WO2018061540A1 - HOT EXTRUSION-MOLDING METHOD FOR Ni-BASED SUPER HEAT-RESISTANT ALLOY AND PRODUCTION METHOD FOR Ni-BASED SUPER HEAT-RESISTANT ALLOY EXTRUSION MATERIAL - Google Patents

Abstract

Provided are: a hot extrusion-molding method for a precipitation strengthened-type Ni-based super heat-resistant alloy; and a production method for a Ni-based super heat-resistant alloy extrusion material. The hot extrusion-molding method is for a Ni-based super heat-resistant alloy, wherein: a billet has a component composition for a precipitation strengthened-type Ni-based super heat-resistant alloy which has a gamma prime phase equilibrium precipitation amount of 40 mol% or more at 700°C; a lubrication glass pad is installed between a die and the billet; and an adjustment is made such that the relationship between the outer diameter D_B (mm) of the billet at the time of being inserted in a container and the inner diameter D_C (mm) of the container satisfies the condition, (D_C-D_B): 2-8 mm, or an adjustment is made such that the relationship between the outer diameter D_B' (mm) of the billet prior to being heated to a hot processing temperature and the inner diameter D_C' (mm) of the container prior to being heated to a preheating temperature satisfies the condition, (D_C'-D_B'): 3-9 mm. The production method for a Ni-based super heat-resistant alloy extrusion material is performed using the hot extrusion-molding method mentioned above.

Description

Method for hot extrusion molding of Ni-base superalloy and method for producing extruded Ni-base superalloy

The present invention relates to a hot extrusion molding method of a precipitation strengthening type Ni-base superalloy and a method of manufacturing a Ni-base superalloy extruded material.

In extrusion molding, the billet is heated to a hot working temperature, the billet heated to the hot working temperature is inserted into a container, a compressive force is applied to the billet inserted into the container, and a die installed in the container is placed. This is hot extrusion molding in which a billet is extruded from a hole. FIG. 2 is a schematic diagram illustrating an example of a cross-sectional structure of the extrusion molding apparatus. In FIG. 2, first, the billet 1 heated to the hot working temperature is inserted into the container 2. Next, a compressive force is applied to the billet 1 inserted into the container 2 by the stem 4 via the dummy block 3. Thus, the billet 1 is extruded from the hole of the die 5 installed in the container 2 and formed into an extruded material 6 having a hole-shaped cross section of the die 5.

Among various extrusion molding methods, “Direct Extrusion” is a press machine that applies a compressive force to the billet from one end of the container into which the billet is inserted, and extrudes the billet from the hole of the die installed on the other end of the container. This is the simplest and most basic extrusion method. In the case of direct extrusion, lubrication between the billet and the container is important. Therefore, conventionally, when inserting a billet heated to a hot working temperature into a container, a “lubricant-enclosed direct extrusion” is proposed in which a glass lubricant is applied to the peripheral surface of the billet and then inserted (patent document). 1). For the purpose of improving the lubricity between the billet and the die, “glass lubrication extrusion” in which a lubricating glass pad is mounted between the billet and the die has been proposed (Patent Document 2).

JP-A-6-269844 Japanese Patent Laid-Open No. 7-136710

In recent years, a wire of “Ni-based super heat-resistant alloy” has been demanded in response to repairs of various heat-resistant parts and three-dimensional modeling. Among the Ni-base superalloys, the “precipitation strengthened” Ni-base superalloys are excellent in high-temperature strength. However, the Ni-base superalloys having this special component composition are poor in hot workability, Wire formation by molding was very difficult.
An object of the present invention is to provide a method for hot extrusion of a precipitation-strengthened Ni-base superalloy and a method for producing a Ni-base superalloy extruded material.

The present invention heats a billet to a hot working temperature, inserts the billet heated to the hot working temperature into a container, applies a compressive force to the billet inserted into the container, and inserts a hole in a die installed in the container. In a hot extrusion molding method in which a billet is extruded and molded from
The hot extrusion molding method is based on direct extrusion in which a compressive force is applied to the billet from one end side of the container into which the billet is inserted, and the billet is extruded from a hole of a die installed on the other end side of the container.
The above hot extrusion molding method is based on glass lubrication extrusion in which a glass pad for lubrication is mounted between a die and a billet.
The billet has a component composition of a precipitation-strengthened Ni-base superalloy having an equilibrium precipitation amount of gamma prime at 700 ° C. of 40 mol% or more,
Adjust so that the relationship between the outer diameter D _B (mm) of the billet when inserted into the container and the inner diameter D _C (mm) of the container is (D _C -D _B ): 2 to 8 mm, or The relationship between the outer diameter D _B ′ (mm) of the billet before heating to the hot working temperature and the inner diameter D _C ′ (mm) of the container before heating to the preheating temperature is (D _C ′ −D _B '): This is a hot extrusion molding method of a Ni-base superalloy that is adjusted to 3 to 9 mm.

At this time, the inner diameter D _C (mm) of the container is preferably 60 to 180 mm, or the inner diameter D _C ′ (mm) of the container is preferably 60 to 180 mm. The hot working temperature is preferably 1150 to 1180 ° C.

