Machining deformation control method for TA31 alloy special-shaped barrel

Abstract

According to the machining deformation control method for the TA31 alloy special-shaped barrel, by preferably selecting a TA31 alloy forming process window and optimally designing the structural size of a ring rolling core mold, the situation that in the ring rolling process of the TA31 alloy special-shaped barrel, the special-shaped section area of the barrel is not filled with materials fully, the barrel cracks, and the metal machining flow line is disordered can be avoided; the forming method can ensure that the formed TA31 alloy special-shaped barrel is free of obvious macroscopic defects and reasonable in metal flow line distribution, so that the forming quality of the TA31 alloy special-shaped barrel is remarkably improved, and meanwhile, the plasticity instability phenomenon occurring in the high-temperature forming process can be effectively avoided.

Description

Technical Field

[0001] The invention relates to the technical field of plastic processing and forming of metal materials, and in particular to a processing deformation control method for a TA31 alloy special-shaped cylinder. Background Art

[0002] The 21st century is the century of the ocean. my country is committed to developing the marine economy. my country's marine engineering equipment manufacturing industry has entered a stage of rapid development. There is an urgent demand for titanium alloy equipment for marine engineering. TA31 alloy is a medium-strength and high-toughness titanium alloy independently developed by my country. It also has excellent corrosion resistance and weldability, and has great application prospects in the field of marine engineering equipment.

[0003] The pressure tank cylinder made of TA31 alloy as raw material has the advantages of light weight, strong corrosion resistance, high service reliability and long service life. However, like most titanium alloys, it has the problems of great processing difficulty, low efficiency and high cost. At the same time, the surface cracking tendency of TA31 alloy during the forming process is relatively high. Therefore, the low-cost and high-efficiency manufacturing process of TA31 alloy special-shaped cylinders has become a research focus in the field of marine engineering. At present, titanium alloy special-shaped cylinders can be nearly net-formed by ring rolling, that is, titanium alloy forging rods of certain specifications are directly formed into special-shaped cylinders of required specifications through roughing, punching, mandrel drawing, horse frame expansion and ring rolling processes. It has the advantages of high material utilization, high production efficiency and low cost. However, TA31 alloy is a medium-strength and high-toughness titanium alloy developed independently in my country. There has been little research on the hot forming process, especially the processing deformation control method during ring rolling. The ring rolling forming process parameters such as forming temperature and deformation rate are unclear. The TA31 alloy special-shaped cylinder prepared by the existing ring rolling forming process has many defects and a low dimensional qualification rate. In summary, it is urgent to explore a processing deformation control method for TA31 alloy special-shaped cylinders.

[0004] Patents CN103111557A and CN106984747A respectively disclose the ring rolling forming methods of TC25 and TC4 alloy profiled cross-section cylinders, that is, the titanium alloy is rolled into a profiled cylinder with a groove surface or a convex surface by continuous small deformation. However, there are still certain limitations. The problems that need to be solved urgently include: 1. The produced titanium alloy cylinder contains fewer convex or concave profiled areas, only one or two. The filling of the profiled area is relatively easy to control during the forming process. However, if a cylinder with multiple profiled areas is to be prepared, During the ring rolling forming process of the special-shaped cylinder, defects such as incomplete filling of the material in the special-shaped cross-section area of ​​the cylinder and easy cracking of the cylinder are likely to occur due to the large difference in the flow of metal particles in different parts. At the same time, it is easy to induce disorder of the metal processing streamline, which will damage the later service performance of the titanium alloy special-shaped cylinder. In the past, the preparation needs of cylinders with multiple special-shaped areas were mainly completed by assembling, stacking and welding multiple special-shaped cylinders with one special-shaped area, which had low production efficiency. The structural comparison diagram of the titanium alloy ring rolling forming product in the disclosed patent and the titanium alloy special-shaped cylinder produced by the target of this patent is shown in the figure Figure 1 As shown, (a) is a schematic diagram of the cylinder structure in the prior art with both inner and outer surfaces containing special-shaped areas, (b) is a schematic diagram of the cylinder structure in the prior art with one special-shaped area on the inner surface, and (c) is a schematic diagram of the cylinder structure in the present patent with multiple special-shaped areas on the inner surface; 2. The wall thickness of the titanium alloy special-shaped cylinder produced by the disclosed patent is greater than 20 mm, and it is necessary to further optimize the deformation control method to reduce the wall thickness of the special-shaped cylinder, reduce the subsequent machining amount, improve material utilization, and reduce the manufacturing cost of thin-walled special-shaped cylinders. Summary of the invention

