A method for controlling the machining deformation of TA31 alloy irregular-shaped cylinders

Abstract

This invention provides a method for controlling the processing deformation of TA31 alloy irregular-shaped cylinders. By optimizing the TA31 alloy forming process window and designing the ring rolling mandrel structure dimensions, it can avoid incomplete material filling, cylinder cracking, and disordered metal processing flow lines in the irregular cross-section area of ​​the TA31 alloy irregular-shaped cylinder during the ring rolling process. It can ensure that the TA31 alloy irregular-shaped cylinder has no obvious macroscopic defects and a reasonable distribution of metal flow lines after forming, thus significantly improving the forming quality of the TA31 alloy irregular-shaped cylinder. At the same time, it can effectively avoid the plastic instability phenomenon that occurs during high-temperature forming.

Description

Technical Field

[0001] This invention relates to the field of metal material plastic forming technology, and more specifically, to a method for controlling the deformation during the processing of TA31 alloy irregular cylindrical bodies. Background Technology

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

[0003] Pressure tank hulls made from TA31 alloy have advantages such as light weight, strong corrosion resistance, high service reliability, and long service life. However, like most titanium alloys, they also suffer from high processing difficulty, low efficiency, and high cost. In addition, TA31 alloy has a relatively high tendency to surface cracking during the forming process. Therefore, low-cost and high-efficiency manufacturing processes for TA31 alloy irregular shaped hulls have become a research focus in the field of marine engineering. At present, titanium alloy irregular shaped hulls can be nearly formed by ring rolling. That is, titanium alloy forging bars of a certain specification are directly formed into irregular shaped hulls of the required specifications through upsetting, punching, mandrel drawing, frame reaming, and ring rolling processes. This has advantages such as high material utilization, high production efficiency, and low cost. However, TA31 alloy is a medium-strength and high-toughness titanium alloy independently developed in my country. There has been little research on the processing deformation control method of hot forming process, especially the ring rolling process. The ring rolling forming process parameters such as forming temperature and deformation rate are not clear. The TA31 alloy irregular cylindrical bodies prepared by the existing ring rolling forming process have many defects and low dimensional qualification rate. Therefore, it is urgent to explore a processing deformation control method for TA31 alloy irregular cylindrical bodies.

[0004] Patents CN103111557A and CN106984747A respectively disclose ring rolling forming methods for TC25 and TC4 alloy irregular cross-section cylinders. These methods involve rolling titanium alloys into irregular cylinders with grooved or protruding surfaces using a continuous small-deformation deformation process. However, certain limitations remain, and the key challenges include: 1. The produced titanium alloy cylinders contain relatively few protruding or recessed irregular areas, only one or two. While the filling of these irregular areas is relatively easy to control during forming, it is more challenging to produce cylinders with multiple irregular areas. In the ring rolling process of irregularly shaped cylindrical bodies, defects such as incomplete material filling in the irregular cross-sectional areas and easy cracking of the cylinder are prone to occur due to large differences in the flow of metal particles in different parts. Simultaneously, it can easily induce turbulence in metal processing flow lines, impairing the later service performance of the titanium alloy irregularly shaped cylindrical body. Previously, the preparation of cylinders containing multiple irregularly shaped areas mainly involved assembling, stacking, and welding multiple cylinders containing one irregularly shaped area, resulting in low production efficiency. A structural comparison diagram of titanium alloy ring-rolled products in published patents and the titanium alloy irregularly shaped cylindrical body produced by the target of this patent is shown below. Figure 1 As shown, (a) is a schematic diagram of a cylindrical structure with irregularly shaped regions on both the inner and outer surfaces in the prior art, (b) is a schematic diagram of a cylindrical structure with one irregularly shaped region on the inner surface in the prior art, and (c) is a schematic diagram of a cylindrical structure with multiple irregularly shaped regions on the inner surface in this patent; 2. The wall thickness of the titanium alloy irregularly shaped cylindrical body produced by the published patent is greater than 20mm. It is necessary to further optimize the deformation control method to reduce the wall thickness of the irregularly shaped cylindrical body, reduce the subsequent machining amount, improve the material utilization rate, and reduce the manufacturing cost of thin-walled irregularly shaped cylindrical bodies. Summary of the Invention

[0005] In view of this, the present invention aims to propose a processing deformation control method for TA31 alloy irregular-shaped cylinders to solve the problems that easily occur in the ring rolling process of TA31 alloy irregular-shaped cylinders when preparing cylinders containing multiple irregular-shaped regions in the prior art, such as incomplete material filling in the irregular cross-sectional areas of the cylinder, cylinder cracking, and disordered metal processing flow lines.

