JP2006016691A - Heat treatment method and heat treatment apparatus for solid alloy material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment method for easily producing an alloy material having high strength. <P>SOLUTION: The heat treatment method for a solid alloy material comprises: an initial heating stage S3 where liquid lithium in an initial heating tank is beforehand heated and held to a temperature higher than a solid solution temperature at which alloy components in the solid alloy material are dissolved in a solid solution and also lower than the melting point of the solid alloy material, and the solid alloy material is directly dipped into the liquid lithium in the initial heating tank and is held till the solid alloy material forms a solid solution; a lithium dipping-cooling stage S4 where the liquid lithium in a cooling tank is beforehand held to a temperature lower than the solid solution temperature, and, after the initial heating stage S3, the solid alloy material is directly dipped into the liquid lithium in the cooling tank and is cooled, so as to obtain a supersaturated solid solution; a second cooling stage S5 where, after the lithium dipping-cooling stage S4, the solid alloy material is cooled to a room temperature; and a reheating stage S6 where, after that, the solid alloy material is charged inside a reheating tank held to an aging temperature higher than the room temperature and is held. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  More particularly, the present invention relates to a heat treatment method and a heat treatment apparatus using liquid lithium.

  It has long been practiced to obtain desired mechanical properties of carbon steel and other alloys by heat treatment such as quenching and annealing.

  Titanium is light and high in strength, and has been rapidly expanded in recent years because of its high temperature resistance and corrosion resistance. The crystal structure of pure titanium is a dense hexagonal crystal (α phase) at room temperature, but undergoes an allotropic transformation at about 885 ° C. to form a body-centered cubic crystal (β phase). On the other hand, it is known that an alloy in which various metals are added to pure titanium changes its crystal structure in various ways by heat treatment, and the mechanical properties can change accordingly (see Non-Patent Document 1).

In a conventional heat treatment of a metal material, an electric furnace, a gas furnace or a vacuum furnace is generally used as a heating means, and water, oil or gas is generally used as a cooling means. In some cases, high-frequency heating, current heating, salt heating cooling, and heating and cooling with molten metal such as lead, tin, and gallium are performed. Furthermore, a technique for heat-treating a solid metal material using liquid metal sodium or potassium as a cooling fluid has been proposed (see Patent Documents 1 and 2).
JP 2000-345236 A JP 2002-12917 A Toshiyuki Suzuki and Yasuo Moriguchi, “Titanium Story (Revised Edition)”, Japanese Standards Association (1995), pp. 70-78

  In the conventional method of heating with a gas or an electric heater, a long time is required for heating, and it is difficult to uniformly heat the metal to be processed. In addition, high-frequency heating requires a high-frequency energizing jig that matches the shape of the part to be processed, resulting in high costs. In salt heating and cooling, handling and management of the salt is very difficult from the viewpoint of environmental conservation. Furthermore, heating and cooling with molten metals such as lead, tin, and gallium are costly to handle and manage from the viewpoint of preventing environmental pollution caused by heavy metals, and the surface of the parts to be processed is plated with these heavy metals. It adheres and takes time to remove. In addition, sodium and potassium have low boiling points of 881 ° C. and 756 ° C., respectively, and it is necessary to create a pressurized atmosphere for use as a heating medium at temperatures higher than that, and there is a risk of spontaneous ignition in the atmosphere.

  In general, it is required to increase the strength of a metal material by heat treatment. In particular, titanium has a great lightness (small specific gravity), and there is a strong demand for increasing its strength.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the new heat processing method and heat processing apparatus for manufacturing an alloy material with high intensity | strength easily.

  The present invention achieves the above object, and the invention according to claim 1 is a heat treatment method for a solid alloy material, wherein the liquid lithium in the initial heating tank is converted into a solid solution with the alloy component of the solid alloy material. The solid alloy is heated and held in advance at a temperature higher than the melting temperature of the solid solution and lower than the melting point of the solid alloy material, and the solid alloy material is directly immersed in the liquid lithium in the initial heating tank. An initial heating step for holding the material until it forms a solid solution, and liquid lithium in the cooling bath is held in advance at a temperature lower than the solid solution temperature, and after the initial heating step, in the liquid lithium in the cooling bath Lithium immersion cooling step for directly immersing and cooling the solid alloy material to obtain a supersaturated solid solution, and after the lithium immersion cooling step, the reheating bath maintained at an aging temperature higher than room temperature. Having a reheating step of holding put the body alloy material, and characterized.

