Processing and manufacturing method of superheated titanium alloy

Abstract

The present invention discloses a processing and manufacturing method for a heat-strengthened titanium alloy, specifically including the following steps: Step 1, fully mixing granular or chipped raw materials and then setting aside; Step 2, fabricating a consumable electrode according to the product obtained in Step 1; Step 3, placing the consumable electrode obtained in Step 2 in a vacuum consumable arc furnace for melting to form a titanium alloy ingot; Step 4, performing forging processing on the titanium alloy ingot obtained in Step 3 to obtain a finished forged blank. The present invention solves the problem that it is difficult to control the microstructure uniformity of high-temperature titanium alloys. The high-temperature titanium alloy forged blank prepared by the present invention has high thermal strength and good thermal stability, and can meet the requirements of industrial mass production and use.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy preparation, and relates to a processing and manufacturing method for strongly heated titanium alloy. Background Art

[0002] Due to the high specific strength, specific stiffness and good high-temperature mechanical properties of high-temperature titanium alloys, they are widely used in aircraft, engines, and spacecraft to manufacture various components used under high-temperature and high-pressure conditions, such as compressor disks, drums, fuel tanks, rocket casings, etc. Since the 1950s, countries around the world have successively developed a series of high-temperature titanium alloys and began to apply them to aeroengines, significantly reducing the structural weight of the engines, increasing the thrust-to-weight ratio and structural efficiency, and playing a huge role in the development of aeroengines. So far, the service temperature of maturely applied high-temperature titanium alloys has reached 600°C, such as high-temperature titanium alloys like IMI834 in the UK, Ti-1100h in the US, and Ti60 in China, among which the most representative is IMI834 titanium alloy. At the same time, with the increasing requirements such as the increase in the flight altitude and speed of high-altitude and high-speed aircraft and the thrust-to-weight ratio of aeroengines, the working temperature of high-temperature titanium alloys needs to be further increased, and there is an urgent need for titanium alloys with a service temperature of 650°C.

[0003] At present, the 600°C titanium alloys at home and abroad are mainly near-α type, and the main elements added are generally Al, Sn, Zr, Mo, Nb, Si, C, etc. The tensile strength of this type of titanium alloy at 600°C is generally about 660 MPa. Under the stress conditions of 600°C and 340 MPa, it can maintain no fracture for more than 100 h. The creep performance can have a residual deformation less than 0.2% under the conditions of 600°C, 160 MPa, and 100 h. However, under the stress conditions of 620°C and 340 MPa, the holding time without fracture is shortened to less than 20 h, and the creep performance has a residual deformation greater than 0.3% under the conditions of 620°C, 160 MPa, and 100 h. It can be seen that when the service temperature of the 600°C titanium alloy is increased to 620°C, its performance drops sharply, and it cannot meet the design requirements of part life and safety reliability. In order to meet the requirements of a service temperature of 650°C, it is necessary to re-optimize the composition design of high-temperature titanium alloys and conduct in-depth research on their ingot melting and forging processing technologies, solve problems such as composition optimization, composition uniformity control, and microstructure uniformity control of 650°C titanium alloys, and achieve the industrial batch production conditions of 650°C titanium alloy products. Summary of the Invention

[0004] The purpose of the present invention is to provide a processing and manufacturing method for strongly heated titanium alloy, which solves the problem that it is difficult to control the microstructure uniformity of high-temperature titanium alloys.

[0005] The technical solution adopted by the present invention is a method for processing and manufacturing a strong heat-resistant titanium alloy, which specifically comprises the following steps:

[0006] Step 1, fully mix the granular or crumb raw materials for later use;

[0007] Step 2, preparing a consumable electrode according to the product obtained in step 1;

[0008] Step 3, placing the consumable electrode obtained in step 2 in a vacuum consumable arc furnace for smelting to prepare a titanium alloy ingot;

[0009] Step 4, forging the titanium alloy ingot obtained in step 3 to obtain a finished forging blank.

[0010] The present invention is also characterized in that:

[0011] The raw materials in step 1 include sponge titanium, sponge zirconium, pure Al, WAl, TaAl, TiSn, MoAl, TiSi, and NbTi, wherein the Ta content in the TaAl alloy is 55-65%, and the particle size is controlled at 0.05 mm-0.8 mm; the W content in the alloy WAl ​​is 50%-55%, and the particle size is controlled at 0.1 mm-3.0 mm.

[0012] The specific process of step 2 is: when pressing the electrode block, first fill 1 / 2 of the raw material mixed in step 1, then evenly arrange the flaky graphite powder on the already filled 1 / 2 raw material, and then continue to fill the remaining 1 / 2 of the mixed raw material, and finally press it into an electrode block and then weld it to obtain a consumable electrode.

[0013] In step 3, the melting process in the vacuum consumable arc furnace is performed three times.