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

[0007] A method for controlling the processing deformation of a TA31 alloy irregular-shaped cylindrical body includes the following steps:

[0008] S1: The TA31 alloy forged bar billet is placed in a heat treatment furnace for a first heating at a temperature of 940℃~970℃ and a holding time of 180min~240min. After holding, the billet is then upsetting and punched. After upsetting and punching, the billet is placed in a heat treatment furnace for a second heating at a temperature of 930℃~960℃ and a holding time of 60min~90min. After holding, the billet is removed and the mandrel is drawn. After the mandrel is drawn, the billet is placed in a heat treatment furnace for a third heating at a temperature of 920℃~950℃ and a holding time of 60min~90min. After holding, the billet is then enlarged using a frame.

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

[0010] S3: Select the ring rolling temperature and ring rolling rate of the first pre-ring rolling process according to the ring rolling forming process window of TA31 alloy. Put the TA31 alloy billet into the heat treatment furnace for heating. The heating temperature is 960℃ and the holding time is 50min~60min. After holding, take out the billet and perform the first pre-ring rolling to obtain the TA31 alloy cylinder. After cooling the TA31 alloy cylinder to room temperature, grind the cracks on the inner and outer surfaces of the cylinder.

[0011] S4: The TA31 alloy shaped cylinder is placed in a heat treatment furnace and heated to 950℃ for 40-50 minutes. After holding, the billet is taken out and subjected to a second final ring rolling. After the TA31 alloy shaped cylinder is cooled to room temperature, the cracks on the inner and outer surfaces of the TA31 alloy shaped cylinder are ground.

[0012] S5: Apply anti-oxidation coating to the inner and outer surfaces of the TA31 alloy shaped cylinder, and then place the TA31 alloy shaped cylinder into a vacuum heat treatment furnace for annealing. The heating temperature is 500℃~700℃, and the holding time is 60min~120min. After heat treatment, the TA31 alloy shaped cylinder is cooled.

[0013] S6: Machining the inner and outer surfaces of the TA31 alloy irregular-shaped cylinder to ensure that the dimensions and surface roughness of the TA31 alloy irregular-shaped cylinder meet the requirements.

[0014] This design avoids incomplete material filling, cylinder cracking, and disordered metal processing flow lines in the irregular cross-section area of ​​the TA31 alloy cylinder during ring rolling. It ensures that the TA31 alloy cylinder has no obvious macroscopic defects and a reasonable distribution of metal flow lines after forming, which significantly improves the forming quality of the TA31 alloy cylinder. At the same time, it can effectively avoid plastic instability during high-temperature forming.

[0015] Furthermore, in S1, the diameter of the forged bar billet is φ290mm~φ320mm, the height of the forged bar billet after upsetting is 380mm~420mm, the punching diameter is D, 170mm≤D≤190mm, the length between the end faces of the forged bar billet mandrel after drawing is 600mm~620mm, and the inner diameter of the hole after the frame is enlarged is 350mm~380mm.

[0016] The height after upsetting is controlled between 380mm and 420mm, which is conducive to the smooth progress of subsequent punching and drawing operations. It avoids the problem of the size being too large or too small, which would make processing difficult. The punching diameter is set between 170mm and 190mm. This range not only meets the needs of subsequent processing, but also minimizes material waste and improves the overall utilization rate of materials.

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

[0018] Material hot working diagrams can visually display the stable and unstable regions of TA31 alloy under different processing conditions, providing guidance for developing safe and efficient processing techniques. At the same time, material hot working diagrams can also help optimize process parameters and avoid defects such as cracks and uneven deformation during processing.