  The invention according to claim 2 is the heat treatment method according to claim 1, wherein the solid alloy material is cooled to a temperature lower than the melting point of lithium between the lithium immersion cooling step and the reheating step. 2. A heat treatment method for a solid alloy material, further comprising two cooling steps.

  The invention according to claim 3 is the heat treatment method according to claim 1 or 2, wherein the solid alloy material is an α-β titanium alloy material or a β titanium alloy material.

  The invention according to claim 4 is the heat treatment method according to claim 3, wherein in the initial heating step, the temperature of the liquid lithium in the initial heating tank is maintained at 700 ° C. or higher and 1300 ° C. or lower. The lithium immersion cooling step is performed by maintaining the temperature of the liquid lithium in the cooling bath at 500 ° C. or lower.

  The invention according to claim 5 is the heat treatment method according to any one of claims 1 to 4, wherein the solid alloy material is machined after the lithium immersion cooling step and before the reheating step. It further has the machining process before reheating to perform.

  The invention according to claim 6 is the heat treatment method according to any one of claims 1 to 5, further comprising a pre-heating machining step for machining the solid alloy material before the initial heating step. It is characterized by having.

  The invention according to claim 7 is the heat treatment method according to any one of claims 1 to 6, wherein in the reheating step, the solid alloy material is directly immersed in liquid lithium in the reheating tank. It is characterized by being performed.

  According to an eighth aspect of the present invention, there is provided a heat treatment apparatus for an alloy material, comprising: a heat treatment chamber filled with an inert gas; and a solid solution in which the alloy components of the solid alloy material are dissolved in a solid solution. The liquid lithium is heated and held at a temperature higher than the melting temperature and lower than the melting point of the solid alloy material, and an initial heating tank for receiving the solid alloy material in the liquid lithium is disposed in the heat treatment chamber. The liquid lithium is held at a temperature lower than the solid solution temperature, and the liquid lithium has a cooling tank that receives the solid alloy material that has passed through the initial heating tank. .

  The invention according to claim 9 is the heat treatment apparatus for a solid alloy material according to claim 8, wherein the alloy material is an α-β titanium alloy material or a β titanium alloy material.

  The invention according to claim 10 is the heat treatment apparatus for solid alloy material according to claim 8 or 9, wherein the solid lithium material is disposed in the heat treatment chamber, is lower than the solid solution temperature, and is liquid lithium in the cooling bath. The liquid lithium is further maintained at a higher temperature, and the liquid lithium further includes a reheating tank that receives the solid alloy material that has passed through the cooling tank.

  The invention according to claim 11 is the heat treatment apparatus for a solid alloy material according to any one of claims 1 to 7, wherein the solid alloy material is a titanium alloy material. It is a material of any one of a structural member, an aircraft structural member, an engine structural member, and an implant member.

  According to the present invention, it is possible to easily carry out rapid heating and cooling, which has not been conceived in the past, to solid alloy materials, thereby dramatically increasing the strength of the alloy materials. it can. In particular, the liquid metal lithium used here has the following advantages when used for heat treatment of a solid alloy material.

  (1) Since the boiling point of lithium (1342 ° C.) is higher than the boiling point of sodium (881 ° C.), heat treatment at a higher temperature is possible with liquid metallic lithium.

  (2) Since it is liquid and has high thermal conductivity, uniform heating is possible.

  (3) Since the amount of vapor generated is smaller than that of liquid metal sodium, the consumption of lithium is small.

  (4) Lithium adhering to the surface can be easily removed by washing with water.

  (5) Compared with liquid metallic sodium, the reaction with water is gentle and easy to handle.

  (6) Since the specific gravity is about half as small as that of liquid metallic sodium, transportation and handling are easy.

  (7) Oxidation in air is milder than liquid metal sodium and does not ignite spontaneously, so it is easy to handle.