The present invention also includes a first step of heating the billet of the Ni-base superalloy to a hot working temperature;
A billet heated to the above hot working temperature is inserted into a container, a compressive force is applied to the billet from one end side of the container, the billet is extruded from a hole of a die installed on the other end side of the container, and Ni base A second step of obtaining a super heat-resistant alloy extruded material,
The billet of the Ni-base superalloy described above has a component composition of a precipitation-strengthened Ni-base superalloy having an equilibrium precipitation amount of gamma prime at 700 ° C. of 40 mol% or more,
The relationship between the outer diameter D _B (mm) of the billet when inserted into the container and the inner diameter D _C (mm) of the container when the lubricating glass pad is mounted between the die and the billet, (D _C -D _B ): Adjust to 2 to 8 mm, or before billet outer diameter D _B ′ (mm) before heating to the above hot working temperature and preheating temperature Ni base super heat-resistant alloy extruded material which is subjected to the second step by adjusting so that the relationship with the inner diameter D _C ′ (mm) of the container is (D _C ′ −D _B ′): 3 to 9 mm It is a manufacturing method.

At this time, it is preferable to adjust the inner diameter D _C (mm) of the container to 60 to 180 mm, or to adjust the inner diameter D _C ′ (mm) of the container to 60 to 180 mm. The hot working temperature is preferably 1150 to 1180 ° C.

According to the present invention, hot extrusion of a precipitation strengthening type Ni-base superalloy is possible.

In direct extrusion by glass lubrication, the difference “D _C -D _B (mm)” between the outer diameter D _B (mm) of the billet and the inner diameter D _C (mm) of the billet when inserted into the container, It is a graph which shows an example of the result of having calculated | required the relationship with the "thickness (mm) of a lubricating film" formed between the billet and a container by simulation. It is the schematic of the cross-section of an extrusion molding apparatus which shows an example of the apparatus which performs direct extrusion molding by glass lubrication. It is the drawing substitute photograph which showed an example of the surface state of the extrusion material produced with the method of the example of this invention. It is the drawing substitute photograph which showed an example of the surface state of the extrusion material produced with the method of the comparative example.

(1) The hot extrusion molding method of the present invention applies a compressive force to the billet from one end side of the container into which the billet is inserted, and extrudes the billet from the hole of the die installed on the other end side of the container. Is due to. The hot extrusion molding method of the present invention is based on “glass lubrication extrusion” in which a lubricating glass pad is mounted between a die and a billet.
FIG. 2 is a cross-sectional structure of an extrusion molding apparatus showing an example of an apparatus for performing direct extrusion molding by glass lubrication. In FIG. 2, the billet 1 inserted into the container 2 is pushed out from a hole of a die 5 provided on the other end side of the container 2 with a compressive force applied from one end side of the container 2. In the case of glass lubrication extrusion, a lubricating glass pad 7 is mounted between the die 5 and the billet 1 when the billet 1 is inserted into the container 2. At this time, when the die 5 is installed in the container 2 via the die holder, the die 5 in FIG. 2 includes a die holder (not shown). Strictly speaking, when the cross-sectional structure of the extrusion molding apparatus is in the state shown in FIG. 2 (that is, when the billet 1 is extruded to some extent from the hole of the die 5), the lubricating glass pad 7 has already been provided. It is melted. In the case of the present invention, the molten lubricating glass pad 7 is sufficiently infiltrated between the billet 1 and the container 2. The molten glass pad 7 for lubrication is firmly adhered to the surface of the extruded material 6 extruded from the hole of the die 5.
In the present invention, generally known materials can be used as the lubricating glass pad 7. For example, the lubricating glass pad 7 is formed by solidifying various glass materials with a binder. For example, the shape has a “disk shape” that fits between the die 5 and the billet 1 (hence, also called a glass disk). For example, a “hole” corresponding to the position and diameter of the hole of the die 5 is opened at the center of the disk shape. A plurality of such glass pads for lubrication 7 can be used in piles depending on the case. Since the billet is made of a precipitation-strengthened Ni-base superalloy, for the present invention in which the extrusion is performed at a high temperature, such a lubricating glass pad can be quickly melted and the molten lubricating pad It is effective in increasing the flow rate of the glass pad (ie, improving the lubricity between the billet and the container).
The billet may be an ingot obtained by casting a molten metal, or a material obtained by subjecting the ingot to a lump processing, machining, heat treatment, or the like, if necessary. Moreover, as said ingot, the sintering raw material obtained by the powder metallurgy method can also be used.

(2) In the hot extrusion molding method of the present invention, the billet has a component composition of a precipitation-strengthened Ni-base superalloy having an equilibrium precipitation amount of gamma prime at 700 ° C. of 40 mol% or more. is there.
Precipitation-strengthened Ni-base superalloys have a microstructure that consists exclusively of a gamma phase in which alloy components are dissolved in a Ni base and precipitation strengthening of intermetallic compounds typically represented by [Ni ₃ (TiAl)]. It is composed of a gamma prime phase that is a phase. The hot working of such a Ni-base superalloy is generally performed from the solid solution temperature (gamma prime solvus temperature) at which the above-mentioned gamma prime phase is in solution to the solidus temperature of this Ni-base superalloy. In the temperature range (for example, 900 ° C. to 1200 ° C.). At the time of hot working, if the gamma prime phase is large, the deformation resistance becomes high and the hot workability of the entire Ni-base superalloy is lowered. And if this hot working is also hot extrusion molding with a high working ratio, for example, the extruded material after molding is divided, and thus hot working of precipitation-strengthened Ni-base superalloy is difficult. there were.

