Tantalum-tungsten alloy hot forging processing method

Abstract

The invention provides a tantalum-tungsten alloy hot forging machining method. The method comprises the following steps that a tantalum-tungsten alloy prefabricated part is subjected to heat preservation and then subjected to hot forging machining; the tantalum-tungsten alloy prefabricated part comprises a tantalum-tungsten alloy inner core, glass powder and a metal sheath layer from inside to outside; the heat preservation temperature ranges from 900 DEG C to 1400 DEG C. According to the method, heat preservation and hot forging are conducted after the tantalum-tungsten alloy prefabricated part is formed, and in the heat preservation process, the glass powder and the metal wrapping layer effectively prevent oxygen from invading; the glass powder can automatically fall off in the hot forging process, so that the steps of hot forging processing are simplified; through the treatment, oxidation of the large-size tantalum-tungsten alloy in the heating process is prevented, and the boundary dimension and the surface effect of the blank subjected to hot forging have good controllability.

Description

Technical Field

[0001] The present application relates to the technical field of alloy processing, and in particular to a hot forging method for tantalum-tungsten alloy. Background Art

[0002] Tantalum is a highly active metal that easily absorbs oxygen when exposed to air above 300°C. Tantalum-based alloys have poor oxidation resistance and begin to oxidize at 400°C. Tantalum-tungsten alloys are mostly produced by electron beam melting. The ingots obtained by the melting method have coarse grains and generally require forging to break the grains. Tantalum-tungsten alloys have high strength, and the forging stage is often carried out at a temperature above 800°C. High-temperature oxidation causes severe burning of the material during forging, affecting the forging performance of the material, reducing the material yield, and worsening the surface condition of the forging, further causing adverse effects on subsequent processing.

[0003] At present, the forging of tantalum-tungsten alloy ingots adopts the method of rapid heating by induction heating and then forging. During the heating process, the material is directly exposed to the atmosphere and continuously oxidized, which is not suitable for the forging of large-sized (greater than 20kg) ingots. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and its purpose is to provide a tantalum-tungsten alloy hot forging method, which has excellent high-temperature oxidation resistance effect.

[0005] Specifically, the present invention provides a tantalum-tungsten alloy hot forging method, comprising the following steps: Hot forging the tantalum-tungsten alloy preform after keeping it warm; The tantalum-tungsten alloy preform comprises a tantalum-tungsten alloy core, glass powder and a metal sheath layer from the inside to the outside; The insulation temperature is 900°C to 1400°C.

[0006] According to one technical solution of the hot forging method technical solution of the present application, at least the following beneficial effects are achieved: The present application forms a tantalum-tungsten alloy preform and then performs heat preservation and hot forging. During the heat preservation process, the glass powder and the metal sheath layer effectively prevent the intrusion of oxygen; and the glass powder can fall off by itself during the hot forging process, simplifying the steps of the hot forging process; through the above-mentioned treatment, the oxidation of large-sized tantalum-tungsten alloy during the heating process is prevented, and the external dimensions and surface effects of the blank after hot forging have good controllability.

[0007] The present application forms a glass powder and a metal sheath layer on the surface of the tantalum-tungsten alloy core; wherein the metal sheath layer isolates the external oxygen, and the glass powder on the surface of the tantalum-tungsten alloy core further densely isolates the surface of the tantalum-tungsten alloy core, thereby achieving double-layer oxygen isolation protection.

[0008] And because there is glass powder between the tantalum tungsten alloy core and the metal sheath layer in the tantalum tungsten alloy preform, there is a gap between the metal sheath layer and the internal tantalum tungsten alloy core; in the subsequent hot forging process, the metal sheath layer will not adhere to the surface of the tantalum tungsten alloy core after hot forging, so that the metal sheath layer can fall off by itself during the hot forging process, and no further lathe processing is required after the hot forging process, which simplifies the hot forging process steps of the tantalum tungsten alloy and the final hot forged slab has a good surface effect.

[0009] According to some embodiments of the present application, the operating temperature of the glass powder is 850°C~1400°C.

[0010] Glass powder has stable performance and is non-toxic. It can form a barrier between the sheath layer and the tantalum-tungsten alloy core. It has a secondary anti-oxidation protection during the heating process. It can also facilitate the spontaneous rupture and fall-off of the sheath layer during the hot forging process. It does not affect the reversing forging during the alloy hot forging process, and is conducive to the precise control of the shape and size of the finished forging.

[0011] According to some embodiments of the present application, the melting point of the metal sheath layer is ≥ the insulation temperature.

[0012] According to some embodiments of the present application, the metal sheath layer includes a stainless steel layer.

[0013] According to some embodiments of the present application, the tantalum-tungsten alloy core is made by electron beam melting.

