A method of upsetting tungsten and its alloys

Abstract

The application discloses a method for upsetting forging of tungsten and its alloy, and relates to the field of forging technology, which comprises the following steps: loading a blank into an upsetting sleeve and welding and sealing; first heat treatment of the upsetting blank; then upsetting forming with a deformation of 15-35%; second heat treatment of the blank after the upsetting forming; then upsetting forming with a deformation of 20-35%; third heat treatment of the treated blank, then upsetting forming with a deformation of 10-20%; fourth heat treatment of the blank, then upsetting forming with a deformation of 5-15%, and then repeating the heat treatment and the upsetting forming until the finished product is qualified; annealing heat treatment of the treated blank; and finally removing the sleeve to obtain the upsetting finished product; the blank of tungsten and its alloy is loaded into the sleeve, so that the cracking of the blank of tungsten and its alloy caused by temperature drop, atmosphere and uneven deformation is effectively avoided, and the yield of the finished product is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of forging technology, in particular to a method for upsetting forging of tungsten and its alloy. BACKGROUND

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

[0003] Tungsten and its alloy have poor plasticity, narrow hot working range, poor plastic deformation performance, large deformation resistance, and are prone to cracking. Special application requirements face great technical difficulties in processing. Due to the intrinsic characteristics such as crystal structure and atomic bonding mode, tungsten and its alloy are typical low-temperature brittle materials, which are difficult to process. Tungsten and its alloy materials are usually produced by forging, drawing, rolling, and extrusion. Circular tungsten and its alloy sheet is generally produced by rolling square billets, and cutting and shaping on the plate blank after rolling. The tungsten and its alloy material has great rolling processing difficulty, high processing equipment requirement, and poor yield, generally about 50%.

[0004] Heating upsetting forging is an efficient way to produce circular billets. However, due to the narrow hot working range of tungsten and its alloy, poor forging performance, large deformation resistance, and easy cracking, great technical difficulties are faced. The main problems are: in the upsetting process, the surface metal is difficult to coordinate due to rapid temperature drop and deformation, which leads to side wall cracking and upper and lower end surface cracking, making it difficult to further process; only part of the surface of the end surface in contact with the upper and lower anvil is restricted, there is a difficult deformation area, the metal deforms unevenly during upsetting, and the metal deformation at different positions is difficult to coordinate, which is easy to produce delamination cracking; the surface of the billet is severely oxidized during high-temperature processing in air, which greatly reduces the processing yield of tungsten and its alloy billets. How to realize high-yield upsetting forging of tungsten and its alloy billets is a problem to be solved in existing preparation technology. SUMMARY

[0005] The present application is proposed to coordinate the poor plastic deformation ability of tungsten and its alloy, which leads to easy cracking during upsetting and poor yield. A method for upsetting forging of tungsten and its alloy is provided. The method improves the temperature non-uniformity of the billet along the diameter direction during upsetting forging and improves the stress condition of the tungsten billet during upsetting forging, so as to ensure the shape of the pressed billet, avoid billet cracking, and effectively improve the upsetting yield.

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

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

[0008] S1, the blank is loaded into a upsetting sleeve, welded and sealed, and a upsetting blank is obtained;

[0009] S2, the upsetting blank is loaded into a heating furnace, and heat preservation is performed at a temperature in a range from 1000 to 1400 DEG C. The heat preservation time is 100 min according to the diameter of 100 mm of the blank after the heating furnace is heated to the temperature;

[0010] S3, the blank after heat preservation is subjected to upsetting forming, and the upsetting speed is controlled to be 1-5 mm / s, and the pass deformation is 15% to 35%;

[0011] S4, the blank after S3 treatment is loaded into a heating furnace, and heat preservation is performed at a temperature in a range from 1000 to 1400 DEG C. The heat preservation time is 200 min according to the diameter of 100 mm of the blank after the heating furnace is heated to the temperature;

[0012] S5, the blank after S4 treatment is placed into a die for upsetting forming, and the upsetting speed is controlled to be 1-5 mm / s, and the deformation is 20% to 35%;