Normally, the gamma prime phase in a Ni-base superalloy is reduced as the temperature of the alloy itself (that is, hot working temperature) increases. It is possible that the hot workability of the heat resistant alloy can be improved somewhat. However, even when the hot working temperature is increased, the above-mentioned alloy having many gamma prime phases, specifically, a Ni-based superalloy having a component composition in which the equilibrium precipitation amount of gamma prime at 700 ° C. is 40 mol% or more. Is a Ni-based superalloy that is particularly difficult to hot work because the gamma prime phase does not disappear even when it is heated to a temperature near the melting point. In the hot extrusion molding method of the present invention, such a Ni-base superalloy that is difficult to hot work is used as a billet, and this is “extruded”.
The hot extrusion molding method of the present invention enables extrusion of a Ni-base superalloy having a large amount of gamma prime and is difficult to hot-work. Is expensive. From this point of view, the billet extruded in the present invention has an equilibrium precipitation amount of gamma prime at 700 ° C. of preferably 50 mol% or more. More preferably, it is 60 mol% or more. It is not particularly necessary to set an upper limit for this value. However, about 75 mol% is realistic.

The equilibrium precipitation amount of gamma prime of the precipitation strengthened Ni-base superalloy is the amount of precipitation of gamma prime that is stable in a thermodynamic equilibrium state. And the value which expressed the equilibrium precipitation amount of this gamma prime in "mol%" is a value which can be decided by the component composition which precipitation strengthening type Ni-base superalloy has. The value of “mol%” of the equilibrium precipitation amount can be obtained by analysis by thermodynamic equilibrium calculation. In the case of analysis by thermodynamic equilibrium calculation, it can be obtained accurately and easily by using various thermodynamic equilibrium calculation software.
As the precipitation strengthening type Ni-based superalloy having an equilibrium precipitation amount of gamma prime at 700 ° C. of “40 mol% or more”, for example, in mass%, C: 0.001 to 0.25%, Cr : 8.0-22.0%, Mo: 2.0-7.0%, Al: 2.0-8.0%, Ti: 0.4-7.0%, balance Ni and impurities (Hereinafter, “mass%” is simply referred to as “%”). In the above basic component composition, if necessary, Co: 28.0% or less, W: 6.0% or less, Nb: 4.0% or less, Ta: 3.0% or less, Fe: 10.0% or less, V: 1.2% or less, Hf: 1.0% or less, B: 0.300% or less, Zr: 0.30% or less The above elemental species can be contained. Typical examples of such Ni-base superalloys include Alloy 713C and UDIMET 720 (UDIMET is a registered trademark of Special Metals Corporation).

With respect to the above-described component composition, the effects of the individual elements will be described.
<C: 0.001 to 0.25%>
C has an effect of increasing the strength of the grain boundary of the Ni-base superalloy. Moreover, there exists an effect which improves the castability of Ni-base superalloy. However, when the C content increases, coarse eutectic carbide precipitates in the final solidified portion of the ingot during casting. And this coarse carbide | carbonized_material increases, and the hot workability at the time of extrusion molding is reduced. Therefore, the C content is preferably 0.001 to 0.25%. More preferably, it is 0.10% or less, More preferably, it is 0.05% or less. Particularly preferably, the content is 0.02% or less. Further, it is more preferably 0.003% or more, further preferably 0.005% or more. Particularly preferably, it is 0.008% or more.

<Cr: 8.0 to 22.0%>
Cr is an element that improves oxidation resistance and corrosion resistance. However, when Cr is excessively contained, an embrittlement phase such as a σ phase is formed, and the strength and hot workability are lowered. Therefore, the Cr content is preferably 8.0 to 22.0%. More preferably, it is 9.0% or more, More preferably, it is 9.5% or more. Particularly preferably, it is 10.0% or more. Further, it is more preferably 18.0% or less, and further preferably 16.0% or less. Particularly preferably, it is 14.0% or less.

<Mo: 2.0 to 7.0%>
Mo contributes to the solid solution strengthening of the matrix and has the effect of improving the high temperature strength. However, when Mo is excessive, an intermetallic compound phase is formed and high temperature strength is impaired. Therefore, the Mo content is preferably 2.0 to 7.0%. More preferably, it is 2.5% or more, More preferably, it is 3.0% or more. Particularly preferably, it is 3.5% or more. Further, it is more preferably 6.0% or less, and still more preferably 5.5% or less. Particularly preferably, it is 5.0% or less.

<Al: 2.0 to 8.0%>
Al is an element that improves the high-temperature strength by forming gamma prime. However, excessive inclusion of Al reduces hot workability and causes material defects such as cracks during extrusion molding. Therefore, the content of Al is preferably set to 2.0 to 8.0%. More preferably, it is 2.5% or more, More preferably, it is 3.5% or more. Particularly preferably, it is 4.5% or more. Further, it is more preferably 7.5% or less, and still more preferably 7.0% or less. Particularly preferably, it is 6.5% or less.

<Ti: 0.4-7.0%>
Ti, like Al, is an element that forms a gamma prime and enhances the high temperature strength by solid solution strengthening of the gamma prime. However, when Ti is contained excessively, a harmful η (eta) phase is formed, and hot workability is impaired. Therefore, the Ti content is preferably 0.4 to 7.0%. More preferably, it is 0.45% or more, More preferably, it is 0.5% or more. Further, it is more preferably 5.0% or less, and further preferably 3.0% or less. Especially preferably, it is 1.0% or less.