  (8) When the solid alloy material to be treated is titanium, it functions to reduce the oxide on the titanium surface and clean the surface. (Because lithium is easier to oxidize than titanium.)

  Embodiments of a heat treatment method and a heat treatment apparatus for a solid alloy material according to the present invention will be described below with reference to FIGS. Here, FIG. 1 is a flowchart showing an embodiment of a heat treatment method for a solid alloy material according to the present invention, and FIG. 2 is a schematic sectional elevation view showing an embodiment of a heat treatment apparatus for a solid alloy material according to the present invention. FIG. 3 is a graph showing an example of a temperature change of the solid metal material to be treated when the solid metal material to be treated is an α-β titanium alloy in the heat treatment method of FIG.

  As shown in FIG. 2, three liquid lithium baths 12, 14, and 16 are disposed in a heat treatment chamber 10 for heat treating a solid metal material (for example, an α-β titanium alloy or a metal lump of β titanium alloy) 50. ing. These are the initial heating tank 12, the cooling tank 14, and the reheating tank 16. The temperature of the liquid lithium accommodated in the initial heating tank 12 is previously maintained at a temperature (transformation temperature) that is higher than the solid solution temperature of the solid alloy material to be treated and lower than the melting point of the solid alloy material. Here, the solid solution temperature is a temperature at which the alloy component of the solid alloy material to be processed is dissolved in the solid solution. For example, when the solid alloy material to be treated is an α-β titanium alloy, it is preferably maintained in the range of 700 to 1000 ° C. For this purpose, a heater 18 for heating lithium is attached to the initial heating tank 12.

  Moreover, the temperature of the liquid lithium accommodated in the cooling tank 14 is kept at a cooling temperature lower than the solid solution temperature of the solid alloy material to be processed and higher than the melting point (181 ° C.) of lithium. For example, when the solid alloy material to be treated is an α-β titanium alloy, the cooling temperature is preferably maintained at a temperature of 500 ° C. or lower, and more preferably within a range of 181 to 300 ° C. For this purpose, a heater 20 for heating liquid lithium and a fan 22 for cooling the heater 20 are attached to the cooling tank 14.

  The temperature of the liquid lithium accommodated in the reheating tank 16 is preferably maintained at a temperature higher than the melting point (181 ° C.) of lithium, for example, 200 to 650 ° C., and more preferably in the range of 300 to 600 ° C. Is preferably maintained. For this purpose, a heater 24 for heating liquid lithium is attached to the reheating tank 16.

  The heat treatment chamber 10 is filled with an inert gas that does not react with liquid lithium. The entrance door 30 and the exit door 32 are doubled, and an entrance chamber 34 and an exit chamber 36 are formed between the double doors. With this structure, the solid metal material 50 can be put into and out of the heat treatment chamber 10 while the liquid lithium baths 12, 14 and 16 are maintained in an inert gas atmosphere.

  The heat treatment chamber 10 is provided with a moving mechanism 38 for sequentially immersing and moving the solid metal material 50 in the liquid lithium in the liquid lithium baths 12, 14, and 16.

  Next, an embodiment of the heat treatment method for the solid alloy material according to the present invention will be described along the flowchart shown in FIG.

  First, in the first step S1, a solid metal material such as a titanium alloy that is a material to be treated is rolled to a predetermined thickness by a rolling roll or the like to form a plate material, or a metal lump is cut or molded. By doing so, it is machined to a predetermined part shape dimension. By this process, processing strain is accumulated inside the metal, which helps to create nuclei that form a fine structure by the subsequent heat treatment, thereby increasing the strength of the material. In addition, in FIG. 2, the example which processes the metal lump 50 as a solid metal material is shown.

  Subsequently, in the second step S2, dirt and impurities attached to the surface of the solid metal material are removed. This step is important in managing the purity of liquid lithium.

  Next, the solid metal material (metal lump) 50 is carried into the heat treatment chamber 10 through the inlet chamber 34 and immersed in the liquid lithium in the initial heating tank 12 in the third step S3. Thereby, the solid metal material 50 is rapidly heated to a temperature higher than the solid solution temperature. At this time, the alloy component dissolves over the entire structure almost instantaneously to form a solid solution.