[0014] The specific process of the third melting in the vacuum consumable arc furnace in step 3 is as follows:

[0015] Step A) loading the consumable electrode after the second smelting into a copper crucible with an inflatable device, and keeping the distance between the electrode and the crucible between 30 mm and 50 mm, sealing the furnace and evacuating the vacuum, and starting smelting after the vacuum degree remains stable at ≤5 Pa;

[0016] Step B), when the weight of the consumable electrode is reduced to 90% to 80% of the original weight, the charging device is turned on, and the inert gas is charged, and the inert gas is continuously charged until the smelting is completed to obtain a finished ingot.

[0017] In the ingot prepared in Step 3, the chemical components and their weight percentages are as follows: Al: 5.5% - 6.5%, Sn: 2.5% - 4.5%, Zr: 3.0% - 4.5%, Mo: 0.1% - 0.8%, Nb: 0.1% - 0.8%, Ta: 1.0% - 3.5%, W: 1.62% - 4.00%, Si: 0.1% - 0.5%, C: 0.03 - 0.1%, O ≤ 0.14%, and the rest is Ti and impurity elements.

[0018] The specific process of Step 4 is as follows:

[0019] Step 4.1: Heat the titanium alloy ingot to 1150°C - 1200°C, hold for 8h - 50h for high-temperature homogenization, then take it out of the furnace and wrap it with asbestos, then put it back into the furnace and hold for 0.5h - 2h, and then take it out of the furnace to complete two upsetting and drawing-forging operations. The final forging temperature of the billet ≥ 820°C;

[0020] Step 4.2: Directly put the billet obtained in Step 4.1 back into the furnace for heating. The heating temperature is 1100°C - 1150°C, hold for 0.5h - 3h, then take it out of the furnace for forging, and complete two upsetting and drawing-forging operations. The requirements for the number of deformation passes and the deformation amount are the same as those in Step 4.1. The final forging temperature of the billet ≥ 800°C. After the forging of the billet is completed, it is air-cooled, and the surface cracks are removed by grinding;

[0021] Step 4.3: Heat the billet obtained in Step 4.2 to 990°C - 1020°C, hold for 6h - 12h and then take it out of the furnace, wrap it with asbestos and then put it back into the furnace and hold for 0.5h - 2h, and then take it out of the furnace to complete one upsetting and drawing-forging operation. The upsetting is completed in 2 - 3 deformation passes. The final forging temperature of the billet needs to ≥ 750°C;

[0022] Step 4.4: Directly put the billet obtained in Step 4.3 back into the furnace for heating. The heating temperature is 990°C - 1020°C, hold for 0.5h - 3h, then take it out of the furnace for forging, and complete one upsetting and drawing-forging operation. The requirements for the number of deformation passes and the deformation amount are the same as those in Step 4.3. The final forging temperature of the billet needs to ≥ 750°C;

[0023] Step 4.5: Directly put the billet obtained in Step 4.4 back into the furnace for heating. The heating temperature is 1070°C - 1100°C. After the billet is taken out of the furnace, wrap asbestos at the end, and then take it out of the furnace to complete one upsetting and drawing-forging operation. The requirements for the number of deformation passes and the deformation amount are the same as those in Step 4.3. The final forging temperature of the billet needs to ≥ 800°C. After the forging of the billet is completed, it is air-cooled, and the surface cracks are removed by grinding;

[0024] Step 4.6: Repeat the processing of the billet obtained in Step 4.5 according to Step 4.3 once;

[0025] Step 4.7: Repeat the processing of the billet obtained in Step 4.6 according to Step 4.4 once;

[0026] Step 4.8, repeat the processing of the blank obtained in Step 4.7 once according to Step 4.5;

[0027] Step 4.9, heat the blank obtained in Step 4.8 to 990°C - 1020°C, keep it warm for 7h - 13h and then take it out of the furnace. After wrapping it with asbestos, continue to put it back into the furnace for heat preservation for 0.5h - 2h, and then take it out of the furnace to complete one upset forging. The final forging temperature of the blank ≥ 750°C;

[0028] Step 4.10, directly put the blank obtained in Step 4.9 back into the furnace for heating, the heating temperature is 990°C - 1020°C, keep it warm for 0.5h - 3h, and then take it out of the furnace for forging to complete one upset forging. The final forging temperature ≥ 750°C. After forging, air cool it to obtain the finished forged blank.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. In response to the development needs of 650°C titanium alloy, the present invention designs a high-temperature titanium alloy of Ti-Al-Mo-Sn-Ta-Zr-W-Nb-Si-C-O system by adding elements such as Ta, Nb, W, C, Si, O, etc. to the alloy. Most of the Ta element is dissolved in the α phase, and the content of the generated β phase is very small, which plays a good solution strengthening role and keeps the solid solution with high plasticity; the addition of W element is beneficial to improving the room temperature strength, creep rupture strength and creep resistance of the titanium alloy without damaging the thermal stability, especially more obvious at high temperatures.