[0019] Furthermore, in S3, after determining the ring rolling temperature and rate for the first pre-ring rolling process, the dimensions of the mandrel for the first pre-ring rolling are designed based on the finished dimensions of the TA31 alloy shaped cylinder. The mandrel has an outer diameter of 300mm, an inner diameter of 264mm, and a height of 600mm. A first boss is provided at the upper and lower ends of the mandrel, as well as between the upper and lower ends. The first boss has a height of 18mm and a width of 37mm, and the distance between adjacent first bosses is 263mm. mm; In S4, after determining the ring rolling temperature and ring rolling rate for the second final ring rolling, the dimensions of the mandrel for the second final ring rolling are designed based on the dimensions of the TA31 alloy shaped cylinder after pre-ring rolling. The outer diameter of the mandrel is 300 mm, the inner diameter is 264 mm, and the height is 600 mm. The upper end, lower end, and the space between the upper and lower ends of the mandrel for the second final ring rolling are all provided with a second boss. The height of the second boss 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 mandrel structure dimensions, it can be ensured that the TA31 alloy irregular cylinder is subjected to uniform stress 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 core roll of the ring rolling mill need to be preheated before the first pre-ring rolling; in S4, the main roll and 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 bring the working area of ​​the ring rolling mill to a more uniform temperature, which is closer to the temperature of the TA31 alloy billet. This reduces 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.

[0024] 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 microstructure properties.

[0025] Furthermore, the vacuum degree in the vacuum heat treatment furnace is no greater than 1×10⁻⁶. -1 Pa.

[0026] This setup can prevent workpiece surface oxidation, maintain the original luster and properties of the material, and vacuum heat treatment can remove impurities such as oil and phosphorus from the workpiece surface. Through degreasing and degassing, the workpiece surface becomes smoother. At the same time, because the workpiece is heated uniformly and the temperature difference is small during vacuum heat treatment, the thermal stress is also reduced accordingly. Therefore, 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, machining is performed using turning.

[0028] Turning can remove burrs, scratches and other defects from alloy surfaces, improving the overall quality of the product.

[0029] Furthermore, a grinding machine is used to grind the cracks on the inner and outer surfaces of the TA31 alloy irregular-shaped cylinder. Grinding can significantly improve the roughness and smoothness of the inner and outer surfaces of the cylinder, remove defects such as burrs and scratches generated during processing, and make the surface smoother and more uniform, which helps to improve the overall appearance quality of the product.

[0030] Compared with existing technologies, the processing deformation control method for TA31 alloy irregular-shaped cylinders described in this invention has the following advantages:

[0031] It can avoid incomplete material filling, cylinder cracking, and disordered metal processing flow lines in the irregular cross-section area of ​​TA31 alloy cylinders during ring rolling. It can ensure that the TA31 alloy irregular cylinders have no obvious macroscopic defects and reasonable metal flow line distribution after forming, which significantly improves the forming quality of TA31 alloy irregular cylinders. At the same time, it can effectively avoid plastic instability during high-temperature forming. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the irregular region of the titanium alloy irregular cylindrical body according to an embodiment of the present invention;

[0033] Figure 2 This is a flowchart illustrating the forming process of the TA31 alloy irregular cylindrical body according to an embodiment of the present invention.

[0034] Figure 3 This is a design drawing of the TA31 alloy irregular cylindrical body according to an embodiment of the present invention;

[0035] Figure 4 This is a thermal processing diagram of the TA31 alloy described in this embodiment of the invention under a true strain of 0.3.

[0036] Figure 5 This is a dimensional diagram of the ring rolling mandrel structure described in an embodiment of the present invention;

[0037] Figure 6 This is a structural dimension diagram of the TA31 alloy irregular cylindrical body after the second final ring rolling according to an embodiment of the present invention;

[0038] Figure 7 This is a schematic cross-sectional view of the TA31 alloy billet after punching, as described in an embodiment of the present invention.

