Preparation method of high-plasticity TA15 titanium alloy pipe

Abstract

The invention is applicable to the technical field of titanium alloy pipe processing, and particularly relates to a preparation method of a high-plasticity TA15 titanium alloy pipe, which comprises the following steps: step S1, selecting sponge titanium, pure metal and intermediate alloy, preparing according to standard components of TA15 titanium alloy to obtain a prepared raw material, and smelting the prepared raw material for three times by adopting a vacuum consumable smelting furnace to obtain a high-plasticity TA15 titanium alloy pipe; and the TA15 titanium alloy cast ingot with the diameter being 600 mm is obtained. According to the method, the mechanical property and plasticity of the titanium alloy pipe are remarkably improved by accurately controlling the temperature and deformation of each machining step. And three-time upsetting and three-time drawing forging is carried out within the temperature range of T beta or above, coarse grains are effectively crushed, and grain structures are refined. And then, the metallographic structure of the wool rod is gradually optimized by accurately controlling the forging temperature and the deformation amount.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy pipe processing, in particular to a method for preparing a high-plasticity TA15 titanium alloy pipe. Background Art

[0002] As an important high-strength titanium alloy material, TA15 titanium alloy is widely used in aerospace, military and other fields. It has excellent corrosion resistance, strength and toughness, and plays an important role in the manufacture of high-performance structural parts and important components. The conventional TA15 titanium alloy pipe preparation method usually includes multiple links such as ingot casting, forging, perforation, hot rolling and heat treatment. However, the preparation process in the prior art still faces some significant challenges and technical bottlenecks, which affect product quality and production efficiency, especially in the preparation process of large-diameter thin-walled pipes.

[0003] First, during the ingot casting stage, due to the traditional smelting process and the control of alloy composition, the composition of the ingot is often uneven or the microstructure is not ideal, which affects the stability of subsequent processing and the mechanical properties of the metal. During the forging process, especially under conditions of large deformation, the grains are prone to coarsening, resulting in insufficient plasticity of the titanium alloy, and defects such as inclusions and cracks are prone to occur, further affecting the quality of the material and the controllability of subsequent processing. Although temperature control measures are adopted in the prior art, it is difficult to achieve effective control of grain refinement due to insufficient control accuracy of deformation and temperature, which affects the mechanical properties of the product.

[0004] Secondly, during the pipe piercing and hot rolling process, due to improper control of temperature and deformation, the internal structure of the pipe billet is prone to unevenness, resulting in large differences in its mechanical properties and plasticity. The traditional oblique piercing and hot rolling processes have certain limitations in the control of piercing temperature and deformation rate, and often cannot meet the requirements of large diameter and thin wall at the same time. High compression rate and excessive wall reduction may cause defects such as cracks and holes on the surface or inside of the pipe, affecting the forming quality of the pipe and the subsequent processing accuracy. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a method for preparing a high-plasticity TA15 titanium alloy tube, aiming to solve the technical problems mentioned in the background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a high-plasticity TA15 titanium alloy pipe comprises the following steps:

[0008] Step S1: sponge titanium, pure metal and master alloy are selected and prepared according to the standard composition of TA15 titanium alloy to obtain a prepared raw material, and the prepared raw material is melted three times in a vacuum consumable melting furnace to obtain a TA15 titanium alloy ingot with a diameter of 600 mm;

[0009] Step S2: Cut the TA15 titanium alloy ingot into small segments of preset weight using a sawing machine, and determine its β transformation temperature T by metallographic analysis. β The surface of the TA15 titanium alloy ingot is coated with a high temperature heat-resistant coating and placed in a resistance furnace and heated in stages to T β Above 50-100℃;

[0010] Step S3: after heating the TA15 titanium alloy ingot to 50-100° C. above Tβ, using a 2000T rapid forging machine to perform three-upsetting and three-drawing forging on the TA15 titanium alloy ingot;

[0011] Step S4: grinding and repairing the surface of the forged TA15 titanium alloy ingot, applying a special high temperature resistant coating on the surface of the TA15 titanium alloy ingot, and placing the TA15 titanium alloy ingot into a resistance furnace for segmented heating. β The deformation forging is carried out at 10-20℃ below, and the deformation amount is controlled at 60-80%. The billet is forged to an outer diameter of 300-500mm. Subsequently, the surface of the billet is painted with high temperature resistant paint again, and it is placed in a resistance furnace for segmented heating. β The rough rod is forged at 20-50°C, and the deformation is controlled at 40-60%, until the TA15 titanium alloy round rod with an outer diameter of 160-300 mm is forged;

