Upsetting forging method for tungsten and tungsten alloy

Abstract

The invention discloses an upsetting forging method for tungsten and tungsten alloy, which relates to the technical field of forging, and comprises the following steps of: loading a blank into an upsetting sheath, and welding and sealing; carrying out first heat treatment on the upset blank; then upsetting and forming, wherein the deformation amount is 15-35%; carrying out secondary heat treatment on the blank subjected to upsetting forming; then upsetting and forming, wherein the deformation amount is 20%-35%; the treated blank is subjected to third-time heat treatment and then subjected to upsetting forming, and the deformation is 10%-20%; the blank continues to be subjected to fourth heat treatment and then subjected to upsetting forming, the deformation is 5%-15%, and then heat treatment and upsetting forming are repeated till a finished product is qualified; carrying out annealing heat treatment on the treated blank; and finally, the sheath is removed, and an upsetting finished product is obtained. According to the method, the sheath is additionally arranged on the tungsten and the tungsten alloy material blank, so that cracking of the tungsten and the tungsten alloy material blank caused by uneven temperature drop, atmosphere and deformation is effectively avoided, and the yield is increased.

Description

Technical Field

[0001] The invention relates to the technical field of forging, and in particular to an upsetting forging method for tungsten and its alloy. Background Art

[0002] Tungsten is a refractory transition metal with a high melting point (3410℃). It has excellent high-temperature performance and strong resistance to acid and alkali corrosion. Tungsten and its alloy products are widely used in modern microelectronics manufacturing, high-temperature protection and other fields.

[0003] Tungsten and its alloys have poor plasticity, narrow hot working range, poor plastic deformation performance, large deformation resistance, easy to crack, and special application requirements face great technical difficulties in processing. Tungsten and its alloys are typical low-temperature brittle materials due to their intrinsic characteristics such as crystal structure and interatomic bonding mode. They are difficult to process and are often produced by forging, drawing, rolling, extrusion, etc. Round tungsten and its alloy sheets are generally produced by rolling square billets, which are cut and shaped on the slabs after rolling. Tungsten and its alloys are difficult to roll and require high processing equipment. The yield rate is generally around 50%.

[0004] Heated upsetting forging is an efficient way to produce round billets, but due to the narrow hot working range of tungsten and its alloys, poor forging performance, large deformation resistance, and easy cracking, it faces great technical difficulties. The main problems are: during the upsetting process, the surface metal cracks on the side wall and the upper and lower end faces due to the rapid temperature drop and the difficulty in coordinating deformation, making it difficult to further process; only part of the end face in contact with the upper and lower anvils of the forging is restricted, and there is a difficult deformation area. The metal deformation is uneven during upsetting, and the deformation of the metal in different parts is difficult to coordinate, which is prone to stratification and cracking; the surface oxidation of the billet is serious during high-temperature processing in the air, which greatly reduces the processing yield of tungsten and its alloy billets. How to achieve high-yield upsetting forging of tungsten and its alloy billets is a problem that needs to be solved urgently by existing preparation technology. Summary of the invention

[0005] The purpose of the present invention is to coordinate the problem that tungsten and its alloys have poor plastic deformation ability, resulting in easy cracking during upsetting deformation and poor yield. The present invention relates to a method for upsetting forging of tungsten and its alloys. This method improves the temperature unevenness of the blank along the diameter direction during the upsetting forging process and improves the stress conditions of the tungsten blank during the upsetting forging process by adding a sleeve, thereby ensuring the shape of the pressed blank, avoiding cracking of the blank, and effectively improving the upsetting yield.

[0006] The technical solution of the present invention is as follows:

[0007] A method for upsetting and forging tungsten and its alloys, comprising the following steps:

[0008] S1, putting the blank into the upsetting sleeve, welding and sealing, and obtaining the upsetting blank;

[0009] S2. Load the upsetting blank into a heating furnace and keep it warm in the temperature range of 1000-1400°C. The holding time is 100 minutes for a blank with a diameter of 100 mm after the heating furnace reaches the temperature.