The remainder other than the elements described above is Ni, but naturally unavoidable impurities may be included. And in this basic component composition, the following element seed | species can be contained further as needed.

<Co: 28.0% or less>
Co is one of the selective elements that improves the stability of the structure and makes it possible to maintain hot workability even when containing a large amount of Ti as a strengthening element. On the other hand, since Co is expensive, the cost increases. Therefore, even when Co is contained, the Co content is preferably 28.0% or less. More preferably, it is 18.0% or less, More preferably, it is 16.0% or less. Particularly preferably, it is 13.0% or less. And when it is good also considering Co as an additive-free level (inevitable impurity level of a raw material), the minimum of Co shall be 0%. And Co can be made into less than 1.0%.
In addition, when acquiring said effect by content of Co, it is preferable that content of Co shall be 1.0% or more. More preferably, it is 3.0% or more, More preferably, it is 8.0% or more. Particularly preferably, it is 10.0% or more.

<W: 6.0% or less>
W, like Mo, is one of the selective elements that contribute to the solid solution strengthening of the matrix. On the other hand, when W is excessive, a harmful intermetallic compound phase is formed, and the high-temperature strength deteriorates. Therefore, even if it contains W, the W content is preferably 6.0% or less. More preferably, it is 5.5% or less, More preferably, it is 5.0% or less. Particularly preferably, it is 4.5% or less. And when W is good also as an additive-free level (inevitable impurity level of a raw material), the minimum of W shall be 0%. And W can be made into less than 1.0%, and also can be made into less than 0.8%.
In addition, when acquiring said effect by content of W, it is preferable that content of W shall be 1.0% or more. And by containing W and Mo in a composite, it is effective for exhibiting the above-mentioned solid solution strengthening. The content of W in a case where it is combined with Mo is preferably 0.8% or more.

<Nb: 4.0% or less>
Nb, like Al and Ti, is a selective element that forms a gamma prime and enhances the high-temperature strength by solid-solution strengthening the gamma prime. However, an excessive content of Nb forms a harmful δ (delta) phase and degrades hot workability. Therefore, even when Nb is contained, the Nb content is preferably 4.0% or less. More preferably, it is 3.5% or less, More preferably, it is 3.0% or less. Particularly preferably, it is 2.5% or less. And when it is good also considering Nb as an additive-free level (inevitable impurity level of a raw material), the minimum of Nb shall be 0%. And Nb can be made into less than 0.5%.
In addition, when acquiring said effect by content of Nb, it is preferable that content of Nb shall be 0.5% or more. More preferably, it is 1.0% or more, More preferably, it is 1.5% or more. Particularly preferably, it is 2.0% or more.

<Ta: 3.0% or less>
Ta, like Al and Ti, is one of the selective elements that form gamma prime and enhance the high temperature strength by solid solution strengthening of gamma prime. However, excessive addition of Ta causes the gamma prime phase to become unstable at a high temperature and cause coarsening at a high temperature, and forms a harmful η (eta) phase, thereby degrading hot workability. Therefore, even if it contains Ta, the content of Ta is preferably 3.0% or less. More preferably, it is 2.5% or less, More preferably, it is 2.0% or less. Particularly preferably, it is 1.5% or less. And when it is good also considering Ta as an additive-free level (inevitable impurity level of a raw material), the minimum of Ta is made into 0%. And Ta can be made into less than 0.3%.
In addition, when acquiring said effect by content of Ta, it is preferable that content of Ta shall be 0.3% or more. More preferably, it is 0.5% or more, More preferably, it is 0.7% or more. Particularly preferably, it is 1.0% or more.

<Fe: 10.0% or less>
Fe is one of the selective elements that can be contained as an alternative to expensive Ni and Co and is effective in reducing alloy costs. However, when Fe is contained excessively, an embrittlement phase such as a σ phase is formed, and the strength and hot workability are lowered. Therefore, even if it contains Fe, the content of Fe is preferably 10.0% or less. More preferably, it is 8.0% or less, More preferably, it is 6.0% or less. Particularly preferably, it is 3.0% or less. And when it is good also considering Fe as an additive-free level (inevitable impurity level of a raw material), the minimum of Fe shall be 0%. And Fe can be made into less than 0.1%.
In addition, when acquiring said effect by content of Fe, it is preferable that content of Fe substituted with content of Ni or Co shall be 0.1% or more, for example. More preferably, it is 0.4% or more, More preferably, it is 0.6% or more. Especially preferably, it is 0.8% or more.

<V: 1.2% or less>
V is one of the selective elements useful for strengthening the solid solution of the matrix and strengthening the grain boundaries by forming carbides. However, excessive addition of V leads to the formation of a high temperature unstable phase in the production process, which adversely affects manufacturability and high temperature mechanical performance. Therefore, even if it contains V, the V content is preferably 1.2% or less. More preferably, it is 1.0% or less, More preferably, it is 0.8% or less. Particularly preferably, it is 0.7% or less. And when it is good also considering V as an additive-free level (inevitable impurity level of a raw material), the minimum of V is made into 0%. And V can be made into less than 0.1%.
In addition, when acquiring said effect by content of V, it is preferable that content of V shall be 0.1% or more. More preferably, it is 0.2% or more, More preferably, it is 0.3% or more. Particularly preferably, it is 0.5% or more.

