A forging method of high-performance high-organization-uniformity titanium alloy forging blank

Abstract

The application discloses a forging method of high-performance high-organization-uniformity titanium alloy forging blank. β The titanium alloy raw material is forged into a cuboid blank at a temperature of T (20-40) ℃, and the upper and lower surfaces of the cuboid blank are required to be square; if the ratio of the height of the cuboid blank to the length of the cross section is less than 2, the cuboid blank is subjected to pre-drawing treatment, and then is sequentially subjected to axial upsetting-drawing, radial drawing, radial upsetting-drawing, square forming, radial edge-pressing-drawing, radial edge-pressing-upsetting, square forming and axial drawing under specific forging process parameters, so that eight times of re-forging and forming forging are completed, and finally the high-performance high-organization-uniformity titanium alloy forging blank is obtained. The forging method combines eight-directional alternating upsetting-drawing with radial and axial upsetting-drawing, greatly reduces the deformation dead zone, and significantly improves the comprehensive performance of the titanium alloy forging blank, so that the high-performance requirement of titanium alloy material for special parts is met, and the application prospect of the material is improved.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal processing technology, and specifically relates to a forging method for high-performance titanium alloy forging billets with high microstructure uniformity. Background Technology

[0002] Titanium and titanium alloys possess advantages such as low density, high specific strength, low coefficient of thermal expansion, good corrosion resistance, high biocompatibility, and ease of welding, leading to their widespread application in defense, aerospace, chemical, medical, and biological fields. Particularly due to their high specific strength and excellent mechanical properties, they are widely used in parts operating in marine environments and extreme conditions. However, the low work hardening rate, high deformation resistance, high notch sensitivity, poor thermal conductivity, and low plastic shear resistance of titanium alloys significantly impact their mechanical properties. Therefore, forging is necessary to improve their microstructure.

[0003] Due to their inherent properties, titanium alloys cannot achieve grain refinement through repeated phase transformations via heat treatment. Therefore, grain refinement in titanium alloy ingots can only be improved through forging. Currently, there are two common forging methods for titanium alloys: upset drawing and reversible upset drawing. In the first type, upset drawing, the grains are only elongated and compressed along the axial direction, resulting in complete axial grain breakage. However, the grains are elongated in the transverse direction, lacking fineness and exhibiting uneven distribution, which manifests as elongated defects during flaw detection. The second type, reversible upset drawing, while adding an additional face upsetting, achieves sufficient grain breakage and eliminates elongated grains. However, flaw detection along the axial direction reveals uneven microstructure distribution. Dividing the end face into eight sections from the center point, four difficult-to-deform zones and four easily-deformable zones exist. Due to differences in stress, the degree of deformation varies, resulting in uneven microstructure distribution. In other words, the commonly used forging methods in the current technology all have deformation dead zones, resulting in uneven microstructure in different parts of the final forging, making it difficult to meet the high performance requirements of special parts.

[0004] In view of this, this invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a forging method for high-performance titanium alloy forging billets with high microstructure uniformity. This invention solves the problem that existing forging methods all have deformation dead zones, resulting in uneven microstructure in different parts of the final forging, by combining eight-directional reverse upsetting with radial and axial upsetting.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a forging method for high-performance titanium alloy forging billets with high microstructure uniformity, the forging method comprising the following steps:

[0008] Step 1: First, forge the titanium alloy raw material into a first cuboid billet. The upper and lower M faces of the first cuboid billet are required to be square. If the ratio of the height to the length of the cross-section of the first cuboid billet is less than 2, then the first cuboid billet is pre-drawn. After the pre-drawn lengthening treatment, the height h of the first cuboid billet is 2a, the length L1 and width L2 of the M face are both a, and the diagonals of the M face are K1 and K2, which are 1.4a.

[0009] Step 2: The first cuboid blank is uplifted along the axial direction to obtain the first cube blank. The height h of the first cube blank is 1.25a, ​​and the length L1 and width L2 of the M surface are also 1.25a.

[0010] Step 3: The first cube blank is drawn radially to obtain the second cuboid blank. The height h of the second cuboid blank is a, the length L1 of the M surface is 2a, and the width L2 is a.

[0011] Step 4: After the second cuboid blank is radially uptaken, a third cuboid blank is obtained. The height h of the third cuboid blank is a, the length L1 of the M surface is a, and the width L2 is 2a.