[0014] The tantalum-tungsten alloy ingot in the present application is obtained by electron beam melting. Due to the characteristics of its metallographic structure, the conditions required for the sheathing treatment are simple and the operation process is convenient. In addition, the tantalum-tungsten alloy obtained by the electron beam melting method is large in size and weight. After heat preservation and then hot forging treatment, large-sized and heavy-weight tantalum-tungsten alloy forging products can be obtained at one time; further avoiding the defects of severe burning during forging and low material yield in small-sized and small-batch tantalum-tungsten alloy forging.

[0015] According to some embodiments of the present application, the tantalum-tungsten alloy core is cylindrical.

[0016] According to some embodiments of the present application, the diameter of the tantalum-tungsten alloy core is 100 mm to 300 mm.

[0017] According to some embodiments of the present application, the diameter of the tantalum-tungsten alloy core is 150 mm to 300 mm.

[0018] According to some embodiments of the present application, the length of the tantalum-tungsten alloy core is 100 mm to 500 mm.

[0019] According to some embodiments of the present application, the mass of the tantalum-tungsten alloy core is above 20 kg.

[0020] According to some embodiments of the present application, the mass of the tantalum-tungsten alloy core is 20kg~1000kg.

[0021] According to some embodiments of the present application, the mass of the tantalum-tungsten alloy core is 50kg~1000kg.

[0022] According to some embodiments of the present application, the mass of the tantalum-tungsten alloy core is 200kg~1000kg.

[0023] According to some embodiments of the present application, the mass fraction of tungsten in the tantalum-tungsten alloy core is 2% to 15%.

[0024] Normally, when the tungsten content in the tantalum-tungsten alloy ingot is less than 2%, hot deformation is not required; when the tungsten content in the tantalum-tungsten alloy ingot is greater than 15%, the hot deformation temperature is expected to be greater than 1400℃. At this time, the metal sheath used for hot working will melt more easily, resulting in rupture of the sheath, and it is impossible to ensure the oxygen isolation effect of the tantalum-tungsten alloy ingot before completing the hot forging process.

[0025] According to some embodiments of the present application, the thickness of the metal sheath layer is 2 mm to 10 mm.

[0026] According to some embodiments of the present application, the insulation time is 0.5h~10h.

[0027] According to some embodiments of the present application, the parameters of the hot forging process are as follows: The initial forging temperature is 900℃~1400℃.

[0028] According to some embodiments of the present application, the initial forging temperature during the hot forging process is 900°C-1400°C, and the steel is forged first in the axial direction with a deformation rate of 20%~50%, and then squaring is performed. After squaring, forging is continued in the thickness direction to a thickness of 40mm~120mm.

[0029] According to some embodiments of the present application, the metal sheath layer is a stainless steel layer.

[0030] The minimum heating temperature required for the forging of tantalum-tungsten alloy is not less than 900℃, and the maximum temperature that the stainless steel sheath can withstand is generally not more than 1400℃; therefore, this temperature range is preferred so that the tantalum-tungsten alloy can meet the forging requirements and the stainless steel sheath will not melt and fall off prematurely; therefore, the oxygen isolation effect of tantalum-tungsten alloy forging is better under this temperature environment.

[0031] According to some embodiments of the present application, the stainless steel is 304 stainless steel.

[0032] According to some embodiments of the present application, the method for preparing the tantalum-tungsten alloy preform comprises the following steps: After glass powder is formed on the surface of the tantalum-tungsten alloy core, metal sheathing treatment is performed to form a tantalum-tungsten alloy preform.

[0033] According to some embodiments of the present application, the metal encapsulation process is vacuum encapsulation or non-vacuum encapsulation.

[0034] Since the tantalum-tungsten alloy in the present application is a fully dense material obtained by electron beam melting, it can basically meet the requirements by performing a sheathing treatment in a non-vacuum atmospheric environment and then performing a hot forging treatment; and vacuum sheathing is conducive to further controlling impurities and obtaining excellent results.

[0035] According to some embodiments of the present application, the method for preparing the tantalum-tungsten alloy core comprises the following steps: The tantalum-tungsten alloy ingot is sawn and then polished.

[0036] In the present application, during the process of preparing tantalum-tungsten alloy hot-forged preforms, the tantalum-tungsten alloy ingots prepared by electron beam melting are sawed and polished, with the aim of facilitating subsequent coating and sheathing treatments; and polishing the surface can better ensure the coating effect.

[0037] According to some embodiments of the present application, the insulation temperature is 900°C~1300°C.

[0038] According to some embodiments of the present application, the insulation time in the morning is 2h~10h.