<Hf: 1.0% or less>
Hf is one of the selective elements useful for improving the oxidation resistance of alloys and strengthening grain boundaries by forming carbides. However, excessive addition of Hf leads to the production of oxides and high temperature unstable phases in the production process, which adversely affects manufacturability and high temperature dynamic performance. Therefore, even if it contains Hf, the content of Hf is preferably 1.0% or less. More preferably, it is 0.7% or less, More preferably, it is 0.5% or less. Particularly preferably, it is 0.3% or less. And when Hf is good also as an additive-free level (inevitable impurity level of a raw material), the minimum of Hf shall be 0%. And Hf can be less than 0.02%.
In addition, when acquiring said effect by content of Hf, it is preferable that content of Hf shall be 0.02% or more. More preferably, it is 0.05% or more, More preferably, it is 0.1% or more. Particularly preferably, it is 0.15% or more.

<B: 0.300% or less>
B is one of the selective elements that can improve the grain boundary strength and improve the creep strength and ductility. On the other hand, excessive addition of B lowers the melting point of the alloy and adversely affects high-temperature strength and hot workability. Therefore, even if it contains B, the B content is preferably 0.300% or less. More preferably, it is 0.100% or less, More preferably, it is 0.050% or less. Particularly preferably, it is 0.020% or less. And when B is good also as an additive-free level (inevitable impurity level of a raw material), the minimum of B shall be 0%. And B can be made into less than 0.001%.
In addition, when acquiring said effect by content of B, it is preferable that content of B shall be 0.001% or more. More preferably, it is 0.003% or more, More preferably, it is 0.005% or more. Particularly preferably, it is 0.007% or more.

<Zr: 0.30% or less>
Zr, like B, is one of the selective elements that has the effect of improving the grain boundary strength. However, if Zr is contained excessively, the melting point of the alloy is lowered, and the high-temperature strength and hot workability deteriorate. Therefore, even when Zr is contained, the Zr content is preferably set to 0.30% or less. More preferably, it is 0.25% or less, More preferably, it is 0.20% or less. Particularly preferably, it is 0.15% or less. And when it is good also considering Zr as an additive-free level (inevitable impurity level of a raw material), the minimum of Zr is made into 0%. And Zr can be made into less than 0.001%.
In addition, when acquiring said effect by content of Zr, it is preferable that content of Zr shall be 0.001% or more. More preferably, it is 0.005% or more, More preferably, it is 0.01% or more. Particularly preferably, it is 0.03% or more.

(3) In the hot extrusion molding method of the present invention, the relationship between the outer diameter D _B (mm) of the billet when inserted into the container and the inner diameter D _C (mm) of the container is (D _C -D _B ) : Adjust to 2 to 8 mm.
In hot extrusion molding of “precipitation strengthened Ni-base superalloys” having the above-mentioned special component composition, “outer diameter D _B (mm) of billet” when inserted into the container, and “container There is an optimal numerical relationship with the “inner diameter D _C (mm)”. In order to complete the above-described precipitation-strengthened Ni-base super heat-resistant alloy continuously and without extrusion interruption or breakage of the extruded material, it is necessary to use a “lubricating glass” mounted between a die and a billet. It is important to adjust the function of the pad. The lubricating glass pad is heated and melted when the billet heated to the hot working temperature is inserted into the container. And during extrusion molding, the molten glass pad improves the lubricity between the billet and the die. At this time, if the molten glass pad can be sufficiently infiltrated between the billet and the container, a "lubricating film" can be formed between the billet and the container, and the lubricity between the billet and the container can be formed. Can also be improved. However, the precipitation-strengthened Ni-base superalloy has poor “wetability” with respect to the molten glass pad as compared with general stainless steel and the like. Therefore, in the case of hot extrusion molding in which the billet is a precipitation-strengthened Ni-base superalloy, in order to sufficiently infiltrate the molten glass pad between the billet and the container, conditions for the extrusion molding, etc. Review is important. And in order to fully infiltrate the molten glass pad and to fully exert the effect of the infiltration of the molten glass pad, the billet and the container directly related to the ease of infiltration of the glass pad The present inventors have found that the optimization of the “clearance” between the two is effective.

FIG. 1 shows the difference between the outer diameter D _B (mm) of the billet and the inner diameter D _C (mm) of the billet in the hot extrusion molding of the billet made of the precipitation-strengthened Ni-base superalloy. An example of a result obtained by simulating the relationship between a certain “D _C -D _B (mm)” and the “thickness (mm) of the lubricating film” formed between the billet and the container being extruded. FIG. At this time, the part where the thickness of the lubricating film is obtained is the part where the thickness of the lubricating film is minimum in this billet. The result of FIG. 1 shows that the billet 1 is an elasto-plastic body, the container 2 and the dummy block 3 are rigid bodies, and the lubricating glass pad 7 is a rigid plastic body. It was obtained by calculation by analysis. At this time, since the operation in the extrusion direction is directly set in the dummy block 3, the stem 4 is not expressed in the analysis model. In the above calculation, the finite element analysis software “FORGE Nxt ver1.0” manufactured by TRANSVALOR was used, and the calculation was performed on the assumption that the lubricating glass pad 7 was completely melted by contact with the billet 1 in advance. .