[0012] Step 5: After the third cuboid blank is squared radially for the first time, a second cube blank is obtained. The height h of the second cube blank is 1.25a, ​​and the length L1 and width L2 of the M surface are also 1.25a.

[0013] Step 6: After the second cube blank is drawn out along the radial edge, a fourth cuboid blank is obtained. The height h of the fourth cuboid blank is a. At this time, the length of the M face becomes K1, which is equal to 2a, and the width of the M face becomes K2, which is equal to a.

[0014] Step 7: After the fourth cuboid blank is radially upset, a fifth cuboid blank is obtained. The height h of the fifth cuboid blank is a, and the length K1 of the M surface is a and the width K2 is 2a.

[0015] Step 8: After the fifth cuboid blank is squared radially for the second time, a third cube blank is obtained. The height h of the third cube blank is 1.25a, ​​and the length K1 and width K2 of the M surface are also 1.25a.

[0016] Step 9: The third cubic billet is drawn along the axial direction to obtain a titanium alloy forging billet that is ultimately a cuboid. The height h of the titanium alloy forging billet is 2a, and the length K1 and width K2 of the M surface are both a.

[0017] Furthermore, the forging temperature in the forging method is T. β -(20~40)℃, holding time is 0.7~1.2 times the shortest side length of the billet, and air cooling after forging;

[0018] The unit for the shortest side length of the billet is mm, and the unit for the heat preservation time is min.

[0019] Furthermore, in the forging method, the upsetting rate is 18mm / s to 22mm / s. The upsetting should be done by using a split hammer upsetting method, and the amount of reduction of a single hammer should be ≤ 1 / 2 of the total deformation in this pass, in order to avoid overheating of the center of the titanium alloy billet and reduce the deformation dead zone of the titanium alloy billet.

[0020] Furthermore, in the forging method, the drawing rate is 28 mm / s to 32 mm / s, and the feed amount is ≤ 2 / 3 of the anvil width.

[0021] Furthermore, the titanium alloy raw material is a cuboid blank or a cylindrical blank.

[0022] Furthermore, when the titanium alloy raw material is square or round, the rectangular or cylindrical blank should first be forged into a regular square prism blank, and the ratio of the height of the regular square prism blank to the length of its cross section should be greater than or equal to 2.

[0023] Furthermore, when the titanium alloy forging billet modified by the forging method has a specification of 205mm×205mm×410mm~230mm×230mm×460mm, the forging equipment selected is a 20MN fast forging machine, the width of the upper hammer and the lower flat anvil is 450mm, the flat anvil radius is R30mm, and the length is 1200mm.

[0024] Furthermore, in the forging method, before forging the titanium alloy raw material, the jaws, upper hammer and lower anvil of the forging equipment should be preheated at a temperature of 200℃~300℃.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention provides a forging method, which first forges raw materials of different specifications into special rectangular billets (shaped like regular square prisms), requiring that the ratio of their height to the minimum side length be greater than or equal to 2; then, at 20-40°C below the phase transformation point of the titanium alloy, various upsetting and drawing methods are used to reduce the deformation dead zone. Specifically, the forging and forming process is carried out in sequence as follows: axial upsetting → radial drawing → radial upsetting → squaring → radial pressing and drawing → radial pressing and upsetting → squaring → axial drawing, for a total of up to eight forging and forming forging processes. Compared with the prior art, this method significantly reduces the deformation dead zone, resulting in sufficient fragmentation of the billet structure during the forging process, and uniform structure in different parts. The final forging (forging billet) has a uniform structure in different parts, which significantly improves the comprehensive performance of the titanium alloy forging billet, thereby meeting the high performance requirements of titanium alloy materials for special parts.

[0027] 2. The present invention provides a forging method applicable to various titanium alloy grades, such as TC4, TC11, TA15, etc., and also applicable to billets of any shape that can be forged into regular square prisms. Attached Figure Description

[0028] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of billet deformation during the forging process of the forging method of the present invention;

[0031] Figure 2 These are high and low magnification microstructures and ultrasonic flaw detection comparison images of the forged billets after modification in Example 1 of the prior art (Solution 1) and the present invention (Solution 2);

[0032] Figure 3 This is a comparison diagram of the microstructure of the forged billet after modification in the prior art (Scheme 1) and the present invention (Scheme 2) in Embodiment 2. Detailed Implementation