[0005] In view of this, the present invention aims to propose a processing deformation control method for a TA31 alloy special-shaped cylinder to solve the problems of incomplete filling of the material in the special-shaped cross-section area of ​​the cylinder, cracking of the cylinder, and disordered metal processing streamlines during the ring rolling forming process of the TA31 alloy special-shaped cylinder when preparing a cylinder containing multiple special-shaped areas in the prior art.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A method for controlling the machining deformation of a TA31 alloy special-shaped cylinder comprises the following steps:

[0008] S1: Put the TA31 alloy forging bar blank into a heat treatment furnace for primary heating, the heating temperature is 940℃~970℃, the holding time is 180min~240min, after holding, the blank is upsetting and punching in sequence, after upsetting and punching, put the blank into a heat treatment furnace for secondary heating, the heating temperature is 930℃~960℃, the holding time is 60min~90min, after holding, take out the blank for mandrel drawing, after mandrel drawing, put the blank into a heat treatment furnace for tertiary heating, the heating temperature is 920℃~950℃, the holding time is 60min~90min, after holding, the blank is expanded by a rack;

[0009] S2: Based on the power dissipation factor and the Prassad instability criterion, combined with the material thermal processing diagram of TA31 alloy, the material deformation law of TA31 alloy under different deformation temperatures and deformation rates is obtained, and the ring rolling forming process window of TA31 alloy is determined;

[0010] S3: selecting the ring rolling temperature and the ring rolling rate of the first pre-ring rolling process according to the ring rolling forming process window of the TA31 alloy, placing the TA31 alloy billet into a heat treatment furnace for heating, the heating temperature is 960°C, the holding time is 50min-60min, after the holding, the billet is taken out for the first pre-ring rolling to obtain a TA31 alloy cylinder, and the TA31 alloy cylinder is cooled to room temperature and the cracks on the inner and outer surfaces of the cylinder are polished;

[0011] S4: placing the TA31 alloy special-shaped cylinder into a heat treatment furnace for heating at a temperature of 950° C. and holding the cylinder for 40 to 50 minutes. After holding the cylinder, taking the blank out for a second final ring rolling. After cooling the TA31 alloy special-shaped cylinder to room temperature, grinding the cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder.

[0012] S5: coating the inner and outer surfaces of the TA31 alloy special-shaped cylinder with an anti-oxidation coating, and then placing the TA31 alloy special-shaped cylinder in a vacuum heat treatment furnace for annealing at a heating temperature of 500°C to 700°C for a holding time of 60min to 120min. After the heat treatment, the TA31 alloy special-shaped cylinder is cooled;

[0013] S6: The inner and outer surfaces of the TA31 alloy special-shaped cylinder are machined to ensure that the specifications and dimensions of the TA31 alloy special-shaped cylinder and the roughness of the inner and outer surfaces meet the requirements.

[0014] This setting can avoid the problems of incomplete material filling in the special-shaped cross-section area of ​​the TA31 alloy special-shaped cylinder, cracking of the cylinder and disordered metal processing streamlines during the ring rolling process. It can ensure that the TA31 alloy special-shaped cylinder has no obvious macroscopic defects after forming and the metal streamlines are reasonably distributed, which significantly improves the forming quality of the TA31 alloy special-shaped cylinder and effectively avoids the plastic instability phenomenon during high-temperature forming.

[0015] Furthermore, in S1, the diameter of the forged rod blank is φ290mm~φ320mm, the height of the forged rod blank after roughening is 380mm~420mm, the punching diameter is D, 170mm≤D≤190mm, after the core shaft of the forged rod blank is stretched, the length between the end faces is 600mm~620mm, and after the hole is expanded by the rack, the inner diameter of the hole is 350mm~380mm.