[0012] Step S5: Drill a hole in the center of the TA15 titanium alloy round rod with a diameter of not less than 40 mm, apply high-temperature paint on the surface of the drilled TA15 titanium alloy round rod, place it in a resistance furnace and heat it to 700-750°C, and then raise the temperature to T β Below 10-25°C, a three-roller cross-rolling piercing machine is used to obtain a TA15 titanium alloy tube blank with a diameter-to-thickness ratio of 5-10:1;

[0013] Step S6: Place the TA15 titanium alloy tube blank into a resistance furnace and heat it to 700-750°C, then raise the temperature to T β Below 50-100℃, use four-pass continuous rolling equipment to reduce the diameter and wall in multiple passes until the diameter-to-thickness ratio of the TA15 titanium alloy tube billet is 10-40:1;

[0014] Step S7: using a tube stripping machine to strip the tube, removing the tube core, and using the residual heat to straighten the tube using a six-roller straightening machine to eliminate internal stress and deformation, thereby obtaining a TA15 titanium alloy tube;

[0015] Step S8: Place the TA15 titanium alloy tube into a resistance furnace for heat treatment, and control the temperature within a preset temperature range. After the heat treatment, use a saw to cut the tube, remove burrs at both ends, and perform flattening. Finally, lathe the oxide scale on the inner and outer surfaces of the TA15 titanium alloy tube.

[0016] Further, in step S2, the preset weight is 500-1000kg.

[0017] Furthermore, in step S3, the single deformation amount is controlled to be 1.5-2.0, and the total deformation amount is 6-8.

[0018] Furthermore, in step S4, the total deformation is controlled within a range of 60-80%.

[0019] Furthermore, in step S5, the compression rate of the oblique rolling and punching is controlled at 8-12%, and the wall reduction is 30-60%.

[0020] Furthermore, in step S6, the wall reduction amount in each pass is controlled to be 2-8 mm, the total wall reduction amount is 8-32 mm, and the outer diameter is reduced by 16-64 mm.

[0021] Furthermore, in step S8, the heat treatment temperature is controlled at 750-850°C.

[0022] The present invention provides a method for preparing a high-plasticity TA15 titanium alloy pipe, which has the following beneficial effects:

[0023] The beneficial effects of the present invention are mainly reflected in that the mechanical properties and plasticity of titanium alloy pipes are significantly improved by precisely controlling the temperature and deformation of each processing step. Three-upsetting and three-drawing forging is carried out within a temperature range above Tβ, which effectively breaks up the coarse grains and refines the grain structure. Subsequently, the metallographic structure of the rough rod is gradually optimized by precisely controlling the forging temperature and deformation. Titanium alloys have strong tissue heredity, so achieving a more ideal tissue structure before perforation plays a vital role in improving the subsequent perforation performance, tissue uniformity and plasticity of the pipe, ensuring the forming quality and performance of the final product.

[0024] In addition, the piercing temperature can be reduced to below Tβ after drilling the hole in the light rod. This process optimization effectively avoids the damage of high temperature to the forged structure. During the piercing process, the precise control of the oblique rolling piercing further improves the plasticity of the pipe and ensures the uniformity of the internal structure of the pipe blank. The application of the four-rolling process not only reduces the processing temperature, but also further refines the grains through a large deformation amount, significantly improving the mechanical properties of the pipe, especially the strength and corrosion resistance.

[0025] The flexibility of the four-rolling equipment enables the effective processing of pipes with different diameter-to-thickness ratios, especially for the rolling of high-strength titanium alloy pipes. The four-rolling process solves the problem of production difficulties. Its efficient deformation control greatly saves processing time and cost, while improving labor productivity, with significant economic benefits. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0028] A method for preparing a high-plasticity TA15 titanium alloy pipe provided in an embodiment of the present invention comprises the following steps:

[0029] Step S1: Raw material preparation and smelting

[0030] Sponge titanium, pure metal and intermediate alloy are selected and prepared according to the standard composition of TA15 titanium alloy to obtain preliminary raw materials, which are melted three times in a vacuum consumable melting furnace to obtain a TA15 titanium alloy ingot with a diameter of 600 mm.