[0013] S6, the blank after S5 treatment is loaded into a heating furnace, and heat preservation is performed at a temperature in a range from 1000 to 1400 DEG C. The heat preservation time is 200 min according to the diameter of 100 mm of the blank after the heating furnace is heated to the temperature;

[0014] S7, the blank after S6 treatment is placed into a die for upsetting forming, and the deformation is 10% to 20%;

[0015] S8, the blank after S7 treatment is loaded into a heating furnace, and heat preservation is performed at a temperature in a range from 1000 to 1400 DEG C. The heat preservation time is 200 min according to the diameter of 100 mm of the blank after the heating furnace is heated to the temperature;

[0016] S9, the blank after S8 treatment is placed into a die for upsetting forming, and the upsetting speed is controlled to be 1-5 mm / s, and the deformation is 5% to 15%. Then, S8 and S9 are repeated until the finished product size requirement is reached;

[0017] S10, the blank after S9 treatment is loaded into a heating furnace, and annealing heat treatment is performed at a temperature of 1350 DEG C. The heat preservation time is 200 min according to the diameter of 100 mm of the blank after the heating furnace is heated to the temperature, and the temperature rising and falling rate is 2-5 DEG C / min;

[0018] S11, the blank is removed from the sleeve, and a upsetting finished product is obtained.

[0019] As a preferred scheme of the present application, in step S1, the blank ingredient comprises pure tungsten and / or W-Ni-Fe, W-Ni-Cu, W-Mo, W-Ta, W-Nb, W-ThO2, and a multi-component alloy with tungsten as the main component, and the original density of the blank needs to be greater than 90% of the theoretical density.

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

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

[0022] As a preferred scheme of the present application, 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 on the end face of the blank needs to be greater than 300 MPa. Preferably, the height deformation of the initial upsetting is 20%-35%, and more preferably, the height deformation of the initial upsetting is 25%.

[0023] As a preferred scheme of the present application, the blank needs to be rotated by 180 degrees along the height direction during each upsetting forging, 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 scheme of the present application, in steps S2, S4, S6 and S8, the blank is loaded into the heating furnace after the temperature of the heating furnace reaches the preset temperature, and the upsetting forging is performed after the heat preservation is completed. Preferably, the heat preservation temperature is 1350℃.

[0025] As a preferred scheme of the present application, in step S10, the blank is cooled in the furnace after the heat preservation, and the cooling rate is 2-5℃ / min.

[0026] The present application has the following beneficial effects:

[0027] (1) The present application adopts a sheath installed on the tungsten and alloy blank, which effectively avoids the cracking of tungsten and alloy blank due to temperature drop, atmosphere and uneven deformation, and improves the yield. The sheath material can change the overall boundary conditions of the tungsten and alloy blank during the upsetting process, and can play the role of heat preservation layer and oxidation prevention layer, effectively ensuring the forging temperature of the inner blank, avoiding the oxidation of the blank and the cracking caused by the temperature drop of the side wall; the thick sheath side wall can reduce the height-diameter ratio of the blank, improve the forging performance, control the shape of the blank, and even the large height-diameter ratio blank is not easy to produce side bending and lead to instability of the blank shape; the upper and lower end face sheath acts as a soft pad for forging, so that the internal tungsten and alloy blank is not directly affected by the upper and lower anvil during the upsetting process, and the deformation process is driven by the deformation of the upper and lower end face to make the internal blank move horizontally, the shape of the blank is close to a cylinder, and the drum-shaped tendency of the outer metal is small, which is helpful for the smooth upsetting deformation.