[0033] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0034] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] Please see Figure 1 As shown, the present invention provides a forging method for high-performance titanium alloy forging billets with high microstructure uniformity, specifically including the following steps:

[0036] Step 1: First, forge the titanium alloy raw material into a first cuboid billet. The top and bottom M faces of the first cuboid billet must be squares. If the ratio of the height of the first cuboid billet to the side length of the square is less than 2, then pre-draw the first cuboid billet. After pre-drawing, the height h of the first cuboid billet is 2a, the length L1 and width L2 of the M face are both a, and the diagonals K1 and K2 of the M face are 1.4a. See [link / description]. Figure 1 ①;

[0037] Step 2: The first cuboid blank is uplifted axially to obtain the first cube blank. The height h of the first cube blank is 1.25a, ​​and the length L1 and width L2 of the M surface are also 1.25a. See... Figure 1 ②;

[0038] Step 3: The first cubic blank is radially elongated to obtain a second cuboid blank. The height h of the second cuboid blank is a, the length L1 of surface M is 2a, and the width L2 is a. (See...) Figure 1 ③;

[0039] Step 4: The second cuboid blank is radially uplifted to obtain a third cuboid blank. The height h of the third cuboid blank is a, the length L1 of surface M is a, and the width L2 is 2a. (See...) Figure 1 ④;

[0040] Step 5: After the third cuboid blank is squared radially for the first time, a second cube blank is obtained. The height h of the second cube blank is 1.25a, ​​and the length L1 and width L2 of the M face are also 1.25a. See [link to step 5]. Figure 1 ⑤;

[0041] Step Six: After radially pressing and drawing the second cube blank, a fourth cuboid blank is obtained. The height h of the fourth cuboid blank is a. At this time, the length of face M becomes K1, where K1 equals 2a, and the width of face M becomes K2, where K2 equals a. See... Figure 1 ⑥;

[0042] Step 7: After radial upsetting of the fourth cuboid blank, a fifth cuboid blank is obtained. The height h of the fifth cuboid blank is a. At this time, the length K1 of surface M is a, and the width K2 is 2a. See Figure 1 ⑦;

[0043] Step 8: After squaring the fifth cuboid blank radially for the second time, a third cube blank is obtained. The height h of the third cube blank is 1.25a, ​​and the length K1 and width K2 of face M are also 1.25a. See [link to step 8]. Figure 1 ⑧;

[0044] Step 9: The third cubic billet is drawn axially to obtain a final rectangular titanium alloy forging billet. The height h of the titanium alloy forging billet is 2a, and the length K1 and width K2 of surface M are both a. (See...) Figure 1 9.

[0045] The titanium alloy raw material can be a cuboid billet or a cylindrical billet. When the raw material is a cuboid billet or a cylindrical billet, the cuboid billet or cylindrical billet should be forged into a regular square prism billet, and the ratio of the height of the regular square prism billet to the side length of the cross section is greater than or equal to 2.

[0046] Specifically, the heating temperature during the entire forging process is T. β -(20~40)℃, heat preservation coefficient is 0.4~1.2, heat preservation time is 0.7~1.2 times the shortest side length of the billet, and air cooling is performed after forging. The unit of the shortest side length of the billet is mm, and the unit of heat preservation time is min. The upsetting rate is 18mm / s~22mm / s, the drawing rate is 28mm / s~32mm / s, and the feed amount is ≤2 / 3 of the anvil width. In order to avoid overheating of the geometric center of the billet during the pressing process, split hammer upsetting should be used, and the single hammer pressing amount is ≤1 / 2 of the total deformation amount of this pass.

[0047] To further verify the effectiveness of the preparation method of the present invention, the inventors conducted the following specific experiments:

[0048] Example 1 (Forged into a TC4 forging billet with dimensions of 230mm×230mm×460mm)

[0049] This embodiment describes the reforging of a rectangular TC4 titanium alloy billet (230mm × 230mm × 460mm). The phase transformation point of the TC4 titanium alloy billet, measured by metallographic method, is 995℃. The forging equipment selected is a 20MN high-speed forging mill. The width of the upper hammer and lower flat anvil is 450mm, the radius of the flat anvil is R30mm, and the length is 1200mm. The specific steps are as follows:

[0050] 1) The TC4 titanium alloy billet is heated in the range of 900-960℃. When the temperature reaches 960℃, it is held for 175 minutes. The clamps, upper hammer and anvil of the equipment are preheated at a temperature of 250-300℃. Since the height of the billet is 2:1 of the minimum side length of the cross section, which meets the requirements, pre-drawing is not required.

