A forging method for improving the uniformity of titanium material

Abstract

This invention discloses a forging method for improving the uniformity of titanium microstructure. The method includes: 1. performing axial upsetting deformation on the original titanium ingot at 1150℃, followed by heat treatment in the furnace and side upsetting diagonal drawing; 2. At the phase transformation point T... β The above involves multiple upsetting processes; thirdly, at the phase transition point T... β After heat treatment, it is water-cooled; fourth, at the phase transition point T β The following steps involve multiple upsetting and drawing processes; 5. At the phase transition point T β The forming and forging process is carried out under these conditions. This invention employs a "large upsetting + remelting + side upsetting and diagonal drawing" upsetting deformation method to gradually break up and refine the cast grains, significantly improving the grain breaking effect. It achieves alternating deformation between difficult and easy deformation zones, ultimately efficiently obtaining titanium materials with uniform microstructure, significantly reducing material processing costs. It is applicable to the forging of conventional two-phase titanium alloys such as TC4 and TC11, as well as near-α type titanium alloys such as process-pure titanium, TA18, and TA22.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy material processing technology, specifically relating to a forging method for improving the uniformity of titanium material structure. Background Technology

[0002] Titanium and titanium alloys possess advantages such as high specific strength, heat resistance, and corrosion resistance, and are widely used in aerospace, marine, and petrochemical industries. With the evolving equipment needs of these fields, the application of titanium alloys is trending towards larger sizes, lower costs, and higher homogeneity. The hot working process of titanium alloys often involves upsetting followed by drawing. During deformation, the contact area between the material and the hammer and anvil experiences intense friction, creating a difficult-to-deform zone. The difference in strain between the difficult and easy deformation zones, coupled with the inherent inhomogeneity of the original ingot microstructure, makes obtaining titanium alloys with a uniform and consistent microstructure extremely difficult. Conventionally, to achieve consistency in the microstructure of different parts of the billet, multi-stage forging and coupling of various deformation methods are often employed to promote a more uniform recrystallization degree in different areas. Because titanium alloys, especially high-Aleq near-α type titanium alloys and two-phase titanium alloys, inevitably develop surface defects after each forging stage during hot working, these defects need to be removed by grinding with a grinding wheel to prevent crack propagation during the next hot working stage. Therefore, excessive firing cycles mean a significant decrease in the yield of the material and a substantial increase in the cost of heat treatment, ultimately leading to a sharp rise in the production cost of the material. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a forging method that improves the uniformity of the microstructure of titanium materials, addressing the shortcomings of the prior art. This method employs a forging deformation process of "large upsetting + remelting + side upsetting and diagonal drawing" to gradually break down and refine the as-cast grains, significantly improving the grain breaking effect. It achieves alternating deformation between difficult and easy deformation zones, ultimately efficiently obtaining titanium materials with consistent microstructure, significantly reducing material processing costs, and solving the problems of difficulty in obtaining uniform microstructure and excessively high material costs associated with titanium material deformation methods.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a forging method for improving the uniformity of titanium material structure, characterized in that the method includes the following steps:

[0005] Step 1: After axial upsetting deformation of the original titanium ingot at 1150℃, it is returned to the furnace for heat preservation and then side upsetting diagonally drawn to obtain the first billet; the original titanium ingot is a titanium ingot or a titanium alloy ingot.

[0006] Step 2: The first billet obtained in Step 1 is subjected to a phase transformation at point T. βThe material is then subjected to multiple upsetting and drawing processes to obtain a second billet. During the multiple upsetting and drawing process, each upsetting and drawing process involves a large upsetting deformation followed by furnace heat preservation and side upsetting diagonal drawing.

[0007] Step 3: Apply the second billet obtained in Step 2 to the phase transformation point T. β The material is then subjected to heat treatment, and after being removed from the furnace, it is water-cooled to obtain the third billet.

[0008] Step 4: Place the third billet obtained in Step 3 at the phase transformation point T. β The fourth billet is obtained by multiple upsetting and drawing processes. In the process of multiple upsetting and drawing, each upsetting and drawing process adopts a deformation method of large upsetting deformation followed by furnace heat preservation and side upsetting diagonal drawing.

[0009] Step 5: Apply the fourth billet obtained in Step 4 to the phase transformation point T. β The material is then formed by forging to produce bar, disc, or ring forgings.