  Moreover, the growth of crystal grain size is suppressed by rapid heating and short-time heating. That is, when the solid metal material to be treated is, for example, an α-β titanium alloy, it changes from an α phase that is a dense hexagonal crystal to a β crystal that is a body-centered cubic crystal, but growth of the particle size of the β crystal is suppressed.

  Next, the solid metal material 50 is taken out from the initial heating tank 12 and immersed in liquid lithium in the cooling tank 14 in the fourth step S4. Thereby, the solid metal material 50 is rapidly cooled to a temperature lower than the solid solution temperature at which the alloy component is dissolved in the solid solution. This rapid cooling suppresses the growth of the α structure of the alloy element, maintains the supersaturated β structure, and forms a state in which the alloy element is more finely dissolved in the structure.

  Next, the solid metal material 50 is taken out of the liquid lithium in the cooling bath 14, and is cooled to a temperature lower than the melting point of lithium in a fifth step (second cooling step) S5. For example, it is cooled to room temperature (normal temperature) by natural cooling in gas. In this step, the structure is stabilized by keeping it at room temperature for a predetermined time. Note that the fifth step S5 is not limited to natural cooling, and may be forced cooling or the like. Further, the fifth step S5 can be omitted.

  Furthermore, after the completion of the fourth step S4 or the fifth step S5, the solid metal material 50 is subjected to mechanical processing such as rolling, and strain is added to the inside of the metal, thereby making it possible to refine the structure. Yes (not shown). In particular, since the solid metal material 50 is relatively soft at this time, it is convenient for machining.

  Next, in the sixth step S6, the solid metal material 50 is immersed in the liquid lithium in the reheating tank 16 and reheated. In this step, a compound structure is formed between the metal and the alloy element by aging. At that time, the structure becomes finer, and as a result, the strength is improved.

  Next, the solid metal material 50 is carried out of the heat treatment chamber 10 through the outlet chamber 36. Next, it cools to normal temperature by 7th process S7. This cooling is, for example, by natural cooling in a gas atmosphere at room temperature.

  Next, in the eighth step S8, lithium attached to the solid metal material 50 is removed. This step can be performed by washing with water or ultrasonic waves.

  In the above example, after the solid metal material 50 is carried out of the heat treatment chamber 10, the seventh step S7 (natural cooling) and the eighth step S8 (removal of attached lithium / surface cleaning) are performed. This step can also be performed in the heat treatment chamber 10.

  In addition, since the sixth step S6 (reheating) does not necessarily need to be performed rapidly, reheating may be performed by another method such as electric furnace or vacuum furnace heating instead of in liquid lithium. In that case, the solid metal material 50 can be carried out of the heat treatment chamber 10 before the sixth step S6 (reheating).

  2 shows the case where the solid metal material 50 is in the form of a metal lump, the solid metal material may be a wire or a plate. In this case, the continuous solid metal material is the initial heating tank 12 or the cooling tank. 14. Heat treatment can be performed continuously (not shown) by sequentially passing through the reheating tank 16. Although not shown in FIG. 2, the heat treatment chamber 10 can be made into a glove box type and can be manually performed by an operator instead of the moving mechanism 38.

  As described above, a metal material with extremely high strength can be obtained through a series of heat treatments using liquid lithium, through rapid heating, cooling, and reheating.

  Here, an application example of the titanium alloy material subjected to the above-described heat treatment will be described. Each of these application examples utilizes the fact that the specific gravity of the titanium alloy is small and that high strength can be obtained by this heat treatment.

[Application to golf club head materials]
The most important performance required for designing and manufacturing a golf club is that the hit distance of the hit ball is large. For this purpose, it is important to make the club head as light as possible, to make the head speed as high as possible when swinging, and to increase the coefficient of restitution on the face surface where the ball hits. Conventionally, the face surface has been made as hard as possible, and the resilience coefficient has been increased by utilizing the elasticity of the ball. Recently, it has been found that increasing the resilience coefficient of the face surface increases the resilience coefficient, increasing the resilience. Therefore, there is a demand for a club having a thinner face.