[0028] (2) The present application solves the problems of low yield, surface cracking of blank and difficult to control shape of tungsten and alloy caused by forging temperature drop, air oxidation and other reasons by reducing the processing temperature, and this method is suitable for various height-diameter ratio blanks. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

[0033] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application. If the specific technology or condition is not specified in the embodiments, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0034] Example 1

[0035] S1, a tungsten-thorium alloy (ThO2 content is 0.25%) blank with a diameter of 100 mm and a height of 150 mm is put into a 316L stainless steel upsetting sheath, the sheath side wall thickness is 20 mm, the upper and lower cover thickness is 5 mm, it is sealed by argon arc welding, and the initial density of the blank is 95% of the theoretical density;

[0036] S2, the upsetting blank is loaded into an air atmosphere muffle furnace, and is kept at 1250°C for 100 min.

[0037] S3, the blank after the keeping is formed by upsetting, and the equipment used is a 2500-ton vertical four-column frame type oil press, the upsetting speed is 4 mm / s, and the pass deformation is 25%;

[0038] S4, the blank after the forging of S3 is loaded into an air atmosphere muffle furnace, and is kept at 1250°C for 200 min.

[0039] S5, the blank after the keeping of S4 is placed between upper and lower anvils for upsetting forming, the upsetting speed is controlled to be 4 mm / s, and the deformation is 25%;

[0040] S6, the blank after the treatment of S5 is loaded into an air atmosphere muffle furnace, and is kept at 1250°C for 200 min.

[0041] S7, the blank after the treatment of S6 is placed between upper and lower anvils for upsetting forming, and the deformation is 10%;

[0042] S8, the blank after the treatment of S7 is loaded into a heating furnace, and is kept at a temperature range of 1250°C for 200 min.

[0043] S9, the blank after the keeping of S8 is placed between upper and lower anvils for upsetting forming, the upsetting speed is controlled to be 4 mm / s, and the deformation is 10%;

[0044] S10, the blank after the treatment of S9 is loaded into a heating furnace, and is annealed at a temperature of 1350°C, the keeping time is 200 min according to the diameter of 100 mm of the blank after the heating furnace is heated, and the heating and cooling rates are 2-5°C / min.

[0045] S11, the blank after the treatment of S10 is removed from the sleeve in a turning manner to obtain an upsetting finished product.

[0046] It is detected that the upsetting finished product has no cracks on the surface, the overall sidewall has no obvious bulging trend, the macroscopic photograph is as shown in Figure 1 , and the internal microstructure also has no microcracks, and the microstructure photograph is as shown in Figure 2 .

[0047] Example 2

[0048] S1, a pure tungsten blank with a diameter of 100 mm and a height of 100 mm is loaded into a 45 steel upsetting sleeve, the sleeve sidewall thickness is 20 mm, the upper and lower cover thicknesses are 5 mm, and the sealing is welded by argon arc welding;

[0049] S2, the upsetting blank is loaded into the argon protection heating furnace, and is kept at 1250℃ for 100 min.

[0050] S3, the blank after the keeping is formed by upsetting, the used equipment is a 1500-ton vertical four-column frame type oil press, the upsetting speed is 2.5 mm / s, and the pass deformation is 20%;

[0051] S4, the blank after the forging in S3 is loaded into the argon protection heating furnace, and is kept at 1250℃ for 200 min.

[0052] S5, the blank after the keeping in S4 is placed between the upper and lower anvils to be formed by upsetting, the upsetting speed is controlled to be 2.5 mm / s, and the deformation is 20%;

[0053] S6, the blank obtained through S5 is loaded into the argon protection heating furnace, and is kept at 1250℃ for 200 min.

[0054] S7, the blank after the treatment in S6 is placed between the upper and lower anvils to be formed by upsetting, and the deformation is 15%;

[0055] S8, the blank after the treatment in S7 is loaded into the argon protection heating furnace, and is kept at 1250℃ for 200 min.

[0056] S9, the blank after the keeping in S8 is placed between the upper and lower anvils to be formed by upsetting, the upsetting speed is controlled to be 2.5 mm / s, and the deformation is 15%;

[0057] S10, the blank after the treatment in S9 is loaded into the argon protection heating furnace, and is annealed at 1350℃ for 200 min, and the heating and cooling rates are 3℃ / min.

[0058] S11, the blank after the treatment in S10 is removed from the sleeve in a turning mode, and the upsetting finished product is obtained.