[0039] The present application has concluded through further test data that the forging of tantalum-tungsten alloy after stainless steel sheathing at a temperature below 1300°C is more economical and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present drawings or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0041] Figure 1 This is a physical picture of the tantalum-tungsten alloy slab prepared in Example 1; Figure 2 This is a physical picture of the tantalum-tungsten alloy slab prepared in Example 2; Figure 3 This is a physical picture of the tantalum-tungsten alloy slab prepared in Comparative Example 1; Figure 4 This is a physical picture of the tantalum-tungsten alloy slab prepared in Comparative Example 2.

[0042] The purpose, features and advantages of this figure will be further described in conjunction with the embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0044] Obviously, the following descriptions are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in the field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0045] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0046] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0047] The method for preparing the tantalum-tungsten alloy ingot selected in the examples and comparative examples of the present application comprises the following steps: The tantalum-tungsten alloy bars prepared by powder metallurgy are prepared into tantalum-tungsten alloy ingots (the mass fraction of tungsten is 11.5%) by secondary electron beam melting.

[0048] The use temperature of the anti-oxidation glass powder selected in the embodiment of the present application is 850°C~1400°C.

[0049] Example 1 A tantalum-tungsten alloy hot forging method, comprising the following steps: S1. Process the tantalum-tungsten alloy ingot to a size of Ф195mm×456mm and a weight of 223.05kg; S2, coating the surface of the tantalum-tungsten alloy ingot processed by lathe with anti-oxidation glass powder evenly; S3, the coated tantalum-tungsten alloy ingots are respectively treated with 304 stainless steel sheaths in an atmospheric environment; the thickness specification is 3 mm, and tantalum-tungsten alloy preforms are respectively formed; S4, placing the tantalum-tungsten alloy preform in a heating furnace at 1150° C. for 4 hours; S5. The tantalum-tungsten alloy preform that has been heat-insulated is hot forged to obtain a tantalum-tungsten alloy slab. The parameters of the hot forging process in this embodiment are as follows: the initial forging temperature is 1150°C, the axial forging is performed first, the deformation rate is 50%, and then the forging is reversed to square, and after squared, the forging is continued along the thickness direction to a thickness of 75mm-80mm, and then squared.

[0050] The slab size is 390mm in length, 340mm in width, 75mm~80mm in thickness, and the weight after forging is 219.7kg. Figure 1 As shown, oxidation is better during forging.

[0051] Example 2 A tantalum-tungsten alloy hot forging method, comprising the following steps: S1. Process the tantalum-tungsten alloy ingot to a size of Ф190mm×449mm and a weight of 209.05kg; S2, coating the surface of the tantalum-tungsten alloy ingot processed by lathe with anti-oxidation glass powder evenly; S3, treating the coated tantalum-tungsten alloy ingot with a stainless steel sheath in an atmospheric environment; the stainless steel sheath is made of 304 stainless steel with a thickness of 3 mm, to form a tantalum-tungsten alloy preform; S4, placing the encapsulated tantalum-tungsten alloy preform in a heating furnace at 1250° C. for 4 hours; S5, hot forging the tantalum-tungsten alloy ingot after heat preservation to obtain a tantalum-tungsten alloy slab; The parameters of hot forging in this embodiment are as follows: The initial forging temperature is 1250℃. Forging is performed along the axial direction with a deformation rate of 50%. Then the forging direction is changed to square. After squareness, forging is continued along the thickness direction until the slab size is 370mm in length, 350mm in width, and 85mm~90mm in thickness. The weight after forging is 205.7kg. Figure 2 As shown, oxidation is better during forging.

[0052] Comparative Example 1 A tantalum-tungsten alloy hot forging method, comprising the following steps: S1. Process the tantalum-tungsten alloy ingot to a size of Ф190mm×455mm and a weight of 220.05kg; S2, placing the tantalum-tungsten alloy ingot in a heating furnace at 1150°C for 4 hours; S3, hot forging the tantalum-tungsten alloy ingot after heat preservation to obtain a tantalum-tungsten alloy slab; The parameters of hot forging in this comparative example are as follows: The initial forging temperature is 1150℃. The forging is first performed along the axial direction with a deformation rate of 50%. Then the forging direction is changed to square. After squareness, the forging is continued along the thickness direction until the slab size is 400mm in length, 350mm in width, and 76-80mm in thickness. The weight after forging is 203.7kg. Figure 3 As shown (the entire surface is yellow), there is severe oxidation during the forging process (and removing the oxide layer requires mechanical grinding, which increases the subsequent processing steps and greatly reduces the efficiency).