[0051] 2) Before forging, the axial direction of the billet is vertical. The heated billet is upset along the axial direction at a rate of 20 mm / s. Full anvil upset is performed. The press down parameters are 460 mm down ↓ 370 mm down ↓ 290 mm. Upsetting is completed in two hammers. The dimensional change is: 230 mm × 230 mm × 460 mm axial upset → (290) mm × (290) mm × 290 mm; the shape is as follows Figure 1 ②

[0052] 3) The billet obtained in step 2) is rotated 90° around any radial axis (defined as radial 1) for elongation. The elongation rate is 30 mm / s, the feed amount is ≤ 2 / 3 of the anvil width, the press pressing parameters are 290 mm press ↓ 220 mm, the feed amount is 150 mm, and the elongation is completed in two hammers. Then the billet is rotated 90° around the axial axis. The press pressing parameters are (360) mm press ↓ 230 mm, the feed amount is 150 mm, and the elongation is completed in two hammers. The size change is: (290) mm × (290) mm × 290 mm radial elongation → 230 mm × (460) mm × 230 mm; the shape is as follows Figure 1 ③

[0053] 4) The billet obtained in step 3) is rotated 90° around another radial axis (defined as radial axis 2) for upsetting. The upsetting rate is 18mm / s, and the upsetting is done with a full anvil. The press down pressure parameters are 460mm down ↓ 370mm down ↓ 290mm down ↓ 230mm. The upsetting is completed in three hammer blows. Then, the billet is rotated 90° around radial axis 1 for elongation. The press down pressure parameters are 320mm down ↓ 260mm down ↓ 230mm. The elongation is completed in two hammer blows. The size change is: 230mm × (460)mm × 230mm radial upsetting → (460)mm × 230mm × 230mm; the shape is as follows. Figure 1 ④

[0054] 5) Rotate the billet obtained in step 4) 90° around the axial direction for upsetting. The upsetting rate is 22 mm / s, full anvil upsetting, and the press down pressure parameters are (460) mm down ↓ 370 mm down ↓ 280 mm. Upsetting is completed in two hammers. Rotate the billet 90° around the axial direction for shaping. The shaping upsetting rate is 20 mm / s, full anvil upsetting, and the press down pressure parameters are (290) mm down ↓ 285 mm. Then, rotate the billet 90° around the radial axis 1 for shaping. The shaping upsetting rate is 20mm / s, full anvil upsetting, and the press downsetting parameters are (295)mm down ↓ 290mm. The dimensional changes are: (460)mm × 230mm × 230mm. Square and shape → (290)mm × 290mm × 290mm. At this time, the billet direction has been restored to the original direction. Mark the axial direction. The shape is as follows: Figure 1 ⑤

[0055] 6) The billet obtained in step 5) is reheated in the furnace. The heating regime is as follows: hot material is returned to the furnace and the temperature is held for 120 minutes when it reaches 955℃. Then the billet is rotated 90° with radial 1 as the axis and then rotated 45° with axial as the axis for elongation (the pressed edge is defined as radial edge 1, and the other edge is defined as radial edge 2). The elongation rate is 28mm / s, the feed amount is ≤2 / 3 of the anvil width, the press pressing parameters are 410mm press ↓ 300mm press ↓ 220mm, the feed amount is 150mm, and the elongation is completed in four hammers. Rotate 90° with radial edge 2 as the axis (defined as radial edge 2), the press pressing parameters are (300)mm press ↓ 230mm, the feed amount is 150mm, and the elongation is completed in two hammers. The size change is: (290)mm×290mm×290mm radial pressing edge elongation → 230mm×(460)mm×230mm; the shape is as follows Figure 1 ⑥

[0056] 7) The billet obtained in step 6) is rotated 90° around the radial edge 1 as the axis for upsetting. The upsetting rate is 20mm / s, and the upsetting is done with a full anvil. The press down pressure parameters are 460mm down ↓ 370mm down ↓ 290mm down ↓ 230mm. The upsetting is completed in three hammer blows. Then, the billet is rotated 90° around the radial edge 1 as the axis for elongation. The press down pressure parameters are 320mm down ↓ 260mm down ↓ 230mm. The elongation is completed in two hammer blows. The size change is: 230mm × (460)mm × 230mm radial upsetting → (460)mm × 230mm × 230mm; the shape is as follows. Figure 1 ⑦