[0031] Step S2: Pre-forging treatment

[0032] The TA15 titanium alloy ingot was cut into small segments of preset weight by sawing machine, and its β transformation temperature T was determined by metallographic analysis. β The surface of the TA15 titanium alloy ingot is coated with a high temperature heat-resistant coating and placed in a resistance furnace and heated in stages to T β Above 50-100℃.

[0033] Step S3: Initial forging and grain refinement

[0034] After the TA15 titanium alloy ingot is heated to 50-100℃ above Tβ, a 2000T rapid forging machine is used to perform three-upsetting and three-drawing forging on the TA15 titanium alloy ingot. Through this forging process, the coarse grains of the alloy are completely broken, ensuring grain refinement and improving the plasticity and mechanical properties in subsequent processing.

[0035] Step S4: Forging and finishing

[0036] The forged TA15 titanium alloy ingot is surface-grinded and defect-repaired, and the surface of the TA15 titanium alloy ingot is coated with a special high-temperature resistant coating. The TA15 titanium alloy ingot is placed in a resistance furnace for segmented heating. βThe deformation forging is carried out at 10-20℃ below, and the deformation amount is controlled at 60-80%. The billet is forged to an outer diameter of 300-500mm. Subsequently, the surface of the billet is painted with high temperature resistant paint again, and it is placed in a resistance furnace for segmented heating. β The rough rod is forged at 20-50℃, and the deformation is controlled at 40-60% until it is forged into a TA15 titanium alloy round rod with an outer diameter of 160-300mm. β The following deformation forging is carried out to further optimize the metallographic structure and improve the plasticity and forgeability of the alloy.

[0037] First, in T β Three upsetting and three drawing forgings are performed within the above temperature range to effectively break up the coarse grains and refine the organization; then, the metallographic structure of the rough rod is gradually optimized by precisely controlling the forging temperature and deformation. Since the organization of titanium alloy has strong heredity, if a relatively ideal organization structure is achieved before perforation, it will play a vital role in the subsequent perforation performance, organization uniformity and plasticity improvement of the pipe.

[0038] Step S5: Through-hole drilling and oblique rolling perforation

[0039] Drill a hole in the center of the TA15 titanium alloy round bar with a diameter of no less than 40 mm, apply high-temperature paint on the surface of the drilled TA15 titanium alloy round bar, put it into a resistance furnace and heat it to 700-750℃, and then heat it to T β Below 10-25 ℃, a three-roller cross-rolling piercing machine is used to obtain a TA15 titanium alloy tube billet with a diameter-to-thickness ratio of 5-10:1.

[0040] Step S6: Hot rolling and efficient deformation

[0041] The TA15 titanium alloy tube billet is placed in a resistance furnace and heated to 700-750°C, and then heated to T β Below 50-100℃, four-pass continuous rolling equipment is used to reduce the diameter and wall in multiple passes until the diameter-to-thickness ratio of the TA15 titanium alloy tube billet is 10-40:1.

[0042] Step S7: Tube removal and straightening

[0043] The tube was removed by a tube stripping machine and the tube core was removed. The residual heat was utilized and a six-roller straightening machine was used for straightening to eliminate internal stress and deformation, thereby obtaining a TA15 titanium alloy tube.

[0044] Step S8: Heat treatment and final processing

[0045] The TA15 titanium alloy pipe is placed in a resistance furnace for heat treatment, and the temperature is controlled within the preset temperature range. After heat treatment, a saw is used to cut the material, remove burrs at both ends, and perform flat head processing. Finally, the oxide scale on the inner and outer surfaces of the TA15 titanium alloy pipe is machined.

[0046] In one embodiment of the present invention, the preparation method of the present invention can effectively improve the overall performance and production efficiency of TA15 titanium alloy pipes, especially the innovative design in temperature control. First, in the initial processing stage of the ingot, the ingot is heated to T β The high temperature treatment ensures the complete crushing of coarse grains and promotes grain refinement, laying the foundation for subsequent deformation and organization optimization. This treatment not only improves the plasticity of the material, but also avoids the forging difficulties and crack formation caused by too low temperature, effectively enhancing the material's machinability and overall structural stability.