[0016] The height after roughening is controlled at 380mm~420mm, which is conducive to the smooth progress of subsequent punching and drawing operations, and avoids the inconvenience of processing due to being too large or too small. The punching diameter is set to 170mm~190mm. This range not only meets the needs of subsequent processing, but also reduces material waste as much as possible and improves the overall utilization rate of materials.

[0017] Furthermore, in S2, by conducting high-temperature compression tests on the TA31 alloy under different deformation temperatures and strain rates, the true stress-true strain curve of the TA31 alloy is obtained, and the high-temperature rheological stress constitutive equation of the TA31 alloy is established based on the true stress-true strain curve data. The high-temperature rheological characteristics of the TA31 alloy are reflected by the high-temperature rheological stress constitutive equation, and the corresponding material thermal processing diagram is established based on the high-temperature rheological characteristics.

[0018] The material thermal processing diagram can intuitively display the stable and unstable areas of TA31 alloy under different processing conditions, providing guidance for formulating safe and efficient processing technology. At the same time, the material thermal processing diagram can also help optimize the process parameters and avoid defects such as cracks and uneven deformation during the processing process.

[0019] Further, in S3, after the ring rolling temperature and the ring rolling rate of the first pre-ring rolling process are determined, the size of the mandrel for the first pre-ring rolling is designed according to the finished product size of the TA31 alloy special-shaped cylinder, wherein the outer diameter of the mandrel is 300 mm, the inner diameter is 264 mm, and the height is 600 mm. The upper end, the lower end, and the space between the upper end and the lower end of the mandrel for the first pre-ring rolling are provided with a first boss, the height of the first boss is 18 mm, the width is 37 mm, and the distance between adjacent first bosses is 263 mm. mm; in S4, after determining the ring rolling temperature and ring rolling rate of the second final ring rolling, the size of the mandrel for the second final ring rolling is designed according to the size of the TA31 alloy special-shaped cylinder after pre-ring rolling, wherein the outer diameter of the mandrel is 300 mm, the inner diameter is 264 mm, and the height is 600 mm, and second bosses are arranged at the upper end, the lower end, and between the upper end and the lower end of the mandrel for the second final ring rolling, the height of the second bosses is 18 mm, the width is 74 mm, and the distance between adjacent second bosses is 26 mm.

[0020] By optimizing the design of the core mold structure dimensions, it can be ensured that the TA31 alloy special-shaped cylinder can be evenly stressed during the ring rolling process, avoiding cracking or deformation caused by local stress concentration, thereby improving the forming quality.

[0021] Furthermore, in S3, the main roll and the core roll of the ring rolling mill need to be preheated before the first pre-ring rolling; in S4, the main roll and the core roll of the ring rolling mill need to be preheated before the second final ring rolling.

[0022] Preheating the main roll and core roll can make the working area of ​​the ring rolling mill reach a more uniform temperature, which is closer to the temperature of the TA31 alloy billet, reducing the thermal stress caused by excessive temperature difference, thereby improving the plastic deformation capacity of the material and making the ring rolling process smoother.

[0023] Furthermore, air cooling is used for cooling.

[0024] The use of air cooling can avoid structural stress and cracks caused by rapid cooling, while maintaining a certain cooling rate, which is conducive to obtaining good structural properties.

[0025] Furthermore, the vacuum degree in the vacuum heat treatment furnace is not greater than 1×10 -1 Pa.

[0026] This setting can avoid oxidation of the workpiece surface and maintain the original gloss and performance of the material. Vacuum heat treatment can remove impurities such as oil, phosphorus chips, etc. on the workpiece surface, and make the workpiece surface smoother through degreasing and degassing. At the same time, since the workpiece is heated evenly during vacuum heat treatment, the temperature difference is small and the thermal stress is reduced accordingly, the deformation of the workpiece is small, which is conducive to maintaining the dimensional accuracy and shape stability of the workpiece.

[0027] Furthermore, in S6, the machining adopts turning.

[0028] Turning can remove burrs, scratches and other defects on the alloy surface and improve the overall quality of the product.

[0029] Furthermore, a grinder is used to grind the cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder. Grinding can significantly improve the roughness and flatness of the inner and outer surfaces of the cylinder, remove burrs, scratches and other defects generated during the processing, make the surface smoother and more uniform, and help improve the overall appearance quality of the product.