[0059] Through detection, the obtained upsetting finished product is free of cracks on the surface, and is also free of micro-cracks in the internal microstructure.

[0060] Comparative Example 1

[0061] S1, a pure tungsten blank with a diameter of 140 mm and a height of 80 mm is loaded into a hydrogen molybdenum wire heating furnace, and is kept at 1700℃ for 120 min.

[0062] S2, the blank after the keeping is formed by upsetting, the used equipment is a 750 kg air hammer, the upsetting speed is 10 mm / s, and the pass deformation is 20%;

[0063] S3, the blank after forging in S2 is put into a hydrogen molybdenum wire heating furnace, and is kept at 1700℃ for 120 minutes.

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

[0065] It is detected that the blank has been seriously cracked at this time, the upsetting is difficult to continue, the macroscopic photo is as shown in Figure 3 , and the internal microstructure has micro-cracks, the microstructure photo is as shown in Figure 4 .

[0066] The above-described embodiments only express the preferred embodiments of the present application, the description is more specific and detailed, but it should not be understood as the limitation of the patent scope of the present application. It should be pointed out that for the ordinary skilled in the art, according to the above-described technical solutions and concepts, other various corresponding changes and deformations can also be made, and all these changes and deformations should belong to the protection scope of the claims of the present application.

Claims

1. A method of upsetting forging tungsten and its alloys, characterized by, It comprises the following steps: S1, put the blank into the upsetting sleeve, weld and seal, and obtain the upsetting blank; S2, put the upsetting blank into the heating furnace, and heat at 1000-1400℃, and the holding time is 100min when the diameter of the blank is 100mm; S3, upset the blank after holding, and the upsetting speed is controlled at 1-5mm / s, and the pass deformation is 15%-35%; S4, put the blank after S3 into the heating furnace, and heat at 1000-1400℃, and the holding time is 200min when the diameter of the blank is 100mm; S5, put the blank after S4 into the mold for upsetting, and the upsetting speed is controlled at 1-5mm / s, and the deformation is 20%-35%; S6, put the blank after S5 into the heating furnace, and heat at 1000-1400℃, and the holding time is 200min when the diameter of the blank is 100mm; S7, put the blank after S6 into the mold for upsetting, and the deformation is 10%-20%; S8, put the blank after S7 into the heating furnace, and heat at 1000-1400℃, and the holding time is 200min when the diameter of the blank is 100mm; S9, put the blank after S8 into the mold for upsetting, and the upsetting speed is controlled at 1-5mm / s, and the deformation is 5%-15%; then repeat S8 and S9 until the finished product size requirement is reached; S10, put the blank after S9 into the heating furnace, and anneal at 1350℃, and the holding time is 200min when the diameter of the blank is 100mm, and the heating and cooling rate is 2-5℃ / min; S11, remove the blank sleeve of S10, and obtain the upsetting finished product.

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

3. The method of claim 1, wherein, In step S1, the sleeve material is iron-based metal, the side wall sleeve thickness is 15-30mm, and the end face sleeve thickness is 3-7mm.

4. The method of claim 1, wherein, In steps S2, S4, S6, S8, S10, the atmosphere of the heating furnace is air or reducing and inert atmosphere.

5. The method of claim 1, wherein, In steps S3, S5, S7, the upsetting is carried out on a vertical frame hydraulic machine, the upper and lower anvil is flat, and the upsetting pressure applied by the hydraulic machine on the blank end face needs to be greater than 300mpa.

6. The method of claim 1, wherein, The blank needs to be rotated by 180 degrees along the height direction each time the upsetting forging is carried out, and the driven pressure bearing surface of the blank is opposite to that of the previous pass.

7. The method of claim 1, wherein, In steps S2, S4, S6, S8, the blank is put into the heating furnace after the temperature of the heating furnace reaches the preset temperature, and the upsetting forging is carried out after holding.

8. The method of claim 1, wherein, In step S10, the furnace is cooled after holding, and the cooling rate is 2-5℃ / min.

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