[0010] Due to the smelting characteristics of consumable metallurgy, the as-cast grain morphology of the titanium ingots or titanium alloy ingots produced is generally characterized by coarse equiaxed grains at the core and columnar grains growing at a certain angle from the outside to the inside of the ingot on the outside. To address this, this invention employs an axial upsetting deformation process in one-fire forging to fully deform the as-cast grains on the circumferential surface, obtaining sufficient energy for recrystallization. The billet after upsetting is then returned to the furnace for heat treatment and subjected to side upsetting and diagonal drawing, fully deforming the head of the billet to break up the as-cast columnar grains. This solves the problems of dead zones and as-cast grains at the head. After the initial forging using the deformation method in step one, the columnar grains in the original titanium ingot are essentially completely broken. Next, in step two of this invention, a deformation method of "cooling forging + upsetting + returning to the furnace + side upsetting and diagonal drawing" is used to further refine the equiaxed grains in the first billet. Typically, the phase transformation point T in step two... β The temperature of the multiple upsetting and drawing processes is lower than the temperature of the initial forging in step one. Then, in step three, the phase transformation point T is used. β The above heat treatment and water cooling heat treatment are carried out to obtain the original β grains with a similar microstructure and refine the primary α lamellae. In step four, the deformation method of "large upsetting + remelting + side upsetting diagonal drawing" is continued to carry out deformation in order to efficiently break the grains and realize the alternating deformation of the difficult and easy deformation zones.

[0011] The forging method described above for improving the uniformity of titanium material microstructure is characterized in that, in step one, the large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5, and the side upsetting diagonal drawing involves radially elongating the flat billet formed after the large upsetting deformation, followed by radial upsetting and axial diagonal drawing deformation, wherein the upsetting ratio for each pass is 1.8. By controlling the above-mentioned total forging ratio, side upsetting diagonal drawing method, and upsetting ratio, sufficient deformation is ensured in the core of the original titanium ingot to promote grain refinement without causing cracking.

[0012] The forging method described above for improving the uniformity of titanium microstructure is characterized in that the forging temperature of the multi-fire upsetting and drawing in step two is T. β The forging temperature is +50~100℃, and the forging passes are 1~2. The large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5. The side upsetting diagonal drawing is a deformation method in which the flat billet formed after the large upsetting deformation is drawn radially, followed by radial upsetting and axial diagonal drawing. The upsetting ratio for each pass is 1.8. By controlling the forging temperature, number of forging passes, total forging ratio, side upsetting diagonal drawing method and upsetting ratio of the above-mentioned multi-pass upsetting and drawing, sufficient deformation is ensured in the core of the first billet to promote grain refinement without cracking.

[0013] The forging method described above for improving the uniformity of titanium microstructure is characterized in that the heat treatment temperature in step three is T. β +(20~50)℃, the holding time is (0.5D+50)min~(0.5D+120)min, where D is the shortest side length of the second billet in mm. By selecting a temperature above the phase transformation point for holding, the growth of β grains is suppressed by the pinning effect of the primary α phase on the nucleation and growth of β grains, avoiding the rapid growth of β grains at high temperatures due to excessively high temperatures. By limiting the above holding time, the core of the second billet is ensured to reach the desired temperature, avoiding further growth of β grains due to excessively long holding time.

[0014] The forging method described above for improving the uniformity of titanium microstructure is characterized in that the forging temperature of the multi-fire upsetting and drawing in step four is T. β -(20~50)℃, the large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5, and the side upsetting diagonal drawing is a deformation method in which the flat billet formed after the large upsetting deformation is drawn radially, followed by radial upsetting and axial diagonal drawing, wherein the upsetting ratio of each pass is 1.7. By controlling the forging temperature, total forging ratio, side upsetting diagonal drawing method and upsetting ratio of the above-mentioned multi-fire upsetting and drawing, it is ensured that the core of the third billet obtains sufficient deformation to promote grain refinement without cracking.

[0015] The forging method described above for improving the uniformity of titanium material structure is characterized in that the forming and forging temperature in step five is T. β-(20~50)℃.

[0016] In this invention, the phase transition point T β All units are in °C.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. This invention employs a "large upsetting + remelting + side upsetting diagonal drawing" upsetting deformation method to gradually break up and refine the cast grains, significantly improving the grain breaking effect, achieving alternating deformation of difficult and easy deformation zones, and ultimately efficiently obtaining titanium materials with uniform microstructure, significantly reducing the material processing cost.