[0030] Compared with the prior art, the processing deformation control method of the TA31 alloy special-shaped cylinder described in the present invention has the following advantages:

[0031] It can avoid the problems of incomplete material filling in the special-shaped cross-section area of ​​the TA31 alloy special-shaped cylinder, cracking of the cylinder and disordered metal processing streamlines during the ring rolling process. It can ensure that the TA31 alloy special-shaped cylinder has no obvious macroscopic defects after forming and the metal streamlines are reasonably distributed, which significantly improves the forming quality of the TA31 alloy special-shaped cylinder and effectively avoids the plastic instability phenomenon in the high-temperature forming process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of the special-shaped region of the titanium alloy special-shaped cylinder according to an embodiment of the present invention;

[0033] Figure 2 This is a process flow chart of the forming process of the TA31 alloy special-shaped cylinder according to an embodiment of the present invention;

[0034] Figure 3 It is a design drawing of the TA31 alloy special-shaped cylinder according to an embodiment of the present invention;

[0035] Figure 4 This is a material thermal processing diagram of the TA31 alloy under the condition of true strain of 0.3 described in an embodiment of the present invention;

[0036] Figure 5 It is a dimension diagram of the ring rolling mandrel structure according to an embodiment of the present invention;

[0037] Figure 6 This is a structural dimension diagram of a TA31 alloy special-shaped cylinder after the second final ring rolling according to an embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of the cross-sectional structure of the TA31 alloy blank after punching according to an embodiment of the present invention;

[0039] Figure 8 This is a metallographic diagram of the TA31 alloy special-shaped cylinder described in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0041] Example 1

[0042] like Figure 2-7 As shown, a method for controlling the processing deformation of a TA31 alloy special-shaped cylinder comprises the following steps:

[0043] TA31 alloy forging bar billet: put the TA31 alloy forging bar with a diameter of φ290mm~φ320mm and a height of 550mm into a heat treatment furnace for primary heating at a temperature of 940℃~970℃ and a heating time of 180min~240min. After heating, the billet is subjected to roughening and punching in sequence. The height after roughening is 380mm~420mm, and the punching diameter is D, 170mm≤D≤190mm. Figure 7 As shown; after roughing and punching, the blank is placed in a heat treatment furnace for secondary heating, the heating temperature is 930℃~960℃, the holding time is 60min~90min, after holding, the blank is taken out for mandrel drawing, after the mandrel drawing is completed, the length between the end faces of the blank is 600mm~620mm, the blank is placed in a heat treatment furnace for tertiary heating, the heating temperature is 920℃~950℃, the holding time is 60min~90min, after holding, the blank is reamed with a rack, and the inner diameter is reamed to 350mm~380mm.

[0044] Through three heating treatments at different temperatures, the organizational transformation of the material can be effectively controlled to avoid coarsening of grains that may be caused by one-time high-temperature heating, thereby maintaining the fine-grained organization of the material and improving the mechanical properties and toughness of the material. Insulation is performed after each heating to ensure the uniformity of the internal temperature of the material, promote the homogenization of the organization, reduce internal stress, and improve the overall performance of the material.

[0045] Optimization of the ring rolling process window of TA31 alloy: High-temperature compression tests of TA31 alloy were carried out under a series of different deformation temperatures and strain rates to obtain the true stress-true strain curve of TA31 alloy, and the high-temperature rheological stress constitutive equation of TA31 alloy was established based on the true stress-true strain curve data. The high-temperature rheological characteristics of TA31 alloy were reflected by the high-temperature rheological stress constitutive equation, and the corresponding material thermal processing diagram was established based on the high-temperature rheological characteristics. According to the power dissipation factor and Prassad instability criterion, combined with the material thermal processing diagram, the material deformation law of TA31 alloy under different deformation temperatures and deformation rates was obtained, and the ring rolling process window of TA31 alloy was determined.