[0010] S3, the heat-insulated blank is subjected to upsetting, the upsetting speed is controlled at 1-5 mm / s, and the deformation amount per pass is 15% to 35%;

[0011] S4, the blank treated in S3 is loaded into a heating furnace, and kept warm in a temperature range of 1000-1400°C. The holding time is 200 minutes for a blank with a diameter of 100 mm after the heating furnace reaches the temperature;

[0012] S5, placing the blank processed in S4 into a die for upsetting, with the upsetting speed controlled at 1-5 mm / s and the deformation amount at 20% to 35%;

[0013] S6, loading the billet processed in S5 into a heating furnace, and keeping it warm in the temperature range of 1000-1400°C. The keeping time is 200 minutes for a billet with a diameter of 100 mm after the heating furnace reaches the temperature;

[0014] S7, placing the blank processed in S6 into a mold for upsetting, with a deformation amount of 10% to 20%;

[0015] S8, loading the billet processed in S7 into a heating furnace, and keeping it warm in the temperature range of 1000-1400°C, and the keeping time is 200 minutes for a billet with a diameter of 100mm after the heating furnace reaches the temperature;

[0016] S9, placing the blank processed in S8 into a mold for upsetting, with the upsetting speed controlled at 1-5 mm / s and the deformation amount at 5% to 15%; then repeating S8 and S9 until the finished product size requirements are met;

[0017] S10, loading the billet after S9 treatment into a heating furnace, and performing annealing heat treatment at a temperature of 1350°C, the holding time is carried out according to the billet diameter of 100mm being held for 200min after the heating furnace reaches the temperature, and the heating and cooling rate is 2-5°C / min;

[0018] S11, removing the sheath of the blank in S10 to obtain a roughened finished product.

[0019] As a preferred embodiment of the present invention, in step S1, the blank composition includes pure tungsten and / or W-Ni-Fe, W-Ni-Cu, W-Mo, W-Ta, W-Nb, W-ThO 2, multi-component alloy with tungsten as the main component, and the original density of the billet must be greater than 90% of its theoretical density.

[0020] As a preferred solution of the present invention, in step S1, the sheath material is iron-based metal, the side wall sheath thickness is 15-30mm, and the end cover thickness is 3-7mm. Preferably, the sheath material is 316L stainless steel, the side wall sheath thickness is 20mm, and the end cover thickness is 5mm.

[0021] As a preferred embodiment of the present invention, in steps S2, S4, S6, S8, and S10, the atmosphere of the heating furnace is air or a reducing or inert atmosphere.

[0022] As a preferred embodiment of the present invention, in steps S3, S5 and S7, the upsetting is performed on a vertical frame hydraulic press, the upper and lower anvils are flat, and the upsetting pressure applied by the hydraulic press to the end face of the blank needs to be greater than 300 MPa. Preferably, the initial upsetting height deformation is 20%-35%, and more preferably, the initial upsetting height deformation is 25%.

[0023] As a preferred solution of the present invention, each time the upsetting forging is performed, the blank needs to be rotated 180 degrees in the height direction, and the active pressure-bearing surface of the blank is opposite to the active pressure-bearing surface of the previous upsetting.

[0024] As a preferred embodiment of the present invention, in steps S2, S4, S6 and S8, the blank is loaded into the heating furnace after the temperature of the heating furnace reaches a preset temperature, and upsetting forging is performed after the insulation is completed. Preferably, the insulation temperature is 1350°C.

[0025] As a preferred embodiment of the present invention, in step S10, the temperature is lowered along with the furnace after heat preservation, and the cooling rate is 2-5°C / min.

[0026] The beneficial effects of the present invention are:

[0027] (1) The present invention adopts the method of adding a sheath to the tungsten and alloy material blank, which effectively avoids the cracking of the tungsten and alloy blank caused by temperature drop, atmosphere and uneven deformation, and improves the yield rate. The sheath material can change the overall boundary conditions of the upsetting process of the tungsten and alloy blank, and can play the role of insulation layer and anti-oxidation layer, effectively ensuring the forging temperature of the inner layer blank, avoiding the oxidation of the blank and the cracking caused by the temperature drop of the side wall; the thicker sheath side wall can reduce the aspect ratio of the blank, improve the forging performance, and control the shape of the blank. Even the blank with a large aspect ratio is not easy to bend sideways and cause the shape of the blank to be unstable; the upper and lower end bread sheaths serve as forging cushions, so that the internal tungsten and alloy blank is not directly affected by the upper and lower anvil surfaces during the upsetting process. The deformation process is that the deformation of the upper and lower end surfaces drives the internal blank to move horizontally. The shape of the blank is close to a cylinder, and the outer metal has a small tendency to bulge, which is conducive to the smooth upsetting deformation.