[0039] Figure 8 This is a metallographic image of the TA31 alloy irregular cylindrical body described in an embodiment of the present invention. Detailed Implementation

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be 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 irregular-shaped cylinder includes the following steps:

[0043] TA31 alloy forging billet preparation: TA31 alloy forging billets with a diameter of φ290mm~φ320mm and a height of 550mm are placed in a heat treatment furnace for a single heating process at a temperature of 940℃~970℃ for 180min~240min. After heating, the billet is sequentially upsetting and punched. The height after upsetting is 380mm~420mm, and the punching diameter is D, where 170mm≤D≤190mm. Figure 7 As shown; after upsetting and punching, the billet is placed in a heat treatment furnace for secondary heating at a temperature of 930℃~960℃ and a holding time of 60min~90min. After holding, the billet is taken out and lengthened by mandrel. After the mandrel is lengthened, the length between the end faces of the billet is 600mm~620mm. The billet is then placed in a heat treatment furnace for tertiary heating at a temperature of 920℃~950℃ and a holding time of 60min~90min. After holding, the billet is enlarged by a frame to an inner diameter of 350mm~380mm.

[0044] By performing three heating treatments at different temperatures, the microstructure transformation of the material can be effectively controlled, avoiding the grain coarsening that may result from a single high-temperature heating. This maintains the fine-grained structure of the material, improves its mechanical properties and toughness, and ensures the uniformity of internal temperature after each heating process. This promotes the homogenization of the microstructure, reduces internal stress, and improves the overall performance of the material.

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

[0046] By combining the power dissipation factor with the Prassad instability criterion, suitable process windows can be marked on the material's hot working diagram. Specifically, regions with high energy dissipation efficiency are identified on the material's hot working diagram using contour plots of the power dissipation factor. These regions typically correspond to conditions that are more favorable for microstructure evolution and higher processing quality. Then, these regions are compared with the instability regions marked by the Prassad instability criterion to eliminate the possibility of processing instability. Finally, the remaining regions are the ring rolling process windows for TA31 alloy, which are the regions with optimal processing conditions. Through this analysis, the optimal processing conditions for TA31 alloy at different deformation temperatures and deformation rates can be accurately determined, thereby guiding the actual ring rolling process, avoiding defects such as incomplete filling 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 not only considers the alloy's deformation resistance, 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 required shape and size, while maintaining excellent mechanical properties and microstructure.

[0048] First pre-ring rolling: Select the ring rolling temperature and rate for the first pre-ring rolling process based on the TA31 alloy ring rolling forming process window. Design the dimensions of the mandrel for the first pre-ring rolling based on the finished dimensions of the TA31 alloy irregular cylindrical body. Figure 5 As shown in (a), the mandrel has an outer diameter of 300 mm, an inner diameter of 264 mm, and a height of 600 mm. The upper end, lower end, and the space between the upper and lower ends of the mandrel used for the first pre-ring rolling are all 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. The TA31 alloy billet is placed in a heat treatment furnace for heating at a temperature of 960°C and a holding time of 50 min to 60 min. After holding, the billet is taken out and subjected to the first pre-ring rolling to obtain the TA31 alloy shaped cylinder. Before the first pre-ring rolling, the main roll and mandrel of the ring rolling mill need to be preheated. After the first pre-ring rolling, the TA31 alloy shaped cylinder is air-cooled. After cooling to room temperature, the cracks on the inner and outer surfaces of the TA31 alloy shaped cylinder are ground using a grinding machine.

[0049] The ring rolling temperature and rate selected according to the ring rolling process window of TA31 alloy can ensure that the fluidity and deformation resistance of the alloy reach the best balance during the ring rolling process, reduce the tendency of cracking during the ring rolling process, and improve the yield. Preheating the main roll and mandrel can reduce the thermal stress caused by temperature difference 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 rolls during the ring rolling process, reduce energy consumption, and improve the ring rolling efficiency. Using 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 microstructure and properties.