[0046] By combining the power dissipation factor with the Prassad instability criterion, the appropriate process window can be marked on the material thermal processing diagram. The specific method is to find out the areas with higher energy dissipation efficiency through the contour map of the power dissipation factor on the material thermal processing diagram. These areas usually correspond to conditions with more favorable organizational structure evolution and higher processing quality. Then, these areas are compared with the unstable areas marked by the Prassad instability criterion to eliminate the possibility of processing instability. Finally, the remaining area is the ring rolling forming process window of TA31 alloy, that is, the area where the optimal processing conditions are located. Through such analysis, the optimal processing conditions of TA31 alloy at different deformation temperatures and deformation rates can be accurately determined, thereby guiding the actual ring rolling forming process, avoiding defects such as insufficiency and cracking during material deformation, and ensuring the processing quality and performance of the finished product.

[0047] The determination of the ring rolling process window for TA31 alloy takes into account not only the deformation resistance of the alloy, but also its hot working properties, such as thermal stability and dynamic recovery recrystallization ability. By selecting appropriate process parameters, the deformation behavior of the alloy can be optimized, making it easier to achieve the desired shape and size while maintaining excellent mechanical properties and microstructure.

[0048] First pre-ring rolling: According to the TA31 alloy ring rolling forming process window, the ring rolling temperature and ring rolling rate of the first pre-ring rolling process are selected, and the size of the mandrel for the first pre-ring rolling is designed according to the finished size of the TA31 alloy special-shaped cylinder, such as Figure 5 As shown in (a), the outer diameter of the core mold is 300mm, the inner diameter is 264mm, and the height is 600mm. The upper end, the lower end, and the space between the upper end and the lower end of the core mold for the first pre-ring rolling are all provided with a first boss. The height of the first boss is 18mm, the width is 37mm, and the distance between adjacent first bosses is 263mm. The TA31 alloy billet is placed in a heat treatment furnace for heating at a heating temperature of 960°C for a holding time of 50min to 60min. After the holding, the billet is taken out for the first pre-ring rolling to obtain a TA31 alloy special-shaped cylinder. Before the first pre-ring rolling, the main roll and the core roll of the ring rolling mill need to be preheated. After the first pre-ring rolling, the TA31 alloy special-shaped cylinder is air-cooled. After cooling to room temperature, the cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder are grinded by a grinder.

[0049] The ring rolling temperature and rate selected according to the TA31 alloy ring rolling forming process window can ensure that the fluidity and deformation resistance of the alloy reach the best balance during the ring rolling process, reduce the cracking tendency during the ring rolling process, and improve the yield rate. Preheating the main roll and the core roll can reduce the thermal stress caused by temperature differences during the ring rolling process and improve the stability of the ring rolling process. At the same time, preheating can also reduce the friction between the alloy billet and the roller during ring rolling, reduce energy consumption, and improve the ring rolling efficiency. The use of air cooling can avoid the structural stress and cracks caused by rapid cooling, while maintaining a certain cooling rate, which is conducive to obtaining good structural properties.

[0050] Second final ring rolling: The ring rolling temperature and ring rolling rate of the second final ring rolling process are selected according to the TA31 alloy ring rolling forming process window, and the ring rolling temperature is not higher than the ring rolling temperature selected for the first pre-ring rolling. The size of the mandrel for the second final ring rolling is designed according to the size of the TA31 alloy special-shaped cylinder after pre-ring rolling, such as Figure 5 As shown in (b), the outer diameter of the core mold is 300mm, the inner diameter is 264mm, and the height is 600mm. The upper end, the lower end, and the space between the upper end and the lower end of the core mold for the second final ring rolling are all provided with second bosses. The height of the second bosses is 18mm, the width is 74mm, and the distance between adjacent second bosses is 26mm. The TA31 alloy special-shaped cylinder after the first pre-ring rolling is placed in a heat treatment furnace for heating. The heating temperature is 950℃, and the insulation time is 40min~50min. After insulation, the blank is taken out for the second final ring rolling. The main roll and the core roll of the ring rolling mill need to be preheated before the second final ring rolling. After the second final ring rolling, the TA31 alloy special-shaped cylinder is air-cooled. After cooling to room temperature, the cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder are grinded by a grinder.

[0051] The heating temperature of the second final ring rolling is set at 950℃, which is slightly lower than 960℃ of the first pre-ring rolling, but still within the suitable processing temperature range of TA31 alloy. This setting helps to further refine the grains and improve the mechanical properties and surface quality of the material while maintaining good plasticity and deformation ability of the material. The lower ring rolling temperature also helps to reduce oxidation and decarburization that may occur at high temperatures and protect the surface quality of the material.