  FIG. 4 shows a calculation example showing the relationship between the thickness of the face and the amount of deflection of the face in the club head. It can be seen that the amount of deflection increases as the face becomes thinner. Therefore, it is desirable to make the face as thin as possible in order to increase the coefficient of restitution. However, when the face is thinned, the stress generated in the face material due to impact such as when a ball hits becomes large, so higher material strength is required.

  In response to these demands, titanium alloys have recently been used as club head materials. However, because titanium alloys are very active and highly reactive, it is difficult to remove a thick oxide film on the surface during conventional heat treatment during heating and cooling, and the temperature distribution of the heat treatment furnace varies. Since the variation in quality greatly affects the variation in quality, the temperature control of the conventional heat treatment furnace is insufficient, and is not generally adopted for titanium alloys used for golf clubs.

  In addition, although a heat-treated titanium alloy is partially used, hydrogen and oxygen easily diffuse and penetrate into the interior during high-temperature heating in conventional heat treatment, and sufficient strength improvement cannot be obtained.

  By performing the heat treatment according to the present invention, the strength of the titanium alloy material can be further increased than before, and a thinner and stronger golf club head can be realized. Thereby, a larger flight distance can be obtained.

  FIG. 5 shows a structural example of a wood type golf club head using a titanium alloy material subjected to heat treatment according to the present invention. The golf club head has a hollow structure, a hosel 60 connected to a shaft (not shown), a crown 62 joined to the hosel 60 to form an upper portion of the hollow portion 61, and a hollow connected to the crown 62. A sole 63 that forms the bottom of the portion 61, and a face 64 that is connected to the crown 62 and the sole 63 and forms the front surface of the hollow portion 61. These parts are welded together. The face 64 is a plate-like portion that hits a ball (not shown), and has a function of bending when the ball hits, and then repelling the ball by the elasticity of the face 64.

  As a material of this golf club head, a titanium alloy material subjected to heat treatment according to the present invention is used. That is, since this material has a strength higher than that of a conventional titanium alloy material, it is possible to reduce the pressure of the body, thereby making the club head lighter than in the past.

  In particular, by using this material for the face 64 to reduce the body pressure, not only can the club head be reduced in weight, but also the deflection of the face 64 when the face 64 hits the ball can be increased. The coefficient of restitution can be increased. Therefore, it is also effective to use a titanium alloy material that has been heat-treated according to the present invention only on the face 64.

[Application to machine structural materials]
Titanium alloys have a high specific strength (strength per unit density), so titanium alloys are being used as mechanical structural materials to reduce the weight of automobile bodies, airplane fuselages, wings, engines, etc. Yes. Since the titanium alloy material subjected to the heat treatment according to the present invention has a higher specific strength than the conventional titanium alloy, it can be applied to such applications.

  FIG. 6 is a cross-sectional view of an automobile gasoline engine which is an application example of the solid alloy material heat treatment method according to the present invention. The piston 72 in the cylinder 71 is connected to the crankshaft 74 via the connecting rod 73, and the crankshaft 74 is rotationally driven by the piston 72 reciprocating in the cylinder 71. An intake pipe 76 and an exhaust pipe 77 are connected to the cylinder head 75 in the upper part of the cylinder 71, and an intake valve 78 and an exhaust valve 79 are arranged to open and close the intake pipe 76 and the exhaust pipe 77, respectively. The opening / closing timing of the intake valve 78 and the exhaust valve 79 is determined by the rotation of the cam 80 and the valve rocker 81, and the pressing force of the cam 80 is controlled by the valve spring 82 and the retainer 83.

  Therefore, lightening the valves 78 and 79, the valve spring 82, the retainer 83, the connecting rod 73, the piston 72, etc., which are constantly reciprocating, to reduce the inertial force greatly contributes to the improvement of the engine performance. Therefore, it is effective to apply the solid alloy material heat treatment method according to the present invention to at least some of these components.