[0057] 8) Rotate the billet obtained in step 7 by 90° around the radial edge 2 as the axis for upsetting. The upsetting rate is 21mm / s, full anvil upsetting, and the press down pressure parameters are (460)mm down ↓370mm down ↓280mm. Upsetting is completed in two hammers. Rotate the billet by 90° around the axial axis for shaping. The shaping upsetting rate is 20mm / s, full anvil upsetting, and the press down pressure parameters are (290)mm down ↓285mm. Then rotate the billet by 90° around the radial edge 1 as the axis for shaping. The shaping upsetting rate is 20mm / s, full anvil upsetting, and the press down pressure parameters are (295)mm down ↓290mm. The size change is: (460)mm×230mm×230mm square, shaping → (290)mm×290mm×290mm. At this time, the axial direction of the billet has returned to the original axial direction; the shape is as follows. Figure 1 ⑧

[0058] 9) The billet obtained in step 8) is rotated 90° around the radial ridge 2 and drawn out at a rate of 32 mm / s. The feed rate is ≤ 2 / 3 of the anvil width. The press parameters are 290 mm ↓ 220 mm and the feed rate is 150 mm. The drawing is completed in two hammers. Then the billet is rotated 90° around the axial direction and drawn out at a rate of 30 mm / s. The feed rate is ≤ 2 / 3 of the anvil width. The press parameters are (360) mm. Press 280mm, press 230mm, feed amount is 150mm, complete the elongation in four hammers, then rotate the billet 90° around the radial ridge 1 as the axis for upsetting, upsetting rate is 20mm / s, full anvil upsetting, press down parameters are (460)mm press 260mm, the size change is: (290)mm×290mm×290mm radial elongation → 230mm×230mm×460mm, shape is as follows Figure 1 ⑨, that is, to obtain the target forging billet.

[0059] Effect verification:

[0060] Using the same ingot and the same firing process, two forging methods (see Table 1 below) were used for billet preparation, forming, taking high and low magnification samples, peeling, ultrasonic testing, and room temperature tensile property testing. Finally, the high and low magnification microstructure of the product was observed, and the ultrasonic test results and room temperature tensile property test results were compared.

[0061] Table 1 Forging methods

[0062] plan(#) Process content 1 (Prior Art) Ordinary axial upsetting + rolling forming 2 (This invention) Pulling and rolling forming

[0063] Analysis of high and low magnification tissue and ultrasound examination results:

[0064] via T β Heating to -(20~40)℃, both forging processes produced low-magnification microstructures free of metallurgical defects such as inclusions, delamination, and fine-grained bright bands, while the high-magnification microstructures were normal α+β dual-phase structures. Ultrasonic testing is a non-destructive testing method for assessing the uniformity of the internal structure and determining defects in billets. Figure 2 As can be seen, based on the defect reflection signal intensity of 0.8dB, the outer circle of the product formed by the existing technology (ordinary upsetting + rolling) has a single-point defect of 0.8+1dB, and the end face noise is higher than 50% of the 0.8dB reflection signal height, so it cannot be judged. However, the billet formed by the forging of this invention (upsetting + rolling) has a reflection signal of more than 0.8dB on the outer circle and end face, indicating that the billet has good overall uniformity and complete grain breakage.

[0065] Performance comparison:

[0066] The tensile strength of the product obtained by using the billet made by the present invention is slightly lower than that of ordinary upsetting. This is because the billet is completely broken after forging by the present invention, with no large dislocations, which leads to a decrease in tensile strength. The billet grains are finer and the plasticity is improved. On the other hand, the performance difference between the two samples of the billet forged by the present invention is small and the performance stability is good, which also reflects that the overall uniformity of the billet is better than that of ordinary upsetting. Specific parameters are shown in Table 2 below.

[0067] Table 2 Comparison of room temperature tensile properties

[0068]

[0069] Example 2 (Forged into a TC11 forging billet with dimensions of 205mm×205mm×410mm)

[0070] This embodiment describes the reforging of a cylindrical TC11 titanium alloy billet (Φ300mm×250mm). The phase transformation point of the TC11 titanium alloy billet, measured by metallographic method, is 1005℃. The forging equipment selected is a 20MN high-speed forging mill. The width of the upper hammer and lower flat anvil is 450mm, the flat anvil radius is R30mm, and the length is 1200mm. The specific steps are as follows:

[0071] 1) The TC11 titanium alloy billet is heated in the range of 900-970℃. When the temperature reaches 970℃, it is held for 190 minutes. The clamps, upper hammer and anvil of the equipment are preheated at a temperature of 200-260℃. Since the height-to-length (diameter) ratio of the billet is less than 2, it does not meet the requirements. Therefore, pre-drawing is required.