[0052] Heat treatment: The inner and outer surfaces of the TA31 alloy special-shaped cylinder are coated with anti-oxidation paint and placed in a vacuum heat treatment furnace for annealing. The vacuum degree is required to be no greater than 1×10 -1 Pa, the heating temperature is 500℃~700℃, the heating time is 60min~120min, and the cooling method after heat treatment is air cooling.

[0053] Anti-oxidation coating can form a dense protective film on the surface of the alloy, effectively isolating oxygen and other corrosive media, preventing the alloy from oxidizing at high temperatures, thereby protecting the surface quality and performance of the material. The vacuum degree is required to be no greater than 1×10 -1 Pa, such a high vacuum environment can significantly reduce oxidation and decarburization during heat treatment and protect the chemical composition and organizational structure of the alloy.

[0054] Machining: Turn the inner and outer surfaces of the TA31 alloy special-shaped cylinder to make the specifications and dimensions of the TA31 alloy special-shaped cylinder and the roughness of the inner and outer surfaces meet the requirements. Turning can remove burrs, scratches and other defects on the alloy surface and improve the overall quality of the product.

[0055] Example 2

[0056] like Figure 2-3 As shown, the finished TA31 alloy special-shaped cylinder has an outer diameter of 520mm, a height of 600mm, a cylinder wall thickness of 5mm, a special-shaped interface inside, and 6 bosses, each of which has a height of 15mm and a width of 20mm. The specific implementation plan is:

[0057] TA31 alloy forging rod billet making: a TA31 alloy forging rod with a diameter of 300mm and a height of 550mm is placed in a heat treatment furnace for primary heating at a heating temperature of 970℃ and a holding time of 240min. After heating, the billet is successively roughened and punched. The height after roughening is 410mm and the punching diameter is 170mm. After roughening and punching, the billet is placed in a heat treatment furnace for secondary heating at a heating temperature of 960℃ and a holding time of 90min. After holding, the billet is taken out for mandrel drawing. After the mandrel drawing is completed, the length between the end faces of the billet is 620mm. The billet is placed in a heat treatment furnace for tertiary heating at a heating temperature of 950℃ and a holding time of 90min. After holding, the billet is reamed with a rack and the inner diameter is reamed to 360mm.

[0058] The ring rolling forming process window of TA31 alloy special-shaped cylinder is determined by using the material thermal processing diagram: the deformation temperatures are selected as 850℃, 900℃, 940℃, 980℃, and 1020℃, and the strain rate is selected as 0.01s -1 , 0.1s -1 , 1s -1 , 10s -1 , carry out high temperature compression test of TA31 alloy, obtain the corresponding true stress-true strain curve of TA31 alloy, establish the high temperature rheological stress constitutive equation of TA31 alloy according to the true stress-true strain curve data, reflect the high temperature rheological characteristics of TA31 alloy through the high temperature rheological stress constitutive equation, and establish the corresponding material thermal processing diagram according to the high temperature rheological characteristics, such as Figure 4As shown, Figure 4 The middle gray area is the material processing instability range obtained based on the power dissipation factor and the Prassad instability criterion. According to the thermal processing diagram, the processing temperature range should be between 930℃ and 960℃, and the processing rate range should be controlled within 0.01s -1 ~0.1s -1 .

[0059] First pre-ring rolling: According to the TA31 alloy ring rolling forming process window, the ring rolling temperature and ring rolling rate of the first pre-ring rolling process are selected, and the core mold structure size selected for the first pre-ring rolling of the TA31 alloy special-shaped cylinder is optimized, such as Figure 5 As shown in (a), the TA31 alloy billet is placed in a heat treatment furnace for heating at 960°C for 60 min. After the heating, the billet is taken out for the first pre-ring rolling to obtain a TA31 alloy special-shaped cylinder. The ring rolling rate is 0.1 s -1 Before the first pre-ring rolling, the main roll and core roll of the ring rolling mill need to be preheated. After the first pre-ring rolling, the TA31 alloy special-shaped cylinder is air-cooled. After cooling to room temperature, the cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder are polished using a grinder.