[0053] Comparative Example 2 A tantalum-tungsten alloy hot forging method, comprising the following steps: S1. Process the tantalum-tungsten alloy ingot to a size of Ф190mm×454mm and a weight of 221.05kg; S2. The tantalum-tungsten alloy round ingot processed by lathe is treated with stainless steel primary forging jacket in atmospheric environment without adding coating material; S3, placing the tantalum-tungsten alloy ingot in a heating furnace at 1150°C for 4 hours; S4, hot forging the tantalum-tungsten alloy ingot after heat preservation to obtain a tantalum-tungsten alloy slab; The parameters of hot forging in this comparative example are as follows: The initial forging temperature is 1150℃. The forging is first performed along the axial direction with a deformation rate of 50%. Then the forging direction is changed to square. After squareness, the forging is continued along the thickness direction until the slab size is 390mm in length, 380mm in width, and 85mm in thickness. The weight after forging is 230.7kg. Figure 4 As shown in the figure, after forging, the removal effect of the sleeve and the ingot is poor. After machining to remove the sleeve, the slab size is 370mm in length, 360mm in width, 70mm in thickness, and weighs 205.4kg (the surface layer is severely damaged and needs to be removed by mechanical processing, which increases the subsequent processing steps and greatly reduces the efficiency).

[0054] Compared with the prior art, the beneficial effects of this application are: 1. The present application provides a hot forging method for tantalum-tungsten alloy, which prevents oxidation of the ingot during heating by combining glass powder and sheathing technology on the tantalum-tungsten alloy ingot. The sheathing will fall off automatically during the hot forging process. The operation is simple, the heating cost is saved, and it has a good anti-oxidation effect, which prevents the material from being oxidized at high temperature for a long time and causing the forging performance to deteriorate. The present application avoids oxidation of the ingot during the heating process before the hot forging process, and improves the product yield of the tantalum-tungsten alloy; the sheathing will fall off automatically during the hot forging process, and no further lathe processing is required after the hot forging process, which simplifies the hot forging process steps of the tantalum-tungsten alloy.

[0055] 2. The tantalum-tungsten alloy ingot in this application is obtained by electron beam melting. Due to the characteristics of its metallographic structure, the conditions required for the sheathing treatment are simple and the operation process is convenient. In addition, the tantalum-tungsten alloy obtained by the electron beam melting method is large in size and heavy in weight. After the sheathing is performed, a large-size and heavy-weight tantalum-tungsten alloy forging product can be obtained at one time. It further avoids the defects of severe burning and low material yield in the forging of small-size and small-batch tantalum-tungsten alloys. Before this application, the maximum weight of tantalum-tungsten alloy hot forging was only about 50kg. This application realizes the forging of large-size and heavy tantalum-tungsten alloys, and the implementation case is greater than 200kg, making the hot forging deformation of large-size and large-unit-weight tantalum-tungsten alloys possible.

[0056] 3. The anti-oxidation glass powder coating used in this application has stable performance and is non-toxic. It does not react with stainless steel sleeves and tantalum-tungsten alloys. It can form a barrier between the sleeve and the alloy, and has a secondary anti-oxidation protection during the heating process. It can also facilitate the spontaneous rupture and fall off of the sleeve during the hot forging process, and does not affect the reversing forging during the alloy hot forging process, which is conducive to the precise control of the shape and size of the finished forging.

[0057] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A hot forging method for tantalum-tungsten alloy, characterized in that: The following steps are involved: Hot forging the tantalum-tungsten alloy preform after keeping it warm; The tantalum-tungsten alloy preform comprises a tantalum-tungsten alloy core, glass powder and a metal sheath layer from the inside to the outside; The insulation temperature is 900°C to 1400°C; The diameter of the tantalum-tungsten alloy core is 150 mm to 300 mm.

2. The processing method according to claim 1, characterized in that: The operating temperature of the glass powder is 850°C to 1400°C.

3. The processing method according to claim 1, characterized in that: The melting point of the metal sheath layer is ≥ the insulation temperature.

4. The processing method according to claim 3, characterized in that: The metal sheath layer includes a stainless steel layer.

5. The processing method according to claim 1, characterized in that: The tantalum-tungsten alloy core is made by electron beam melting.

6. The processing method according to claim 1, characterized in that: The tantalum-tungsten alloy core is cylindrical; And / or, the length of the tantalum-tungsten alloy core is 100 mm to 500 mm; And / or, the mass of the tantalum-tungsten alloy is greater than 20 kg.

7. The processing method according to claim 1, characterized in that: The mass fraction of tungsten in the tantalum-tungsten alloy core is 2% to 15%.

8. The processing method according to claim 1, characterized in that: The thickness of the metal sheath layer is 2 mm to 10 mm.

9. The processing method according to claim 1, characterized in that: The insulation time is 0.5h~10h.

10. The processing method according to claim 1, characterized in that: The parameters of the hot forging process are as follows: The initial forging temperature is 900℃~1400℃.

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