[0019] 2. The deformation process of this invention has a wide range of applications and can be applied to the forging of conventional two-phase titanium alloys such as TC4 and TC11, as well as near-α type titanium alloys such as process-pure titanium, TA18, and TA22.

[0020] 3. The deformation method of the present invention is simple, effectively reduces the number of forging passes, and achieves coordinated deformation of different parts of the billet through fewer deformation methods. It is particularly beneficial for large-size titanium materials and industrial production.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the ultrasonic flaw detection results of the TC4 titanium alloy bar prepared in Example 1 of the present invention.

[0023] Figure 2 This is a schematic diagram of the ultrasonic flaw detection results of the TC4 titanium alloy bar prepared in Comparative Example 1 of this invention.

[0024] Figure 3a This is a high-magnification microstructure image of the edge of the TA22 titanium alloy disc prepared in Example 2 of the present invention.

[0025] Figure 3b This is a high-magnification microstructure image of the core of the TA22 titanium alloy disc material prepared in Example 2 of the present invention.

[0026] Figure 4a This is a high-magnification microstructure image of the end face edge of the TC4 titanium alloy bar prepared in Example 3 of the present invention.

[0027] Figure 4b This is a high-magnification microstructure image of the core of the end face of the TC4 titanium alloy bar prepared in Example 3 of the present invention. Detailed Implementation

[0028] Example 1

[0029] This embodiment includes the following steps:

[0030] Step 1: After axial upsetting deformation of TC4 ingot at 1150℃, it is returned to the furnace for heat preservation and then subjected to side upsetting and diagonal drawing to obtain the first billet; the upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5, and the side upsetting and diagonal drawing is a deformation method in which the flat billet formed after the upsetting deformation is drawn radially, followed by radial upsetting and axial diagonal drawing, wherein the upsetting ratio of each pass is 1.8;

[0031] Step 2: The first billet obtained in Step 1 is subjected to a phase transformation at point T. β The second billet is obtained by two upsetting and drawing processes at +50℃. During the two upsetting and drawing processes, each upsetting and drawing process adopts a large upsetting deformation followed by furnace heat preservation and side upsetting diagonal drawing. The large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5. The side upsetting diagonal drawing is a method of radially elongating the flat billet formed after large upsetting deformation, followed by radial upsetting and axial diagonal drawing deformation. The upsetting ratio of each pass is 1.8.

[0032] Step 3: Apply the second billet obtained in Step 2 to the phase transformation point T. β Heat treatment is performed at +50℃ for 0.5D+50min, where D is the shortest side length of the second billet in mm. After exiting the furnace, the billet is water-cooled to obtain the third billet.

[0033] Step 4: Place the third billet obtained in Step 3 at the phase transformation point T. β The fourth billet is obtained by nine upsetting and drawing processes at -40℃. During the nine upsetting and drawing processes, each upsetting and drawing process adopts a large upsetting deformation followed by furnace heat preservation and side upsetting diagonal drawing. The large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5. The side upsetting diagonal drawing is a method of radially elongating the flat billet formed after large upsetting deformation, followed by radial upsetting and axial diagonal drawing deformation. The upsetting ratio of each pass is 1.7.

[0034] Step 5: Place the fourth billet obtained in Step 4 at T β The TC4 bar with a diameter of Φ500mm was prepared by forming and forging at -40℃.

[0035] The method in this embodiment can also be used to prepare TC4 ring forgings.

[0036] Figure 1 This is a schematic diagram of the ultrasonic flaw detection results of the TC4 titanium alloy bar prepared in this embodiment. Figure 1 It can be seen that the ultrasonic flaw detection level of different parts of the TC4 titanium alloy bar is uniform, the bar noise is uniform, and the difference is only 2dB.

[0037] Comparative Example 1

[0038] This comparative example includes the following steps:

[0039] Step 1: Perform conventional upsetting and drawing on TC4 ingots at 1150℃: first upsetting and drawing, then returning to the furnace, then upsetting and drawing again, with an upsetting ratio of 1.8 each time, to obtain the first billet;

[0040] Step 2: Sequentially apply the first billet obtained in Step 1 to the phase transformation point T. β +150℃, T β +70℃, T β The second billet is obtained by upsetting and drawing three times at a temperature above +70℃.