[0060] Second final ring rolling: According to the TA31 alloy ring rolling forming process window, the ring rolling temperature and ring rolling rate of the second final ring rolling process are selected, and the ring rolling temperature is not higher than the ring rolling temperature selected for the first pre-ring rolling. The core mold structure size selected for the second final ring rolling of the TA31 alloy special-shaped cylinder is optimized, such as Figure 5 As shown in (b), the TA31 alloy special-shaped cylinder after the first pre-ring rolling is placed in a heat treatment furnace for heating at a temperature of 950°C and a holding time of 50 minutes. After the holding time, the blank is taken out for the second final ring rolling. The main roll and the core roll of the ring rolling mill need to be preheated before the second final ring rolling. Compared with the final product, the TA31 alloy special-shaped cylinder after the second final ring rolling has a 3mm margin on one side. The structural dimensions are as follows: Figure 6 Therefore, a grinder was used to grind the cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder.

[0061] Heat treatment: The inner and outer surfaces of the TA31 alloy special-shaped cylinder are coated with anti-oxidation paint and placed in a vacuum heat treatment furnace for annealing. The vacuum degree is 8×10 -2 Pa, heating temperature is 700℃, heating time is 120min, cooling method after heat treatment is air cooling, metallographic observation is carried out after sampling of TA31 alloy special-shaped cylinder, the results are as follows Figure 8As shown, (a) is a transverse cross-section view, and (b) is a longitudinal cross-section view. The microstructure of the TA31 alloy special-shaped cylinder has no defects such as inclusions, segregation, cracks, holes, overheating, overburning, folding and uneven structure. The metallographic structure is primary equiaxed α + transformed β containing secondary lamellar α. Most of the lamellar α phases are gathered together and exist in the form of small α clusters.

[0062] Machining: Turn the inner and outer surfaces of the TA31 alloy special-shaped cylinder to make the specifications and dimensions of the TA31 alloy special-shaped cylinder and the roughness of the inner and outer surfaces meet the requirements.

[0063] The processing deformation control method of the TA31 alloy special-shaped cylinder described in the present application has the following advantages: by optimizing the TA31 alloy forming process window and optimizing the design of the ring rolling core mold structure size, it can avoid the TA31 alloy special-shaped cylinder from having incomplete material filling in the special-shaped cross-section area of ​​the cylinder, cracking of the cylinder and disordered metal processing streamlines during the ring rolling process. It can ensure that the TA31 alloy special-shaped cylinder has no obvious macroscopic defects after forming and the metal streamlines are reasonably distributed, which significantly improves the forming quality of the TA31 alloy special-shaped cylinder and can effectively avoid the plastic instability phenomenon that occurs during high-temperature forming.

[0064] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for controlling the machining deformation of a TA31 alloy special-shaped cylinder, characterized in that: The following steps are involved: S1: Put the TA31 alloy forging bar blank into a heat treatment furnace for primary heating, the heating temperature is 940℃~970℃, the holding time is 180min~240min, after holding, the blank is upsetting and punching in sequence, after upsetting and punching, put the blank into a heat treatment furnace for secondary heating, the heating temperature is 930℃~960℃, the holding time is 60min~90min, after holding, take out the blank for mandrel drawing, after mandrel drawing, put the blank into a heat treatment furnace for tertiary heating, the heating temperature is 920℃~950℃, the holding time is 60min~90min, after holding, the blank is expanded by a rack; S2: Based on the power dissipation factor and the Prassad instability criterion, combined with the material thermal processing diagram of TA31 alloy, the material deformation law of TA31 alloy under different deformation temperatures and deformation rates is obtained, and the ring rolling forming process window of TA31 alloy is determined; S3: selecting the ring rolling temperature and the ring rolling rate of the first pre-ring rolling process according to the ring rolling forming process window of the TA31 alloy, placing the TA31 alloy billet into a heat treatment furnace for heating, the heating temperature is 960°C, the holding time is 50min-60min, after the holding, the billet is taken out for the first pre-ring rolling to obtain a TA31 alloy cylinder, and the TA31 alloy cylinder is cooled to room temperature and the cracks on the inner and outer surfaces of the cylinder are polished; S4: placing the TA31 alloy special-shaped cylinder into a heat treatment furnace for heating at a temperature of 950° C. for a holding time of 40 min to 50 min. After the holding time, taking out the blank for a second final ring rolling. After cooling the TA31 alloy special-shaped cylinder to room temperature, grinding the cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder. S5: coating the inner and outer surfaces of the TA31 alloy special-shaped cylinder with an anti-oxidation coating, and then placing the TA31 alloy special-shaped cylinder in a vacuum heat treatment furnace for annealing at a heating temperature of 500°C to 700°C for a holding time of 60min to 120min. After the heat treatment, the TA31 alloy special-shaped cylinder is cooled; S6: The inner and outer surfaces of the TA31 alloy special-shaped cylinder are machined to ensure that the specifications and dimensions of the TA31 alloy special-shaped cylinder and the roughness of the inner and outer surfaces meet the requirements.

