG. 5 is a cross-sectional view illustrating the same state as FIG.

 FIG. 6 is a cross-sectional view illustrating the state of the next swaging operation of FIG. 5 in the present invention.

 FIG. 7 is a cross-sectional view illustrating the state of the next swaging operation of FIG. 6 in the present invention.

 8 is a cross-sectional view illustrating the state of the next swaging operation of FIG. 7 in the present invention.

 FIG. 9 is a cross-sectional view illustrating the state of the next swaging operation of FIG. 8 in the present invention.

 FIG. 10 is a cross-sectional view illustrating the state of the next swaging operation of FIG. 9 in the present invention.

 FIG. 11 is a cross-sectional view illustrating the state of the next swaging operation of FIG. 10 in the present invention.

 FIG. 12 is a cross-sectional view illustrating the state of the next swaging operation of FIG. 11 in the present invention.

 FIG. 13 is a cross-sectional view illustrating the state of the next swaging operation of FIG. 12 in the present invention.

 Explanation of symbols

 [0017] la ~ ld, 2a ~ 2d, 3a ~ 3d, 5a ~ 5d Small ingot

 1-3 Consumable electrodes

 4 Vertical

 4a ~ 4d formwork

 Example

[0018] FIG. 1 is a perspective view illustrating a joining state of consumable electrodes used in the former method among the production methods of the present invention. A total of four small ingots la ~: Ld that are shaped like a cylinder cut by two surfaces orthogonal to each other along its axis. A single consumable electrode 1 is formed. FIG. 2 is a perspective view illustrating another joining form of the consumable electrode used in the former method of the manufacturing method of the present invention. A total of four small ingots 2a to 2d, which are shaped like a cylinder cut by three planes parallel to the axial direction, are bundled together by welding in a state of being joined by planes along the axial direction. A single consumable electrode 2 is formed. FIG. 3 is a perspective view illustrating still another bonding form of the consumable electrode used in the former method of the manufacturing method of the present invention. It is shaped like a cylinder cut by three planes parallel to the radial direction.A total of four small ingots 3a to 3d are melted in a state where they are joined on the plane along the radial direction. They are bundled by contact to form one consumable electrode 3.

 [0019] FIGS. 4 to 13 are diagrams illustrating the steps of the a process and the b process in the latter method of the manufacturing method of the present invention (FIG. 4 is a perspective view, and FIGS. 5 to 13 are cross-sectional views). ). 4 and 5, dummy molds 4a to 4d having the same shape are slidably fitted to each other in a large saddle 4 having a cylindrical space. First, in FIGS. 6 and 7, the mold 4a is removed, and the molten metal melted by the cold crucible induction melting method is poured into the space corresponding to the mold 4a formed there to produce a small ingot 5a. Next, in FIGS. 8 and 9, the mold 4b is removed, and a small ingot 5b is manufactured by pouring molten metal melted by the cold-cable induction melting method into the space corresponding to the mold 4b formed there. Add to ingot 5a and unite. Further, in FIGS. 10 and 11, the mold 4c is removed, and a small ingot 5c is manufactured simultaneously with the molten metal melted by the cold crucible induction melting method into the space corresponding to the mold 4c formed there. , Add to 5b and integrate. 12 and 13, the mold 4d is removed, and the molten metal melted by the cold crucible induction melting method is poured into the space corresponding to the mold 4d formed there, and at the same time, a small ingot 5d is manufactured and the ingot 5a, Add to 5b and 5c and integrate. The one that has been made into a single piece is used as a consumable electrode in the vacuum arc remelting method in step c. As described above, the latter method can be performed by sequentially laminating the molten metal in the vertical mold in addition to the method using the dummy mold. As a method of sequentially laminating, the molten metal can be sequentially laminated in the vertical direction of the bowl shape, or the molten metal can be sequentially laminated with the upper force in a state where the bowl shape is laid down.

 [0020] Example 1

 The a process and the b process were performed under the following conditions, with the same force as that shown in FIGS.