[0028] (2) The present invention solves the problems of low yield, surface cracking and difficult shape control of tungsten and its alloys due to forging temperature drop, air oxidation and the like by lowering the processing temperature, and this method is applicable to all kinds of billets with a height-to-diameter ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Macroscopic photograph of the finished upsetting product obtained in the manner of Example 1;

[0030] Figure 2 Microstructure photo of the upsetting product obtained in the manner of Example 1;

[0031] Figure 3 Macroscopic photograph of the upsetting product obtained in the manner of Comparative Example 1;

[0032] Figure 4 Microstructure photograph of the upsetting product obtained in the manner of Comparative Example 1. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0034] Example 1

[0035] S1. Place a 100mm Φ and 150mm high tungsten-thorium alloy (ThO 2 The blank (content is 0.25%) is loaded into a 316L stainless steel upsetting sleeve, the side wall thickness of the sleeve is 20mm, the upper and lower covers are 5mm thick, and the blank is sealed by argon arc welding. The initial density of the blank is 95% of the theoretical density;

[0036] S2. Place the upsetting blank into an air atmosphere muffle furnace and keep it at 1250° C. for 100 min.

[0037] S3, the blank after heat preservation is subjected to upsetting and forming, the equipment used is a 2500-ton vertical four-column frame hydraulic press, the upsetting speed is 4mm / s, and the deformation amount per pass is 25%;

[0038] S4. The billet forged in S3 is placed in an air atmosphere muffle furnace and kept warm at 1250°C for 200 minutes.

[0039] S5, placing the blank after the heat preservation in S4 between the upper and lower anvils for upsetting, the upsetting speed is controlled at 4 mm / s, and the deformation is 25%;

[0040] S6. Place the billet treated in S5 into an air atmosphere muffle furnace and keep it at 1250° C. for 200 min.

[0041] S7, placing the blank processed in S6 between the upper and lower anvils for upsetting, with a deformation amount of 10%;

[0042] S8. Place the blank treated in S7 into a heating furnace and keep it warm within a temperature range of 1250° C. for 200 min.

[0043] S9, placing the blank after the heat preservation in S8 into the upper and lower anvils for upsetting, the upsetting speed is controlled at 4 mm / s, and the deformation is 10%;

[0044] S10, loading the billet after S9 treatment into a heating furnace, and performing annealing heat treatment at a temperature of 1350°C. The holding time is 200 minutes for a billet with a diameter of 100 mm after the heating furnace reaches the temperature, and the heating and cooling rate is 2-5°C / min.

[0045] S11, removing the sheath from the blank obtained by the S10 treatment by turning to obtain a roughened finished product.

[0046] After testing, the surface of the upsetting product has no cracks, and the overall side wall drum trend is not obvious. The macroscopic photos are as follows: Figure 1 As shown in the figure, there are no micro cracks in the internal microstructure. The microstructure photo is shown in the figure Figure 2 shown.

[0047] Example 2

[0048] S1. Put the pure tungsten blank of Φ100mm and height 100mm into a 45 steel upsetting sleeve with a side wall thickness of 20mm and upper and lower covers of 5mm, and seal it by argon arc welding;

[0049] S2. Place the upsetting blank into an argon-protected heating furnace and keep it warm at 1250° C. for 100 min.

[0050] S3, the blank after heat preservation is subjected to upsetting and forming, the equipment used is a 1500-ton vertical four-column frame hydraulic press, the upsetting speed is 2.5 mm / s, and the deformation amount per pass is 20%;

[0051] S4. The billet forged in S3 is placed in an argon-protected heating furnace and kept warm at 1250° C. for 200 min.

[0052] S5, placing the blank after the heat preservation in S4 between the upper and lower anvils for upsetting, the upsetting speed is controlled at 2.5 mm / s, and the deformation is 20%;

[0053] S6. The blank obtained in S5 is placed in an argon-protected heating furnace and kept warm at 1250° C. for 200 min.

[0054] S7, placing the blank processed in S6 between the upper and lower anvils for upsetting, with a deformation amount of 15%;

[0055] S8. Place the blank treated in S7 into an argon-protected heating furnace and keep it warm within a temperature range of 1250° C. for 200 min.

[0056] S9, placing the blank after the heat preservation in S8 into the upper and lower anvils for upsetting, the upsetting speed is controlled at 2.5 mm / s, and the deformation is 15%;

[0057] S10. The blank treated in S9 is placed in an argon-protected heating furnace, and annealed at 1350°C for 200 min at a heating rate of 3°C / min.

[0058] S11, removing the sheath from the blank processed in S10 by turning to obtain a roughened finished product.

[0059] After testing, it was found that there were no cracks on the surface of the roughened product and no micro cracks in the internal microstructure.