[0050] Second final ring rolling: Select the ring rolling temperature and rate for the second final ring rolling process based on the TA31 alloy ring rolling forming process window, ensuring the ring rolling temperature is not higher than the ring rolling temperature selected for the first pre-ring rolling. Design the dimensions of the mandrel for the second final ring rolling based on the dimensions of the TA31 alloy irregular cylindrical body after pre-ring rolling, such as... Figure 5 As shown in (b), the mandrel has an outer diameter of 300 mm, an inner diameter of 264 mm, and a height of 600 mm. The upper end, lower end, and the space between the upper and lower ends of the mandrel used for the second final ring rolling are all provided with a second boss. The height of the second boss is 18 mm, the width is 74 mm, and the distance between adjacent second bosses is 26 mm. The TA31 alloy shaped cylinder after the first pre-ring rolling is placed in a heat treatment furnace for heating at a temperature of 950°C for 40 min to 50 min. After holding, the billet is taken out for the second final ring rolling. Before the second final ring rolling, the main roll and mandrel of the ring rolling mill need to be preheated. After the second final ring rolling, the TA31 alloy shaped cylinder is air-cooled. After cooling to room temperature, the cracks on the inner and outer surfaces of the TA31 alloy shaped cylinder are polished using a grinding machine.

[0051] The heating temperature for the second final ring rolling is set at 950℃, slightly lower than the 960℃ of the first pre-ring rolling, but still within the suitable processing temperature range for 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 capacity. The lower ring rolling temperature also helps to reduce oxidation and decarburization that may occur at high temperatures, thus protecting the surface quality of the material.

[0052] Heat treatment: The inner and outer surfaces of the TA31 alloy irregular cylinder are coated with an anti-oxidation coating and then placed in a vacuum heat treatment furnace for annealing. The vacuum degree is required to be no greater than 1×10⁻⁶. -1 Pa, heating temperature is 500℃~700℃, heating time is 60min~120min, and cooling method after heat treatment is air cooling.

[0053] Anti-oxidation coatings can form a dense protective film on the alloy surface, effectively isolating oxygen and other corrosive media, preventing oxidation reactions at high temperatures, and thus protecting the surface quality and performance of the material. A vacuum degree of no more than 1×10⁻⁶ is required. -1 The high vacuum environment of Pa can significantly reduce oxidation and decarburization during heat treatment, protecting the chemical composition and microstructure of the alloy.

[0054] Machining: The inner and outer surfaces of the TA31 alloy irregular-shaped cylinder are machined to ensure that the dimensional specifications and surface roughness of the TA31 alloy irregular-shaped cylinder meet the requirements. Turning can remove burrs, scratches and other defects from the alloy surface, improving the overall quality of the product.

[0055] Example 2

[0056] like Figure 2-3 As shown, the finished TA31 alloy irregular-shaped cylinder has an outer diameter of 520mm, a height of 600mm, and a wall thickness of 5mm. The interior has an irregular shape with six bosses, each 15mm high and 20mm wide. The specific implementation scheme is as follows:

[0057] TA31 alloy forging billet preparation: A TA31 alloy forging billet with a diameter of 300mm and a height of 550mm is placed in a heat treatment furnace for a first heating at 970℃ for 240min. After heating, the billet is then upsetting and punched. The height after upsetting is 410mm and the punched diameter is 170mm. After upsetting and punching, the billet is placed in a heat treatment furnace for a second heating at 960℃ for 90min. After holding, the billet is removed and lengthened by mandrel drawing. After mandrel drawing, the length between the end faces of the billet is 620mm. The billet is then placed in a heat treatment furnace for a third heating at 950℃ for 90min. After holding, the billet is enlarged using a mandrel to increase the inner diameter to 360mm.

[0058] The process window for ring rolling of TA31 alloy irregular cylindrical bodies was determined using the material's thermal working diagram: deformation temperatures of 850℃, 900℃, 940℃, 980℃, and 1020℃ were selected, and a strain rate of 0.01s was chosen. -1 0.1s -1 1s -1 10s -1 High-temperature compression tests were conducted on TA31 alloy to obtain the corresponding true stress-true strain curves. Based on the true stress-true strain curve data, a high-temperature rheological stress constitutive equation for TA31 alloy was established. This equation reflects the high-temperature rheological characteristics of the TA31 alloy. Based on these characteristics, a corresponding material hot working diagram was established, such as... Figure 4As shown, Figure 4 The gray area represents the material processing instability range obtained based on the power dissipation factor and Prassad instability criterion. According to the hot working diagram, the processing temperature range should be between 930℃ and 960℃, and the processing rate should be controlled within 0.01s. -1 ~0.1s -1 .