[0072] 2) Pre-drawing is performed. Before forging, the axial direction of the billet is vertical. The heated billet is drawn by rotating 90° around any radial direction (defined as radial 1). The drawing rate is 29mm / s, the feed amount is ≤2 / 3 of the anvil width, the press pressing parameters are 300mm pressing ↓200mm, the feed amount is 150mm, and the drawing is completed in two hammers. Then the billet is rotated 90° around the axial direction. The press pressing parameters are (350)mm pressing ↓270mm pressing ↓205mm, the feed amount is 150mm, and the drawing is completed in two hammers. The size change is: Φ300×250mm axial drawing → 205mm×(205)mm×410mm; the shape is as follows Figure 1 ①

[0073] 3) The billet obtained in step 2) is rotated 90° about radial axis 1 for upsetting. The upsetting rate is 18mm / s, full anvil upsetting is performed, and the press down pressure parameters are 410mm down ↓ 330mm down ↓ 260mm. Upsetting is completed in two hammers. The size change is: 205mm×(205)mm×410mm axial upsetting →(260)mm×(260)mm×260mm; the shape is as follows Figure 1 ②

[0074] 4) The billet obtained in step 3) is rotated 90° about radial axis 1 and drawn out at a rate of 31 mm / s. The feed rate is ≤ 2 / 3 of the anvil width. The press parameters are 260 mm press ↓ 195 mm and feed rate is 150 mm. The drawing is completed in two hammers. Then the billet is rotated 90° about axial axis. The press parameters are (350) mm press ↓ 205 mm and feed rate is 150 mm. The drawing is completed in two hammers. The size change is: (260) mm × (260) mm × 260 mm radial drawing → 205 mm × (410) mm × 205 mm; the shape is as follows. Figure 1 ③

[0075] 5) Rotate the billet obtained in step 4) 90° around another radial axis (defined as radial axis 2) for upsetting. The upsetting rate is 20mm / s, full anvil upsetting, and the press down pressure parameters are 410mm down ↓ 340mm down ↓ 270mm down ↓ 205mm. Upsetting is completed in three hammer blows. Then rotate the billet 90° around radial axis 1 for elongation. The press down pressure parameters are 290mm down ↓ 240mm down ↓ 205mm. Elongation is completed in two hammer blows. The size change is: 205mm × (410)mm × 205mm radial upsetting → (410)mm × 205mm × 205mm; the shape is as follows Figure 1 ④

[0076] 6) Rotate the billet obtained in step 5) 90° around the axial direction for upsetting. The upsetting rate is 22 mm / s, full anvil upsetting, and the press down pressure parameters are (410) mm down ↓ 330 mm down ↓ 250 mm down ↓ 195 mm. Upsetting is completed in three hammer blows. Rotate the billet 90° around the axial direction for shaping. The shaping upsetting rate is 20 mm / s, full anvil upsetting, and the press down pressure parameters are (300) mm down ↓ 25 mm. 5mm, then rotate the billet 90° around the radial axis 1 for shaping. The shaping upsetting rate is 20mm / s, full anvil upsetting, and the press downsetting parameters are (350)mm press↓260mm. The size change is: (410)mm×205mm×205mm square, shaping → (260)mm×260mm×260mm. At this time, the billet direction has returned to the original direction, and the axial direction is marked; the shape is as follows Figure 1 ⑤

[0077] 7) The billet obtained in step 6) is reheated in the furnace. The heating regime is as follows: hot material is returned to the furnace and the temperature is held for 110 minutes when it reaches 965℃. Then the billet is rotated 90° with radial 1 as the axis and then rotated 45° with axial as the axis for elongation (the pressed edge is defined as radial edge 1, and the other edge is defined as radial edge 2). The elongation rate is 30mm / s, the feed amount is ≤2 / 3 of the anvil width, the press pressing parameters are 370mm press ↓ 270mm press ↓ 195mm, the feed amount is 150mm, and the elongation is completed in four hammers. The billet is rotated 90° with radial edge 2 as the axis (defined as radial edge 2). The press pressing parameters are (270)mm press ↓ 230mm, the feed amount is 150mm, and the elongation is completed in two hammers. The size change is: (260)mm×260mm×260mm radial pressing edge elongation → 205mm×(410)mm×205mm; the shape is as follows. Figure 1 ⑥