From the result of FIG. 1, by reducing the clearance (that is, the value of “D _C -D _B (mm)”), a lubricating film having a sufficient thickness between the billet and the container during extrusion molding. It can be seen that can be formed. For example, it can be seen that by setting the above clearance to “8 mm or less”, a lubricating film having a thickness exceeding “0.05 mm” can be formed. This is considered to be caused by an increase in the flow rate of the molten glass pad. This can improve the lubricity between the billet and the container.
And if said clearance becomes large, the billet in extrusion molding will be easy to deform | transform into the radial direction of a billet toward the inner wall of a container. And at the site where the billet is greatly deformed in the radial direction, the gap between the billet and the container during extrusion is partially narrowed (closed), and the molten glass pad is blocked from flowing. The smooth flow of the glass pad is hindered. As a result, when a remarkable crack occurs on the surface of the billet, there is a concern that the extrusion molding cannot be completed because the extruded material after molding is divided.

However, it is not a good idea to make the above clearance too small. First, if the above clearance becomes too small, there is a concern that the smooth flow of the molten glass pad is hindered, such as the flow of the molten glass pad being blocked. As a result of this, for example, in the case of FIG. 1, the clearance tends to decrease and the thickness of the lubricating film tends to decrease after that when the clearance is “about 4 mm”. In FIG. 1, when the clearance is, for example, about “1 mm”, even if the thickness of the lubricating film is maintained at about “0.05 mm”, in fact, It is conceivable that the thickness is partially thin or broken.
In addition, if the clearance becomes too small, when the billet heated to the hot working temperature is inserted into the container in the pre-extrusion stage, the billet comes into contact with the inner wall of the container before the extrusion starts. In addition, there is a concern that the temperature of the billet will decrease considerably. In particular, in the case of precipitation strengthened Ni-base superalloys, the sensitivity to increase in deformation resistance against temperature drop is high compared to general stainless steel, etc. The deformation resistance of the billet is increased, which hinders the completion of extrusion molding.

Therefore, in the present invention, the relationship between the outer diameter D _B (mm) of the billet when inserted into the container and the inner diameter D _C (mm) of the container is “(D _C −D _B ): 2 to 8 mm”. Adjust as follows. In the range of 2 to 8 mm, for example, this can be further adjusted in the range of 2 to 4 mm, or can be adjusted in the range of 4 to 8 mm. The value of (D _C −D _B ) can be handled as an integer. For example, it can be a value obtained by rounding off decimals.
Moreover, generally the container of an extrusion molding apparatus is cylindrical, for example, is cylindrical. Accordingly, the billet has a columnar shape, for example, a columnar shape. In such a case, the value of (D _C −D _B ) can be adjusted at the parallel portion of the interval formed by the inner peripheral surface of the container and the outer peripheral surface of the billet.

The adjustment of the value of (D _C −D _B ) can be performed by adjusting the outer diameter of the billet, for example. And the adjustment of the outer diameter of this billet can be adjusted, for example, by the outer diameter of the billet before insertion into the container (that is, before heating to the hot working temperature). Adjustment of the outer diameter of the billet is based on the billet component composition and heating conditions by counting the thermal expansion amount of the billet when heated to the hot working temperature and the thermal expansion of the container when heated to the preheating temperature. Accordingly, it can be performed by machining such as turning. And, for example, the relationship between the outer diameter D _B ′ (mm) of the billet before heating to the hot working temperature and the inner diameter D _C ′ (mm) of the container before heating to the preheating temperature is (D _C '-D _B '): It can be adjusted to be 3 to 9 mm. In the range of 3 to 9 mm, for example, this can be further adjusted in the range of 3 to 5 mm, or can be adjusted in the range of 5 to 9 mm.
The value of (D _C ′ −D _B ′) can be adjusted at a parallel portion of the interval formed by the inner peripheral surface of the container and the outer peripheral surface of the billet.

At this time, if the inner diameter of the container becomes too large, it is necessary to produce a billet having a large outer diameter in order to maintain the above-described clearance according to the inner diameter of the container. By producing a billet with a large outer diameter, the handleability of the billet can be reduced considerably. And when the billet heated to the hot working temperature is inserted into the container, the billet temperature can be lowered if it takes time to handle the billet. Therefore, the inner diameter D _C (mm) of the container is preferably 180 mm or less. And it is more preferable to make this small, for example, 160 mm or less, 140 mm or less, 120 mm or less, and 100 mm or less.
Conversely, if the inner diameter of the container becomes too small, it is necessary to reduce the diameter of the billet. As the billet diameter decreases, the cooling rate of the heated billet itself increases. And, when the billet heated to the hot working temperature is inserted into the container, the temperature of the billet can be greatly reduced. Therefore, the inner diameter D _C (mm) of the container is preferably 60 mm or more. And it is more preferable to enlarge this to 70 mm or more and 80 mm or more, for example.

Then, the inner diameter D _C of the container instead of to a value above the inner diameter D _{C 'of} before the container is heated to a preheat temperature is preferably not greater than 180 mm. And it is more preferable to make this small, for example, 160 mm or less, 140 mm or less, 120 mm or less, and 100 mm or less. Further, it is preferably not less than 60mm inner diameter _{D C} 'of the container. And it is more preferable to enlarge this to 70 mm or more and 80 mm or more, for example.