[0059] First pre-ring rolling: Based on the TA31 alloy ring rolling forming process window, select the ring rolling temperature and rate for the first pre-ring rolling process, and optimize the design of the mandrel structure dimensions used for the first pre-ring rolling of the TA31 alloy irregular cylindrical body, such as... Figure 5 As shown in (a), the TA31 alloy billet was placed in a heat treatment furnace and heated to 960°C for 60 minutes. After holding, the billet was removed and subjected to a first pre-ring rolling to obtain a TA31 alloy shaped cylinder. The ring rolling speed was 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 ground using a grinding machine.

[0060] Second final ring rolling: Based on the TA31 alloy ring rolling forming process window, select the ring rolling temperature and rate for the second final ring rolling process, ensuring the ring rolling temperature is not higher than the ring rolling temperature selected for the first pre-ring rolling. Optimize the design of the mandrel structure dimensions selected for the second final ring rolling of the TA31 alloy irregular cylindrical body, such as... Figure 5 As shown in (b), the TA31 alloy shaped cylindrical body after the first pre-ring rolling is placed in a heat treatment furnace for heating at 950℃ for 50 minutes. After holding, the billet is removed for the second final ring rolling. Before the second final ring rolling, the main roll and core roll of the ring rolling mill need to be preheated. After the second final ring rolling, the TA31 alloy shaped cylindrical body has a 3mm allowance on each side compared to the final product. The structural dimensions are as follows: Figure 6 Therefore, a grinding machine was used to grind the cracks on the inner and outer surfaces of the TA31 alloy irregular cylinder.

[0061] Heat treatment: The inner and outer surfaces of the TA31 alloy irregular cylinder are coated with an anti-oxidation coating and then placed in a vacuum heat treatment furnace for annealing at a vacuum degree of 8×10. -2 Pa, heating temperature 700℃, heating time 120min, cooling method after heat treatment is air cooling, metallographic observation was performed on samples of TA31 alloy irregular-shaped cylinders after sampling. The results are as follows: Figure 8As shown, (a) is a transverse cross-section and (b) is a longitudinal cross-section. The microstructure of the TA31 alloy irregular cylinder is free of defects such as inclusions, segregation, cracks, pores, overheating, burning, folding and uneven structure. The metallographic structure is primary equiaxed α + transformation β containing secondary lamellar α. Most of the lamellar α phases are aggregated together and exist in the form of small α bundles.

[0062] Machining: The inner and outer surfaces of the TA31 alloy irregular cylinder are machined by turning to ensure that the dimensional specifications of the TA31 alloy irregular cylinder and the surface roughness of the inner and outer surfaces meet the requirements.

[0063] The processing deformation control method for TA31 alloy irregular cylinders described in this application has the following advantages: By optimizing the TA31 alloy forming process window and designing the ring rolling mandrel structure dimensions, it is possible to avoid incomplete material filling, cylinder cracking, and disordered metal processing flow lines in the irregular cross-section area of ​​the TA31 alloy irregular cylinder during the ring rolling process. This ensures that the TA31 alloy irregular cylinder has no obvious macroscopic defects and a reasonable distribution of metal flow lines after forming, which significantly improves the forming quality of the TA31 alloy irregular cylinder. At the same time, it can effectively avoid plastic instability during high-temperature forming.