[0078] 8) The billet obtained in step 7 is rotated 90° around the radial edge 1 as the axis for upsetting. The upsetting rate is 19mm / s, and the upsetting is done with a full anvil. The press down pressure parameters are 410mm down ↓ 340mm down ↓ 270mm down ↓ 205mm. Upsetting is completed in three hammer blows. Then, the billet is rotated 90° around the radial edge 1 as the axis for elongation. The press down pressure parameters are 290mm down ↓ 240mm down ↓ 205mm. Elongation is completed in two hammer blows. The size change is: 205mm × (410)mm × 205mm radial upsetting → (410)mm × 205mm × 205mm; the shape is as follows. Figure 1 ⑦

[0079] 9) The billet obtained in step 9) is rotated 90° around the radial ridge 2 as the axis for upsetting. The upsetting rate is 20mm / s, full anvil upsetting, and the press down pressure parameters are (410)mm down ↓ 330mm down ↓ 250mm down ↓ 195mm. Upsetting is completed in three hammer blows. Then, the billet is rotated 90° around the axial axis for shaping. The shaping upsetting rate is 20mm / s, full anvil upsetting, and the press down pressure parameters are (260)mm down. ↓255mm, then rotate the billet radial edge 1 90° for shaping, the shaping upsetting rate is 20mm / s, full anvil upsetting, the press pressing parameters are (265)mm pressing ↓260mm, the size change is: (410)mm×205mm×205mm square, shaping → (260)mm×260mm×260mm, at this time the axial direction of the billet has returned to the original axial direction; the shape is as follows Figure 1 ⑧

[0080] 10) The billet obtained in step 9) is rotated 90° around the radial ridge 2 and drawn out at a rate of 30 mm / s. The feed rate is ≤ 2 / 3 of the anvil width. The press parameters are 260 mm press down 195 mm and a feed rate of 150 mm. The drawing is completed in two hammers. Then the billet is rotated 90° around the axial direction and drawn out at a rate of 30 mm / s. The feed rate is ≤ 2 / 3 of the anvil width. The press parameters are (330) m. m pressure ↓ 250mm pressure ↓ 205mm, feed amount is 150mm, elongation is completed in four hammers, then the billet is rotated 90° around the radial ridge 1 as the axis for upsetting, upsetting rate is 20mm / s, full anvil upsetting, press down pressure parameters are (410)mm pressure ↓ 410mm, size change is: (260)mm×260mm×260mm radial elongation → 205mm×205mm×410mm, shape is as follows Figure 1 ⑨, that is, to obtain the target forging billet.

[0081] Effect verification:

[0082] Using the same ingot and the same firing process, two forging methods (see Table 3 below) were used to prepare the billet, form it, take high and low magnification samples, and conduct room temperature tensile tests. Finally, the high and low magnification microstructure of the product was observed and the room temperature tensile test results were compared.

[0083] Table 3 Forging Methods

[0084] plan(#) Process content 1 (Prior Art) Ordinary axial upsetting + rolling forming 2 (This invention) This invention combines jacking and rolling molding.

[0085] Comparison of high and low magnification tissues:

[0086] via T β Heating at -(20~40)℃, the low-magnification microstructures of both forging processes are free of metallurgical defects such as inclusions, delamination, and fine grain bright bands, while the high-magnification microstructure is a normal α+β dual-phase microstructure.

[0087] Performance comparison:

[0088] The tensile strength of the product obtained by using the billet made by the present invention is slightly lower than that of ordinary upsetting. This is because the billet is completely broken after forging by the present invention, with no large dislocations, resulting in a decrease in tensile strength. The billet grains are finer, and the plasticity is improved. On the other hand, the performance deviation of the two samples of the billet forged by the present invention is small, and the performance stability is good, which also reflects that the overall uniformity of the billet is better than that of ordinary upsetting. Specific parameters are shown in Table 4 below.