[0060] Comparative Example 1

[0061] S1. Put the pure tungsten billet of Φ140mm and height 80mm into the hydrogen molybdenum wire heating furnace and keep it at 1700℃ for 120min.

[0062] S2, the blank after heat preservation is subjected to upsetting forming, the equipment used is a 750kg air forging hammer, the upsetting speed is 10mm / s, and the deformation amount per pass is 20%;

[0063] S3. The forged billet of S2 is placed in a hydrogen molybdenum wire heating furnace and kept warm at 1700°C for 120 minutes.

[0064] S4, placing the blank after the heat preservation in S3 between the upper and lower anvils for upsetting, the upsetting speed is controlled at 10 mm / s, and the deformation is 20%;

[0065] After testing, it was found that the blank had cracked severely and it was difficult to continue upsetting. The macroscopic photos are as follows: Figure 3 As shown in the figure, there are micro cracks in the internal microstructure. The microstructure photo is shown in the figure Figure 4 shown.

[0066] The above-mentioned embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for upsetting tungsten and its alloys, characterized in that: The following steps are involved: S1, putting the blank into the upsetting sleeve, welding and sealing, and obtaining the upsetting blank; S2. Load the upsetting blank into a heating furnace and keep it warm in the temperature range of 1000-1400°C. The holding time is 100 minutes for a blank with a diameter of 100 mm after the heating furnace reaches the temperature. S3, the heat-insulated blank is subjected to upsetting, the upsetting speed is controlled at 1-5 mm / s, and the deformation amount per pass is 15% to 35%; S4, the blank treated in S3 is loaded into a heating furnace, and kept warm in a temperature range of 1000-1400°C. The holding time is 200 minutes for a blank with a diameter of 100 mm after the heating furnace reaches the temperature; S5, placing the blank processed in S4 into a die for upsetting, with the upsetting speed controlled at 1-5 mm / s and the deformation amount at 20% to 35%; S6, loading the billet processed in S5 into a heating furnace, and keeping it warm in the temperature range of 1000-1400°C. The keeping time is 200 minutes for a billet with a diameter of 100 mm after the heating furnace reaches the temperature; S7, placing the blank processed in S6 into a mold for upsetting, with a deformation amount of 10% to 20%; S8, loading the billet processed in S7 into a heating furnace, and keeping it warm in the temperature range of 1000-1400°C, and the keeping time is 200 minutes for a billet with a diameter of 100mm after the heating furnace reaches the temperature; S9, placing the blank processed in S8 into a mold for upsetting, with the upsetting speed controlled at 1-5 mm / s and the deformation amount at 5% to 15%; then repeating S8 and S9 until the finished product size requirements are met; S10, loading the billet after S9 treatment into a heating furnace, and performing annealing heat treatment at a temperature of 1350°C, the holding time is carried out according to the billet diameter of 100mm being held for 200min after the heating furnace reaches the temperature, and the heating and cooling rate is 2-5°C / min; S11, removing the sheath of the blank in S10 to obtain a roughened finished product.

2. The method according to claim 1, characterized in that In step S1, the blank composition includes pure tungsten and / or W-Ni-Fe, W-Ni-Cu, W-Mo, W-Ta, W-Nb, W-ThO2, and a multi-element alloy with tungsten as the main component, and the original density of the blank must be greater than 90% of its theoretical density.

3. The method according to claim 1, characterized in that In step S1, the sheath material is iron-based metal, the side wall sheath thickness is 15-30 mm, and the end wall sheath thickness is 3-7 mm.

4. The method according to claim 1, characterized in that: In steps S2, S4, S6, S8 and S10, the atmosphere of the heating furnace is air or a reducing or inert atmosphere.

5. The method according to claim 1, characterized in that In steps S3, S5 and S7, the upsetting is performed on a vertical frame hydraulic press, the upper and lower anvils are flat, and the upsetting pressure applied by the hydraulic press to the end face of the blank needs to be greater than 300 MPa.

6. The method according to claim 1, characterized in that Each time the upsetting forging is performed, the blank needs to be rotated 180 degrees in the height direction, and the active pressure-bearing surface of the blank is opposite to the active pressure-bearing surface of the previous upsetting.

7. The method according to claim 1, characterized in that In steps S2, S4, S6 and S8, the blank is loaded into the heating furnace after the temperature of the heating furnace reaches a preset temperature, and upsetting forging is performed after the insulation is completed.

8. The method according to claim 1, characterized in that In step S10, the temperature is lowered along with the furnace after heat preservation, and the cooling rate is 2-5°C / min.

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