  FIG. 7 is a longitudinal sectional view of an airplane jet engine which is an application example of the solid alloy material heat treatment method according to the present invention. The air in the front is collected by the fan blade 87, and a part of the collected air is made high pressure in the compression zone 40 and sent to the combustion chamber 41 behind it, where it is mixed with fuel and burned to produce high-temperature and high-pressure combustion gas. Then, the turbine 42 behind is rotated. It is effective to apply the solid alloy material heat treatment method according to the present invention to the fan blade 87, the compressor blade 88 and the compressor blade disk 89 which are movable parts in the low temperature region, the fan case 90 and the vane 91 in the stationary part. It is.

  In this way, by applying the solid alloy material heat treatment method according to the present invention to aircraft jet engine components, the entire aircraft can be reduced in weight, and the centrifugal force can be reduced by reducing the rotating components. As a result, higher speed rotation is possible, which contributes to improved engine performance.

[Application to implant materials]
Titanium alloys are generally light and strong, and do not cause harm such as toxicity to the human body. Therefore, titanium alloys are used as implant materials that are embedded in the human body as part of an artificial bone. Since the titanium alloy material subjected to the heat treatment according to the present invention has a higher specific strength than the conventional titanium alloy, it can be applied to such applications.

  FIG. 8 is a developed longitudinal sectional view of an artificial hip joint which is an application example of the heat treatment method for a solid alloy material according to the present invention. A spherical lid portion 94 made of a titanium alloy having excellent coexistence with the human body and a ceramic or resin material having excellent wear resistance is embedded (implanted) in the hip bone 95, and the concave portion 99 is embedded in the spherical lid portion 94. Is formed. In addition, a stem portion 98 made of titanium alloy is embedded in the femur 97, and a bone head 96 made of titanium alloy protrudes from the stem portion 98. A bone head 96 is slidably inserted into the concave portion 99 of the spherical lid portion 94 to form an artificial hip joint. By controlling physical properties such as elongation and Young's modulus of the titanium alloy so as to be close to human bones, a comfortable artificial joint closer to human bones can be obtained.

  By applying the heat treatment method of the solid alloy material according to the present invention, the range in which the physical property value of the titanium alloy can be controlled is widened, and a physical property value closer to human bones can be obtained.

  FIG. 9 shows the result of the heat treatment shown in FIGS. 1 and 3 for Ti-6Al-4V, which is an α-β titanium alloy.

  That is, FIG. 9 shows measured values of 0.2% proof stress and tensile strength before and after the heat treatment. Furthermore, the value published in Table 4.3 on page 76 of Non-Patent Document 1 is also shown as a value after solution aging treatment by a conventional method. As is apparent from this table, according to the heat treatment method of the present invention, the proof stress and strength of the metal material to be treated are remarkably increased.

The flowchart which shows one Embodiment of the heat processing method of the solid alloy material which concerns on this invention. 1 is a schematic sectional elevation showing an embodiment of a heat treatment apparatus for a solid alloy material according to the present invention. The graph which shows an example of the temperature change of a to-be-processed solid metal material when the to-be-processed solid metal material is made into (alpha) -beta titanium alloy in the heat processing method of FIG. The graph which shows the relationship between the face thickness of a golf club head, and the amount of bending. The longitudinal cross-sectional view of the golf club head which is an application example of the heat processing method of the solid alloy material which concerns on this invention. Sectional drawing of the gasoline engine which is an application example of the heat processing method of the solid alloy material which concerns on this invention. The longitudinal cross-sectional view of the jet engine which is an example of application of the heat processing method of the solid alloy material which concerns on this invention. The expansion | deployment longitudinal cross-sectional view of the artificial hip joint which is an example of application of the heat processing method of the solid alloy material which concerns on this invention. The table | surface which shows the actual value of the proof stress and intensity | strength of the Example of Ti-6Al-4V material by the heat processing method of FIG. 1 and FIG.