[0047] At the same time, during the subsequent forging and processing, the temperature is strictly controlled at T β To ensure that the grains are refined during the deformation process, the adverse effects of excessive temperature on the titanium alloy structure are avoided. β The following deformation forging can effectively avoid excessive grain coarsening and thermal damage of titanium alloy at high temperature, ensure the uniformity and stability of alloy structure, and optimize the mechanical properties of pipe. By controlling the temperature range, it can meet the processing requirements of pipe and ensure the plasticity, strength and durability of the final product.

[0048] Furthermore, in the four-roll process, β Performing multiple reductions at a temperature of 50-100°C can fully utilize the effect of temperature on material deformation, while controlling the appropriate temperature range to avoid grain coarsening or excessive oxide scale formation caused by excessive temperature. This step not only optimizes the microstructure of the pipe, but also improves production efficiency and significantly improves the strength and toughness of the pipe.

[0049] In the subsequent heat treatment, tube removal and straightening stages, the use of lower temperature treatment can effectively eliminate the internal stress in the material, while avoiding unnecessary structural changes caused by excessively high temperatures, further stabilizing the size and shape of the tube and ensuring its reliability in high-strength applications.

[0050] In summary, the present invention effectively avoids the adverse effects that may be caused by high-temperature processing while ensuring the optimization of plasticity and mechanical properties of TA15 titanium alloy pipes during the production process through reasonable temperature setting and control. This method not only improves the overall performance of titanium alloy pipes, but also greatly improves production efficiency, reduces costs, and has high application value.

[0051] In this embodiment, in step S2, the preset weight is 500-1000 kg.

[0052] This setting helps optimize the melting process of the ingot and ensures that the ingot obtained from each melting has sufficient quality to meet the requirements of subsequent forging and processing. A larger ingot weight can provide better temperature control and stability, reduce the problem of uneven composition or uneven distribution of impurities that may occur during the melting process, thereby ensuring the uniformity and melting quality of the alloy and improving the efficiency and material properties of subsequent processing.

[0053] In this embodiment, in step S3, the single deformation amount is controlled to be 1.5-2.0, and the total deformation amount is 6-8.

[0054] This deformation control range helps to ensure that coarse grains are effectively broken and refined during the initial forging stage without excessive deformation causing cracks or damage to the material. The single deformation is controlled between 1.5-2.0 to ensure uniform deformation of the material during each forging process and avoid local stress concentration in the material, thereby improving the plasticity of the titanium alloy and the smoothness of subsequent processing. A total deformation of 6-8 can further enhance the mechanical properties of the alloy while ensuring processing stability and product consistency.

[0055] In this embodiment, in step S5, the compression rate of the oblique rolling and punching is controlled at 8-12%, and the wall reduction is 30-60%.

[0056] This control of compression rate and wall reduction can effectively improve the plasticity of the material during the perforation process and reduce defects in the perforation process, such as cracks and uneven deformation. At the same time, controlling the compression rate at 8-12% and the wall reduction at 30-60% can optimize the initial shape of the tube billet and provide a good foundation for subsequent rolling and heat treatment. Reasonable temperature control and deformation during the perforation process ensure that the organizational structure of the tube billet is more uniform, further improving the mechanical properties and plasticity of the tube.

[0057] In this embodiment, in step S6, the wall reduction amount in each pass is controlled to be 2-8 mm, the total wall reduction amount is 8-32 mm, and the outer diameter is reduced by 16-64 mm.

[0058] Controlling the wall reduction between 2-8mm in each pass helps to achieve stable tube deformation, ensure the forming quality of the tube, and reduce cracks or internal stress caused by excessive deformation. At the same time, appropriate wall reduction can effectively refine the grains and improve the overall strength and toughness of titanium alloy tubes. The total wall reduction reaches 8-32mm, so that the tube can meet the production requirements of different specifications of tubes while ensuring strength and stability. The outer diameter reduction of 16-64mm can meet the processing requirements of high-strength tubes, while optimizing the dimensional accuracy and surface quality of the tubes.

[0059] In this embodiment, in step S8, the heat treatment temperature is controlled at 750-850°C.