In the case of the present invention, hot working when hot extruding a billet having “a component composition of a precipitation strengthening type Ni-base superalloy having an equilibrium precipitation amount of gamma prime of 40 mol% or more at 700 ° C.” The temperature is preferably “1150 to 1180 ° C.”. More preferably, it is 1170 degrees C or less. This extrusion molding at a high temperature contributes to maintaining the hot workability of the billet made of a precipitation-strengthened Ni-base superalloy. The extrusion molding at this high temperature promotes rapid melting of the above-described lubricating glass pad, and increases the flow rate of the molten lubricating glass pad, thereby improving the lubricity between the billet and the container. It is effective to improve.
In the case of the present invention, a glass lubricant may be applied to the peripheral surface of the billet when the billet heated to the hot working temperature is inserted into the container.

In the case of the present invention, it is conceivable that the diameter of the cross section of the produced extruded material is, for example, 10 to 130 mm. And the diameter of the cross section of this extrusion material may be 100 mm or less, may be 60 mm or less, and may be 30 mm or less. In the case of the present invention, the extrusion ratio (the cross-sectional area of the billet / the cross-sectional area of the extruded material) at the time of extrusion molding may be 70 or less, for example. And this extrusion ratio may be 40 or less, or 30 or less. Furthermore, it may be 20 or less, or 10 or less. Further, it may be 2 or more, 4 or more, or 6 or more.
The extruded material thus obtained has, for example, a bar shape or a wire shape. Further, these rods and wires have, for example, a solid state. Then, by using such an extruded material as a starting material, further hot working and cold working are performed on this, for example, to produce a thin wire having a cross-sectional diameter of 1 to 6 mm, further 4 mm or less, 3 mm or less, etc. It is also possible to do.

In the case of the present invention, the billet may be in a form in which a molded body (that is, a precipitation strengthened Ni-base superalloy) is contained in a container. Also in this case, the precipitation strengthening type Ni base is adjusted by adjusting to the value of (D _C -D _B ) described above or by adjusting to the value of (D _C '-D _B ') described above. Hot extrusion molding of super heat-resistant alloy is possible.

An ingot was obtained by casting a molten metal having a predetermined composition prepared by vacuum melting. The ingot was then machined to produce cylindrical billets A to E having a predetermined diameter and corresponding to Alloy 713C having a length of 105 mm. The diameters (D _B ′) of billets A to E were billet A: 83 mm, billet B: 82 mm, billet C: 80 mm, billet D: 76 mm, billet E: 72 mm.
Table 1 shows the component compositions of billets A to E (ie, ingots). Note that Co, W, Ta, V, and Hf are impurity elements, so Co ≦ 28.0%, W ≦ 6.0%, Ta ≦ 3.0%, V ≦ 1.2%, and Hf ≦ 1. It was 0%.
The amount of gamma-prime equilibrium precipitation of billets A to E at 700 ° C. was determined using thermodynamic equilibrium calculation software “JMatPro (Version 8.0.1, manufactured by Sente Software Ltd.)”. As a result of inputting the contents of each element listed in Table 1 into this thermodynamic equilibrium calculation software, the above-described equilibrium precipitation amount of billets A to E was “70 mol%”. The gamma prime solvus temperature of billets A to E was “1180 ° C.”.

Billets A to E were heated to the hot working temperature (first step). Then, the heated billets A to E are inserted into a cylindrical container (manufactured by JIS-SKD61, inner diameter (D _C ′) before preheating: 85 mm) of the extrusion molding apparatus shown in FIG. Hot extrusion was performed to produce a solid extruded material (second step).
In the hot extrusion molding described above, the billets A to E are heated to a hot working temperature of 1150 ° C. before the billets A to E are inserted into the container, and the container is also heated to a preheating temperature of 500 ° C., respectively. . In the billets A to E heated to the respective temperatures and the container, the distance between the inner peripheral surface of the billet and the outer peripheral surfaces of the billets A to E when the billets A to E are inserted into the container. The clearance (D _C -D _B ) between the outer diameter D _B (mm) of the billet A to E and the inner diameter D _C (mm) of the container is “1 mm” for the billet A and “ It was “4 mm” for billet C, “8 mm” for billet D, and “12 mm” for billet E.

As a result of hot extrusion molding, it was possible to extrude all of the effective portions of each of the billets B to D to the end without breaking the extruded material (diameter of about 27 mm in cross section).
On the other hand, in the case of billet A, when the billet is inserted into the container due to the fact that the above clearance is too small, the billet contacts the inner wall of the container and takes time (the billet temperature decreases). It was difficult to start hot extrusion. In the case of billet E, the smooth flow of the molten glass pad seems to be hindered due to the above clearance being too large, and as a result, the extruded extruded material shows signs of being divided. It was. And hot extrusion molding was stopped on the way.