Explanation of symbols

10: Heat treatment chamber, 12: Initial heating bath (liquid lithium bath), 14: Cooling bath (liquid lithium bath), 16: Reheating bath (liquid lithium bath), 18: Heater, 20: Heater, 22: Fan, 24 : Heater, 30: inlet door, 32: outlet door, 34: inlet chamber, 36: outlet chamber, 38: moving mechanism, 40: compression zone, 41: combustion chamber, 42: turbine, 50: solid metal material (metal lump) ), 60: hosel, 61: hollow part, 62: crown, 63: sole, 64: face, 71: cylinder, 72: piston, 73: connecting rod, 74: crankshaft, 75: cylinder head, 76: intake pipe, 77: exhaust pipe, 78: intake valve, 79: exhaust valve, 80: cam, 81: valve rocker, 82: valve spring, 83: retainer, 87: fan blade, 88: compressor Blade, 89: compressor blade disc, 90: fan case, 91: vane, 94: Tamafuta unit, 95: hip, 96: bone head, 97: femur, 98: stem portion, 99: concave portion

Claims (11)

A heat treatment method for a solid alloy material,
The liquid lithium in the initial heating tank is preheated and held at a temperature higher than the solid solution temperature at which the alloy component of the solid alloy material dissolves in the solid solution and lower than the melting point of the solid alloy material. An initial heating step of directly immersing the solid alloy material in liquid lithium and holding the solid alloy material until a solid solution is formed;
The liquid lithium in the cooling tank is held in advance at a temperature lower than the solid solution temperature, and after the initial heating step, the solid alloy material is directly immersed in the liquid lithium in the cooling tank and cooled to obtain a supersaturated solid solution. A lithium immersion cooling step to obtain,
After the lithium immersion cooling step, a reheating step of holding and holding the solid alloy material in a reheating tank maintained at an aging temperature higher than room temperature,
A method for heat treatment of a solid alloy material characterized by comprising:   2. The heat treatment method according to claim 1, further comprising a second cooling step of cooling the solid alloy material to a temperature lower than a melting point of lithium between the lithium immersion cooling step and the reheating step. A heat treatment method for a solid alloy material.   The heat treatment method according to claim 1 or 2, wherein the solid alloy material is an α-β titanium alloy material or a β titanium alloy material. In the heat processing method of Claim 3,
The initial heating step is performed by maintaining the temperature of liquid lithium in the initial heating tank at 700 ° C. or higher and 1300 ° C. or lower,
The lithium immersion cooling step is performed while maintaining the temperature of liquid lithium in the cooling bath at 500 ° C. or lower.
A heat treatment method for a solid alloy material.   5. The heat treatment method according to claim 1, further comprising a pre-reheating machining step of machining the solid alloy material after the lithium immersion cooling step and before the reheating step. A heat treatment method for a solid alloy material characterized by the above.   The heat treatment method according to any one of claims 1 to 5, further comprising a pre-heating machining step of machining the solid alloy material before the initial heating step. Heat treatment method.   The heat treatment method according to any one of claims 1 to 6, wherein the reheating step is performed by directly immersing the solid alloy material in liquid lithium in the reheating tank. Heat treatment method. In heat treatment equipment for alloy materials,
A heat treatment chamber filled with an inert gas,
The liquid lithium disposed in the heat treatment chamber is heated and held at a temperature higher than a solid solution temperature at which an alloy component of the solid alloy material dissolves in a solid solution and lower than a melting point of the solid alloy material. An initial heating tank for receiving the solid alloy material in the interior;
A cooling tank that is disposed in the heat treatment chamber, holds liquid lithium at a temperature lower than the solid solution temperature, and receives the solid alloy material that has passed through the initial heating tank in the liquid lithium;
A heat treatment apparatus for a solid alloy material, comprising:   9. The heat treatment apparatus for a solid alloy material according to claim 8, wherein the alloy material is an α-β titanium alloy material or a β titanium alloy material.   The heat treatment apparatus for a solid alloy material according to claim 8 or 9, wherein the liquid lithium is disposed in the heat treatment chamber, and the liquid lithium is held at a temperature lower than the solid solution temperature and higher than the liquid lithium in the cooling bath. In addition, the liquid lithium further includes a reheating tank that receives the solid alloy material that has passed through the cooling tank. The solid alloy material is a titanium alloy material, and is any one of a golf club head member, a vehicle structural member, an aircraft structural member, an engine structural member, and an implant member. Item 8. A heat treatment method for a solid alloy material according to any one of Items 1 to 7.

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