[0041] Step 3: Apply the second billet obtained in Step 2 to the phase transformation point T. β The process involves 11 rounds of conventional upsetting and drawing at -40℃: first, one upsetting and one drawing, then returning to the furnace, followed by one upsetting and one drawing, with an upsetting ratio of 1.7 each time, to obtain the third billet;

[0042] Step 4: Place the third billet obtained in Step 3 at T β The TC4 bar with a diameter of Φ500mm was prepared by forming and forging at -40℃.

[0043] Figure 2 This is a schematic diagram of the ultrasonic flaw detection results of the TC4 titanium alloy bar prepared in this comparative example. Figure 2 It can be seen that there are significant differences in ultrasonic testing results at different parts of the TC4 titanium alloy bar, with obvious high clutter regions at both ends, and the difference between high and low clutter is 10dB.

[0044] Will Figure 1 and Figure 2 Comparison shows that the forging method of the present invention improves the microstructure uniformity of TC4 titanium alloy bars.

[0045] Example 2

[0046] This embodiment includes the following steps:

[0047] Step 1: After axial upsetting deformation of TA22 ingot at 1150℃, it is returned to the furnace for heat preservation and then subjected to side upsetting and diagonal drawing to obtain the first billet; the upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5, and the side upsetting and diagonal drawing is a deformation method in which the flat billet formed after the upsetting deformation is drawn radially, followed by radial upsetting and axial diagonal drawing, wherein the upsetting ratio of each pass is 1.8;

[0048] Step 2: The first billet obtained in Step 1 is subjected to a phase transformation at point T. βThe second billet is obtained by two upsetting and drawing processes at +100℃. During the two upsetting and drawing processes, each upsetting and drawing process adopts a large upsetting deformation followed by furnace heat preservation and side upsetting diagonal drawing. The large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5. The side upsetting diagonal drawing is a method of radially elongating the flat billet formed after large upsetting deformation, followed by radial upsetting and axial diagonal drawing deformation. The upsetting ratio of each pass is 1.8.

[0049] Step 3: Apply the second billet obtained in Step 2 to the phase transformation point T. β Heat treatment is performed at +30℃ for 0.5D+80min, where D is the shortest side length of the second billet in mm. After exiting the furnace, the billet is water-cooled to obtain the third billet.

[0050] Step 4: Place the third billet obtained in Step 3 at the phase transformation point T. β The fourth billet is obtained by three upsetting and drawing processes at -20℃. In the multi-upsetting and drawing process, each upsetting and drawing process adopts a large upsetting deformation followed by furnace heat preservation and side upsetting diagonal drawing. The large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5. The side upsetting diagonal drawing is a method of radially elongating the flat billet formed after large upsetting deformation, followed by radial upsetting and axial diagonal drawing deformation. The upsetting ratio of each pass is 1.7.

[0051] Step 5: Place the fourth billet obtained in Step 4 at T β The TA22 disc material with a diameter of Φ700mm was prepared by forming and forging at -20℃.

[0052] Figure 3a This is a high-magnification microstructure image of the edge of the TA22 titanium alloy disc prepared in this embodiment. Figure 3a It can be seen that the microstructure consists of a uniform and fine primary α-phase + β-transformation matrix.

[0053] Figure 3b This is a high-magnification microstructure image of the core of the TA22 titanium alloy disc material prepared in Example 2 of the present invention. Figure 3b It can be seen that the microstructure is also composed of a uniform and fine primary α-phase + β-transformation matrix.

[0054] Combination Figure 3a and Figure 3b It can be seen that the microstructure of different parts of the TA22 titanium alloy disc prepared in this embodiment is basically consistent, indicating that the forging method of the present invention improves the microstructure uniformity of the TA22 titanium alloy disc.

[0055] Example 3

[0056] This embodiment includes the following steps:

[0057] Step 1: After axial upsetting deformation of TC4 ingot at 1150℃, it is returned to the furnace for heat preservation and then subjected to side upsetting and diagonal drawing to obtain the first billet; the upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5, and the side upsetting and diagonal drawing is a deformation method in which the flat billet formed after the upsetting deformation is drawn radially, followed by radial upsetting and axial diagonal drawing, wherein the upsetting ratio of each pass is 1.8;

[0058] Step 2: The first billet obtained in Step 1 is subjected to phase transformation at point T. β +100℃, T β The second billet is obtained by two upsetting and drawing processes at +50℃. During the two upsetting and drawing processes, each upsetting and drawing process adopts a large upsetting deformation followed by furnace heat preservation and side upsetting diagonal drawing. The large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5. The side upsetting diagonal drawing is a method of radially elongating the flat billet formed after large upsetting deformation, followed by radial upsetting and axial diagonal drawing deformation. The upsetting ratio of each pass is 1.8.