FIG. 3 shows the appearance of an extruded material obtained from billet D (clearance: 8 mm) by the above hot extrusion molding. FIG. 4 shows the appearance of the extruded material obtained from billet E (clearance: 12 mm). 3 and 4, the right side is the tip of the extruded material (the die was located on the left side). The deposit observed on the surface of the extruded material is a solidified molten glass pad for lubrication.
On the surface of the extruded material in FIG. 3, a lubricating glass pad adhered from the front end to the rear end of the extruded material. The surface of the extruded material was free from cracks and no noticeable wrinkles were observed, indicating a good surface condition. And this favorable surface state was the same also in the extruded material obtained from billet B (clearance: 2 mm) and billet C (clearance: 4 mm).
On the other hand, the lubricating glass pad did not adhere to the surface of the extruded material in FIG. 4 from the front end to the rear end of the extruded material. A lot of “necking” occurred on the surface of the extruded material before the extruded material was divided.

1 Billet 2 Container 3 Dummy block 4 Stem 5 Dice (including die holder)
6 Extruded material 7 Glass pad for lubrication

Claims (10)

The billet is heated to a hot working temperature, the billet heated to the hot working temperature is inserted into a container, a compressive force is applied to the billet inserted into the container, and the billet is inserted through a hole in a die installed in the container. In a hot extrusion molding method in which a billet is extruded and molded,
The hot extrusion molding method is based on direct extrusion in which a compressive force is applied to the billet from one end side of the container into which the billet is inserted, and the billet is extruded from a hole of a die installed on the other end side of the container. And
The hot extrusion molding method is by glass lubrication extrusion in which a lubrication glass pad is mounted between the die and the billet,
The billet has a component composition of a precipitation-strengthened Ni-based superalloy having an equilibrium precipitation amount of gamma prime at 700 ° C. of 40 mol% or more,
Adjust so that the relationship between the outer diameter D _B (mm) of the billet when inserted into the container and the inner diameter D _C (mm) of the container is (D _C −D _B ): 2 to 8 mm. A method for hot extrusion of a Ni-base superalloy, characterized in that. 2. The Ni-base superalloy according to claim 1, wherein the container has an inner diameter D _C (mm) of 60 to 180 mm. The billet is heated to a hot working temperature, the billet heated to the hot working temperature is inserted into a container, a compressive force is applied to the billet inserted into the container, and the billet is inserted through a hole in a die installed in the container. In a hot extrusion molding method in which a billet is extruded and molded,
The hot extrusion molding method is based on direct extrusion in which a compressive force is applied to the billet from one end side of the container into which the billet is inserted, and the billet is extruded from a hole of a die installed on the other end side of the container. And
The hot extrusion molding method is by glass lubrication extrusion in which a lubrication glass pad is mounted between the die and the billet,
The billet has a component composition of a precipitation-strengthened Ni-based superalloy having an equilibrium precipitation amount of gamma prime at 700 ° C. of 40 mol% or more,
The relationship between the outer diameter D _B ′ (mm) of the billet before heating to the hot working temperature and the inner diameter D _C ′ (mm) of the container before heating to the preheating temperature is expressed as (D _C ′ −D _B '): Hot extrusion molding method of Ni-base superalloy, characterized by adjusting to 3 to 9 mm. The inner diameter _{D C} of the container '(mm) is hot extrusion molding method of the Ni-base superalloy according to claim 3, characterized in that the 60 ~ 180 mm. The method for hot extrusion of a Ni-base superalloy according to any one of claims 1 to 4, wherein the hot working temperature is 1150 to 1180 ° C. A first step of heating the billet of the Ni-base superalloy to a hot working temperature;
A billet heated to the hot working temperature is inserted into a container, a compressive force is applied to the billet from one end side of the container, and the billet is extruded from a hole of a die installed on the other end side of the container. A second step of obtaining an extruded material of the base superalloy,
The billet of the Ni-base superalloy has a component composition of a precipitation-strengthened Ni-base superalloy having an equilibrium precipitation amount of gamma prime at 700 ° C. of 40 mol% or more,
A lubricating glass pad is mounted between the die and the billet, and the relationship between the outer diameter D _B (mm) of the billet when inserted into the container and the inner diameter D _C (mm) of the container is , (D _C -D _B ): A method for producing a Ni-base superalloy material extruded material, characterized in that the second step is performed while adjusting to 2 to 8 mm. The method for producing an extruded Ni-base superalloy according to claim 6, wherein an inner diameter D _C (mm) of the container is adjusted to 60 to 180 mm. A first step of heating the billet of the Ni-base superalloy to a hot working temperature;
A billet heated to the hot working temperature is inserted into a container, a compressive force is applied to the billet from one end side of the container, and the billet is extruded from a hole of a die installed on the other end side of the container. A second step of obtaining an extruded material of the base superalloy,
The billet of the Ni-base superalloy has a component composition of a precipitation-strengthened Ni-base superalloy having an equilibrium precipitation amount of gamma prime at 700 ° C. of 40 mol% or more,
A lubricating glass pad is mounted between the die and the billet, and the outer diameter D _B ′ (mm) of the billet before heating to the hot working temperature and the container before heating to the preheating temperature The Ni-based superalloy is characterized in that the second step is performed by adjusting so that the relationship with the inner diameter D _C ′ (mm) of (D _C ′ −D _B ′) is 3 to 9 mm Method for producing extruded material. An inner diameter _{D C} '(mm) of the container, 60 ~ Ni based method for producing a refractory alloy extruded material according to claim 8, characterized in that adjusting the 180 mm. The method for producing a Ni-based superalloy according to any one of claims 6 to 9, wherein the hot working temperature is 1150 to 1180 ° C.

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