2. The method for controlling the machining deformation of a TA31 alloy special-shaped cylinder according to claim 1, characterized in that: In S1, the diameter of the forged rod blank is φ290mm~φ320mm, the height is 550mm, the height of the forged rod blank after roughening is 380mm~420mm, the punching diameter is D, 170mm≤D≤190mm, after the mandrel of the forged rod blank is stretched, the length between the end faces is 600mm~620mm, and after the horse frame expansion, the inner diameter of the hole is 350mm~380mm.

3. The processing deformation control method of TA31 alloy special-shaped cylinder according to claim 1 is characterized in that: In S2, by conducting high-temperature compression tests on TA31 alloy under different deformation temperatures and strain rates, the true stress-true strain curve of the TA31 alloy is obtained, and the high-temperature rheological stress constitutive equation of the TA31 alloy is established based on the true stress-true strain curve data. The high-temperature rheological characteristics of the TA31 alloy are reflected by the high-temperature rheological stress constitutive equation, and the corresponding material thermal processing diagram is established based on the high-temperature rheological characteristics.

4. The method for controlling the machining deformation of a TA31 alloy special-shaped cylinder according to claim 1, characterized in that: In S3, after the ring rolling temperature and the ring rolling rate of the first pre-ring rolling process are determined, the size of the mandrel for the first pre-ring rolling is designed according to the finished product size of the TA31 alloy special-shaped cylinder, wherein the outer diameter of the mandrel is 300 mm, the inner diameter is 264 mm, and the height is 600 mm. The upper end, the lower end, and the space between the upper end and the lower end of the mandrel for the first pre-ring rolling are provided with a first boss, the height of the first boss is 18 mm, the width is 37 mm, and the distance between adjacent first bosses is 263 mm. ; In S4, after determining the ring rolling temperature and ring rolling rate of the second final ring rolling, the size of the mandrel for the second final ring rolling is designed according to the size of the TA31 alloy special-shaped cylinder after pre-ring rolling, wherein the outer diameter of the mandrel is 300 mm, the inner diameter is 264 mm, and the height is 600 mm. The upper end, the lower end, and the space between the upper end and the lower end of the mandrel for the second final ring rolling are provided with second bosses, the height of the second bosses is 18 mm, the width is 74 mm, and the distance between adjacent second bosses is 26 mm.

5. The method for controlling the machining deformation of a TA31 alloy special-shaped cylinder according to claim 1, characterized in that: In S3, the main roll and the core roll of the ring rolling mill need to be preheated before the first pre-ring rolling; in S4, the main roll and the core roll of the ring rolling mill need to be preheated before the second final ring rolling.

6. The method for controlling the machining deformation of a TA31 alloy special-shaped cylinder according to claim 1, characterized in that: The cooling method is air cooling.

7. The method for controlling the machining deformation of a TA31 alloy special-shaped cylinder according to claim 1, characterized in that: The vacuum degree in the vacuum heat treatment furnace is not greater than 1×10 -1 Pa.

8. The method for controlling the machining deformation of a TA31 alloy special-shaped cylinder according to claim 1, characterized in that: In S6, machining is done by turning.

9. The method for controlling the machining deformation of a TA31 alloy special-shaped cylinder according to claim 1, characterized in that: A grinder is used to grind the cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder.

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