 Metal raw material: Ti alloy (6 A1— 4 V— Ti)

 Cold Crucible Induction Melting: Input power 3000kW, frequency 2500Hz, crucible inner diameter 700mm, single melting 450kg, mass of each ingot 5a-5d 400kg

Next, the c process was performed under the following conditions using the large ingot 5 added through the a process and the b process as a consumable electrode. Vacuum arc remelting: current 15kA, voltage 35V, vacuum lPa, crucible inner diameter Z consumable electrode outer diameter ratio 1ZO. 85, mass of large forged ingot 1.6t

Chikarabe to the large ingot was prepared, its top, and analyzed the content of A1 and V but was out cutting the intermediate portion and bottom (mass _^0/0). The analysis was performed 5 times, and the average value is shown in Table 1.

[0021] Comparative Example 1

 Same as Example 1 Press-formed metal raw material for Ti alloy was used as a consumable electrode, and the primary vacuum arc melting was performed under the same conditions as in Example 1, and the same size as in Example 1 was obtained from the molten metal. A consumable electrode for redissolution was prepared. Example using this consumable electrode for remelting

Secondary vacuum arc melting (vacuum arc remelting) was performed under the same conditions as in 1. An ingot having the same size as that of Example 1 was produced from the molten metal. This ingot was analyzed in the same manner as in Example 1, and the average value is shown in Table 1.

[0022] [Table 1]

[0023] As is clear from Example 1, Comparative Example 1 and Table 1 showing these results, according to the present invention, this is the case where a high melting point active metal such as Ti is contained. However, a large and homogeneous ingot can be obtained economically. Table 1 shows the results of the manufacturing method according to the present invention when the latter method is used. However, almost the same results are obtained when the former method is omitted. ing.

Claims

The scope of the claims  [1] An ingot is made from the molten metal melted by the cold crucible induction melting method, a consumable electrode is formed using this ingot, and then the consumable electrode is remelted by the vacuum arc remelting method. A method for producing an ingot characterized by forging an ingot.  [2] The method for producing an ingot according to claim 1, which undergoes the following step A, step B and step C.  Process A: A process in which a metal raw material is melted by a cold crucible induction melting method, and the molten metal is poured into a small mold to make a small ingot.  Step B: A step of bundling a plurality of forged small ingots after repeating the same operation as step A once or twice or more.  Process C: Process that uses the material bundled in Process B as a consumable electrode, remelts it by vacuum arc remelting method, and inserts the molten metal into a large mold to produce a large ingot. [3] The method for producing an ingot according to claim 1, wherein the method undergoes the following steps a, b and c.  Step a: A process in which a metal raw material is melted by a cold crucible induction melting method, and the molten metal is poured into a part of a large saddle to make a small ingot corresponding to the part.  Step b: A step in which the same operation as step a is repeated one or more times, and the ingot is added in a large bowl.  Process c: A process in which the material added in process b is used as a consumable electrode, remelted by a vacuum arc remelting method, and the molten metal is poured into a large mold to produce a large ingot. [4] The method for producing an ingot according to claim 2, wherein in the step B, a plurality of small ingots are bundled so as to be joined on a surface along the axial direction of the consumable electrode used in the step C. [5] The method for producing an ingot according to claim 3, wherein the ingot is successively added on the surface along the axial direction of the consumable electrode used in the step c after the step b. [6] The method of manufacturing an ingot according to claim 2, wherein in the step B, a plurality of small ingots are bundled so as to be joined on a surface along the radial direction of the consumable electrode used in the step C. [7] The method for producing an ingot according to claim 3, wherein the ingot is successively added on a surface along a radial direction of the consumable electrode used in the step c after the step b. The method for producing an ingot according to any one of claims 1 to 7, wherein the metal raw material is an active metal having a high melting point or an alloy thereof.  The method for producing an ingot according to any one of claims 1 to 7, wherein the metal raw material is Ti or a Ti alloy.