[0089] Table 4 Comparison of room temperature tensile properties

[0090]

[0091] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0092] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A forging method for a high-performance titanium alloy forging billet with high microstructure uniformity, characterized in that, The forging method includes the following steps: Step 1: First, forge the titanium alloy raw material into a first cuboid billet. The upper and lower M faces of the first cuboid billet are required to be square. If the ratio of the height to the length of the cross-section of the first cuboid billet is less than 2, then the first cuboid billet is pre-drawn. After the pre-drawn lengthening treatment, the height h of the first cuboid billet is 2a, the length L1 and width L2 of the M face are both a, and the diagonals of the M face are K1 and K2, which are 1.4a. Step 2: The first cuboid blank is uplifted along the axial direction to obtain the first cube blank. The height h of the first cube blank is 1.25a, ​​and the length L1 and width L2 of the M surface are also 1.25a. Step 3: The first cube blank is drawn radially to obtain the second cuboid blank. The height h of the second cuboid blank is a, the length L1 of the M surface is 2a, and the width L2 is a. Step 4: After the second cuboid blank is radially uptaken, a third cuboid blank is obtained. The height h of the third cuboid blank is a, the length L1 of the M surface is a, and the width L2 is 2a. Step 5: After the third cuboid blank is squared radially for the first time, a second cube blank is obtained. The height h of the second cube blank is 1.25a, ​​and the length L1 and width L2 of the M surface are also 1.25a. Step 6: After the second cube blank is drawn out along the radial edge, a fourth cuboid blank is obtained. The height h of the fourth cuboid blank is a. At this time, the length of the M face becomes K1, which is equal to 2a, and the width of the M face becomes K2, which is equal to a. Step 7: Upset the fourth cuboid blank radially to obtain the fifth cuboid blank. The height h of the fifth cuboid blank is a, and the length K1 of the M surface is a and the width K2 is 2a. Step 8: After the fifth cuboid blank is squared radially for the second time, a third cube blank is obtained. The height h of the third cube blank is 1.25a, ​​and the length K1 and width K2 of the M surface are also 1.25a. Step 9: The third cubic billet is drawn along the axial direction to obtain a titanium alloy forging billet that is ultimately a cuboid. The height h of the titanium alloy forging billet is 2a, and the length K1 and width K2 of the M surface are both a.

2. The forging method for high-performance titanium alloy forging billets with high microstructure uniformity according to claim 1, characterized in that, The forging temperature in the forging method is T. β - (20~40)℃, holding time is 0.7~1.2 times the shortest side length of the billet, and air cooling after forging; The unit for the shortest side length of the billet is mm, and the unit for the heat preservation time is min.

3. The forging method for high-performance, high-uniformity titanium alloy forgings according to claim 1, characterized in that, In the forging method, the upsetting rate is 18mm / s to 22mm / s. The upsetting should be done by using a split hammer upsetting method, and the amount of reduction of a single hammer should be ≤ 1 / 2 of the total deformation in this pass, in order to avoid overheating of the center of the titanium alloy billet and reduce the deformation dead zone of the titanium alloy billet.

4. The forging method for high-performance, high-uniformity titanium alloy forging billets according to claim 1, characterized in that, In the forging method, the drawing rate is 28 mm / s to 32 mm / s, and the feed amount is ≤ 2 / 3 of the anvil width.

5. The forging method for high-performance, high-uniformity titanium alloy forgings according to claim 1, characterized in that, The titanium alloy raw material is a rectangular blank or a cylindrical blank.

6. The forging method for high-performance, high-uniformity titanium alloy forgings according to claim 5, characterized in that, When the titanium alloy raw material is square or round, the rectangular or cylindrical blank should first be forged into a regular square prism blank, and the ratio of the height of the regular square prism blank to the length of its cross section should be greater than or equal to 2.

7. The forging method for high-performance, high-uniformity titanium alloy forgings according to any one of claims 1 to 6, characterized in that, When the titanium alloy forging billet modified by the forging method has a specification of 205mm×205mm×410mm~230mm×230mm×460mm, the forging equipment selected is a 20MN fast forging machine, the width of the upper hammer and the lower flat anvil is 450mm, the flat anvil radius is R30mm, and the length is 1200mm.

8. The forging method for high-performance titanium alloy forging billets with high microstructure uniformity according to claim 7, characterized in that, Before forging the titanium alloy raw material in the forging method, the jaws, upper hammer and lower anvil of the forging equipment should be preheated at a temperature of 200℃~300℃.

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