[0060] This temperature control range can ensure that the phase change during the heat treatment process is fully carried out, effectively improving the uniformity of the tube's structure and mechanical properties. Heat treatment within the range of 750-850℃ can refine the grains and eliminate the internal stress during the heat treatment process, thereby improving the corrosion resistance, strength, plasticity and fatigue resistance of the tube. At the same time, a reasonable heat treatment temperature can also avoid excessive grain coarsening caused by excessive temperature, maintain the good performance of the material, and ensure that the final product can meet the strict requirements of industrial applications.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a high-plasticity TA15 titanium alloy pipe, characterized in that: The following steps are involved: Step S1: sponge titanium, pure metal and master alloy are selected and prepared according to the standard composition of TA15 titanium alloy to obtain a prepared raw material, and the prepared raw material is melted three times in a vacuum consumable melting furnace to obtain a TA15 titanium alloy ingot with a diameter of 600 mm; Step S2: Cut the TA15 titanium alloy ingot into small segments of preset weight using a sawing machine, and determine its β transformation temperature T by metallographic analysis. β The surface of the TA15 titanium alloy ingot is coated with a high temperature heat-resistant coating and placed in a resistance furnace and heated in stages to T β Above 50-100℃; Step S3: after heating the TA15 titanium alloy ingot to 50-100° C. above Tβ, using a 2000T rapid forging machine to perform three-upsetting and three-drawing forging on the TA15 titanium alloy ingot; Step S4: grinding and repairing the surface of the forged TA15 titanium alloy ingot, applying a special high temperature resistant coating on the surface of the TA15 titanium alloy ingot, and placing the TA15 titanium alloy ingot into a resistance furnace for segmented heating. β The deformation forging is carried out at 10-20℃ below, and the deformation amount is controlled at 60-80%. The billet is forged to an outer diameter of 300-500mm. Subsequently, the surface of the billet is painted with high temperature resistant paint again, and it is placed in a resistance furnace for segmented heating. β The rough rod is forged at 20-50°C, and the deformation is controlled at 40-60%, until the TA15 titanium alloy round rod with an outer diameter of 160-300 mm is forged; Step S5: Drill a hole in the center of the TA15 titanium alloy round rod with a diameter of not less than 40 mm, apply high-temperature paint on the surface of the drilled TA15 titanium alloy round rod, place it in a resistance furnace and heat it to 700-750°C, and then raise the temperature to T β Below 10-25°C, a three-roller cross-rolling piercing machine is used to obtain a TA15 titanium alloy tube blank with a diameter-to-thickness ratio of 5-10:1; Step S6: Place the TA15 titanium alloy tube blank into a resistance furnace and heat it to 700-750°C, then raise the temperature to T β Below 50-100℃, use four-pass continuous rolling equipment to reduce the diameter and wall in multiple passes until the diameter-to-thickness ratio of the TA15 titanium alloy tube billet is 10-40:1; Step S7: using a tube stripping machine to strip the tube, removing the tube core, and using the residual heat to straighten the tube using a six-roller straightening machine to eliminate internal stress and deformation, thereby obtaining a TA15 titanium alloy tube; Step S8: Place the TA15 titanium alloy tube into a resistance furnace for heat treatment, and control the temperature within a preset temperature range. After the heat treatment, use a saw to cut the tube, remove burrs at both ends, and perform flattening. Finally, lathe the oxide scale on the inner and outer surfaces of the TA15 titanium alloy tube.

2. The method for preparing a high-plasticity TA15 titanium alloy pipe according to claim 1, characterized in that: In step S2, the preset weight is 500-1000kg.

3. The method for preparing a high-plasticity TA15 titanium alloy pipe according to claim 1, characterized in that: In step S3, the single deformation amount is controlled at 1.5-2.0, and the total deformation amount is 6-8.

4. The method for preparing a high-plasticity TA15 titanium alloy pipe according to claim 1, characterized in that: In step S5, the compression rate of the oblique rolling and punching is controlled at 8-12%, and the wall reduction is 30-60%.

5. The method for preparing a high-plasticity TA15 titanium alloy pipe according to claim 1, characterized in that: In step S6, the wall reduction amount in each pass is controlled to be 2-8 mm, the total wall reduction amount is 8-32 mm, and the outer diameter is reduced by 16-64 mm.

6. The method for preparing a high-plasticity TA15 titanium alloy pipe according to claim 1, characterized in that: In step S8, the heat treatment temperature is controlled at 750-850°C.