[0064] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for controlling the deformation of a TA31 alloy profiled cylinder, characterized by, The method comprises the following steps: S1: put the TA31 alloy forging bar blank into a heat treatment furnace for primary heating, the heating temperature is 940-970 DEG C, the holding time is 180-240 min, after holding, the blank is sequentially subjected to upsetting and piercing, after upsetting and piercing, the blank is put into the heat treatment furnace for secondary heating, the heating temperature is 930-960 DEG C, the holding time is 60-90 min, after holding, the blank is taken out for mandrel lengthening, after mandrel lengthening, the blank is put into the heat treatment furnace for tertiary heating, the heating temperature is 920-950 DEG C, the holding time is 60-90 min, after holding, the blank is subjected to mandrel hole expansion; S2: according to the power dissipation factor and the Prassad instability criterion, in combination with the material processing map of the TA31 alloy, the material deformation law of the TA31 alloy under different deformation temperatures and different deformation rates is obtained, and the ring rolling forming process window of the TA31 alloy is determined; Through high-temperature compression test of the TA31 alloy under different deformation temperatures and different strain rates, the true stress-true strain curve of the TA31 alloy is obtained, the high-temperature flow stress constitutive equation of the TA31 alloy is established according to the true stress-true strain curve data, the high-temperature flow characteristics of the TA31 alloy are reflected through the high-temperature flow stress constitutive equation, and the corresponding material processing map is established according to the high-temperature flow characteristics; S3: according to the ring rolling forming process window of the TA31 alloy, the ring rolling temperature and the ring rolling speed of the first pre-ring rolling process are selected, the size of the first pre-ring rolling core mold is designed according to the finished product size of the TA31 alloy shaped cylinder, wherein the outer diameter of the core mold is 300 mm, the inner diameter is 264 mm, and the height is 600 mm, the upper end, the lower end and the portion between the upper end and the lower end of the first pre-ring rolling core mold are all provided with first bosses, the height of the first boss is 18 mm, the width is 37 mm, and the distance between adjacent first bosses is 263 mm; the TA31 alloy blank is put into a heat treatment furnace for heating, the heating temperature is 960 DEG C, and the holding time is 50-60 min, after holding, the blank is taken out for the first pre-ring rolling to obtain a TA31 alloy cylinder, and the cracks on the inner and outer surfaces of the TA31 alloy cylinder are polished after being cooled to room temperature; S4: the TA31 alloy shaped cylinder is put into a heat treatment furnace for heating, the heating temperature is 950 DEG C, and the holding time is 40-50 min, after holding, the blank is taken out for the second final ring rolling, the size of the second final ring rolling core mold is designed according to the size of the TA31 alloy shaped cylinder after pre-ring rolling, wherein the outer diameter of the core mold is 300 mm, the inner diameter is 264 mm, and the height is 600 mm, the upper end, the lower end and the portion between the upper end and the lower end of the second final ring rolling core mold are all provided with second bosses, the height of the second boss is 18 mm, the width is 74 mm, and the distance between adjacent second bosses is 26 mm; the cracks on the inner and outer surfaces of the TA31 alloy shaped cylinder are polished after being cooled to room temperature. S5: The inner and outer surfaces of the TA31 alloy special-shaped cylinder are coated with anti-oxidation paint, and then the TA31 alloy special-shaped cylinder is placed in a vacuum heat treatment furnace for annealing treatment, the heating temperature is 500-700 DEG C, the holding time is 60-120 min, and the TA31 alloy special-shaped cylinder is cooled after heat treatment; S6: The inner and outer surfaces of the TA31 alloy special-shaped cylinder are machined, so that the size and roughness of the inner and outer surfaces of the TA31 alloy special-shaped cylinder meet the requirements.

2. The method of controlling working deformation of a TA31 alloy contoured cylinder according to claim 1, characterized by, In S1, the diameter of the forging bar stock is φ290-φ320 mm, the height is 550 mm, the height of the forged bar stock after upsetting is 380-420 mm, the punching diameter is D, 170≤D≤190 mm, the length between the end faces of the forged bar stock after core shaft drawing is 600-620 mm, and the inner diameter of the hole after the horse frame hole expansion is 350-380 mm.

3. The method of controlling working deformation of a TA31 alloy contoured cylinder according to claim 1, characterized by, In S3, the main roller and core roller of the ring rolling machine need to be preheated before the first pre-ring rolling, and in S4, the main roller and core roller of the ring rolling machine need to be preheated before the second final ring rolling.

4. The method of controlling working deformation of a TA31 alloy contoured cylinder according to claim 1, characterized by, The cooling mode is air cooling.

5. The method of controlling working deformation of a TA31 alloy contoured cylinder according to claim 1, characterized by, The vacuum degree in the vacuum heat treatment furnace is not more than 1x10-1 Pa.

6. The method of controlling working deformation of a TA31 alloy contoured cylinder according to claim 1, characterized by In S6, the machining adopts turning.

7. The method of controlling working deformation of a TA31 alloy contoured cylinder according to claim 1, wherein The cracks on the inner and outer surfaces of the TA31 alloy special-shaped cylinder are polished by a polisher.

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