[0059] Step 3: Apply the second billet obtained in Step 2 to the phase transformation point T. β Heat treatment is performed at +250℃ for 0.5D+120min, where D is the shortest side length of the second billet in mm. After exiting the furnace, the billet is water-cooled to obtain the third billet.

[0060] Step 4: Place the third billet obtained in Step 3 at the phase transformation point T. β -40℃, T β -40℃, T β The fourth billet is obtained by three upsetting and drawing processes at -50℃. During the three upsetting and drawing processes, each upsetting and drawing process adopts a large upsetting deformation followed by furnace heat preservation and side upsetting diagonal drawing. The large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5. The side upsetting diagonal drawing is a method of radially elongating the flat billet formed after large upsetting deformation, followed by radial upsetting and axial diagonal drawing deformation. The upsetting ratio of each pass is 1.7.

[0061] Step 5: Place the fourth billet obtained in Step 4 at T β The TC4 bar with a diameter of Φ230mm was prepared by forming and forging at -50℃.

[0062] Figure 4a This is a high-magnification microstructure image of the end face edge of the TC4 titanium alloy bar prepared in this embodiment. Figure 4a It can be seen that the tissue morphology is equiaxed, and the primary α phase is uniform and small in size.

[0063] Figure 4b This is a high-magnification microstructure image of the core of the end face of the TC4 titanium alloy bar prepared in this embodiment. Figure 4bIt can be seen that the tissue morphology is equiaxed, and the primary α phase is uniform and small in size.

[0064] Combination Figure 4a and Figure 4b It can be seen that the microstructure of the edge and core of the TC4 titanium alloy bar prepared in this embodiment is basically the same, indicating that the forging method of the present invention improves the microstructure uniformity of the TA22 titanium alloy disc.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A forging method for improving the uniformity of titanium material microstructure, characterized in that, The method includes the following steps: Step 1: After axial upsetting deformation of the original titanium ingot at 1150℃, it is returned to the furnace for heat preservation and then subjected to side upsetting and diagonal drawing to obtain the first billet; the original titanium ingot is a titanium ingot or a titanium alloy ingot; the upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5, and the side upsetting and diagonal drawing is a deformation method in which the flat billet formed after the upsetting deformation is drawn radially, followed by radial upsetting and axial diagonal drawing, wherein the upsetting ratio of each pass is 1.8; Step 2: The first billet obtained in Step 1 is subjected to a phase transformation at point T. β The material undergoes multiple upsetting and drawing processes to obtain a second billet. During each upsetting and drawing process, a large upsetting deformation is performed followed by furnace holding and side upsetting diagonal drawing. The forging temperature of the multiple upsetting and drawing process is T. β + (50~100)℃, the forging fire is 1~2 fires, the large upsetting deformation adopts the forging method with an axial total upsetting ratio of 2.5, the side upsetting diagonal drawing is the method of drawing the flat billet formed after the large upsetting deformation along the radial direction, and then performing radial upsetting and axial diagonal drawing deformation, wherein the upsetting ratio of each pass is 1.8; Step 3: Apply the second billet obtained in Step 2 to the phase transformation point T. β The material undergoes heat treatment, followed by water cooling after being removed from the furnace to obtain the third billet; the heat treatment temperature is T. β + (20~50)℃, the holding time is (0.5D+50)min~(0.5D+120)min, where D is the shortest side length of the second billet, in mm; Step 4: Place the third billet obtained in Step 3 at the phase transformation point T. β The process involves multiple upsetting and drawing operations to obtain a fourth billet. During each upsetting and drawing operation, a large upsetting deformation is performed, followed by furnace holding and side upsetting diagonal drawing. The forging temperature for these multiple upsetting and drawing operations is T. β - (20~50)℃, the large upsetting deformation adopts a forging method with an axial total upsetting ratio of 2.5, the side upsetting diagonal drawing is a deformation method in which the flat billet formed after the large upsetting deformation is drawn radially, and then radial upsetting and axial diagonal drawing are performed, wherein the upsetting ratio of each pass is 1.7; Step 5: Apply the fourth billet obtained in Step 4 to the phase transformation point T. β The forming and forging process is carried out at a temperature of T to prepare bar, disc, or ring forgings. β - (20~50)℃.

Images