[0031] 2. The present invention adopts the addition method of intermediate alloys such as AlW and AlTa with low melting points to replace the addition method of conventional refractory metals of single W and Ta, so that W and Ta elements can be quickly dissolved during the vacuum consumable melting process; and an inert gas cooling method is adopted during the vacuum consumable melting process to control the melting rate and the solidification rate of the ingot, preventing a large number of fine spherical grains from appearing in the middle position during the solidification process of the ingot due to the too deep molten pool depth, resulting in the aggregation of W and Ta elements at the grain boundaries of these large numbers of fine spherical grains, forming microsegregation.

[0032] 3. The chemical composition uniformity of the ingot obtained by the method provided by the present invention can reach: the range of Al, Sn, Zr, Mo, Nb, Ta, W elements ≤ 2000 ppm, the range of Si element ≤ 500 ppm, and the range of C, O elements ≤ 200 ppm. The obtained forged blank is subjected to solution aging heat treatment. The tensile strength at 650°C is greater than about 620 MPa. Under the stress conditions of 650°C and 260 MPa, the creep rupture performance is greater than 100 h. Under the conditions of 650°C, 100 MPa and 100 h, the creep performance has a residual deformation of less than 0.2%. It meets the industrial production of 650°C high-temperature titanium alloy. Detailed Embodiments

[0033] The present invention will be described in detail below in conjunction with specific embodiments.

[0034] The processing and manufacturing method of the high-temperature titanium alloy of the present invention includes the following steps:

[0035] S1. Granular or chipped raw materials: sponge titanium, sponge zirconium, pure Al, WAl, TaAl, TiSn, MoAl, TiSi, NbTi are fully mixed and then reserved. The Ta content in the TaAl alloy is 55-65%, and the particle size is controlled within 0.05 mm - 0.8 mm; the W content in the alloy WAl is 50% - 55%, and the particle size is controlled within 0.1 mm - 3.0 mm;

[0036] S2. When pressing the electrode block, first fill 1 / 2 of the mixed raw materials, then evenly arrange the high-purity flaky graphite powder on the raw materials, continue to fill the remaining 1 / 2 of the raw materials, and press them into an electrode block and then weld it;

[0037] S3. The consumable electrode is placed in a vacuum consumable arc furnace for three times of melting to make a titanium alloy ingot.

[0038] S4. During the third melting, the consumable electrode is loaded into a copper crucible with an air inflation device, and the distance between the electrode and the crucible is kept between 30 mm and 50 mm. After sealing the furnace, evacuate to a vacuum degree of ≤5 Pa and stably maintain it for 5 minutes before starting the melting. When the weight of the consumable electrode is reduced to 90% - 80% of the original weight, turn on the air inflation device, fill in the inert gas, and keep the inert gas continuously filled until the melting is completed to obtain the finished ingot.

[0039] S5. The chemical composition and weight percentage of the titanium alloy ingot obtained through the above preparation process are: Al: 5.5% - 6.5%, Sn: 2.5% - 4.5%, Zr: 3.0% - 4.5%, Mo: 0.1% - 0.8%, Nb: 0.1% - 0.8%, Ta: 1.0% - 3.5%, W: 1.62% - 4.00%, Si: 0.1% - 0.5%, C: 0.03 - 0.1%, O ≤ 0.14%, and the rest are Ti and inevitable impurity elements. The chemical composition uniformity of the ingot can reach: the range difference of Al, Sn, Zr, Mo, Nb, Ta, W elements ≤ 2000 ppm, the range difference of Si element ≤ 500 ppm, and the range difference of C, O elements ≤ 200 ppm.

[0040] S6. Forge the high-uniformity titanium alloy ingot obtained by the above melting method. First, heat the titanium alloy ingot to 1150°C - 1200°C, hold for 8h - 50h for high-temperature homogenization, then take it out of the furnace and wrap it with asbestos, then put it back into the furnace and hold for 0.5h - 2h, and then take it out of the furnace to complete 2 upsetting and drawing forging operations. The first upsetting is completed in 3 - 5 deformation passes, with the deformation amount per pass controlled at 5% - 8%. The first drawing is completed in 4 - 6 deformation passes, with the deformation amount per pass controlled at 4% - 5%. The second upsetting is completed in 2 - 3 deformation passes, with the deformation amount per pass controlled at 9% - 12%. The second drawing is completed in 4 - 6 deformation passes, with the deformation amount per pass controlled at 4% - 5%. The final forging temperature of the billet needs to be ≥820°C;

[0041] S7. Directly put the billet obtained in S6 back into the furnace for heating, with the heating temperature of 1100°C - 1150°C, hold for 0.5h - 3h, then take it out of the furnace for forging, and complete 2 upsetting and drawing forging operations. The requirements for the number of deformation passes and the deformation amount are the same as those in S1. The final forging temperature of the billet needs to be ≥800°C. After the billet is forged, it is air-cooled, and the surface cracks are removed by grinding;

[0042] S8. Heat the billet obtained in S7 to 990°C - 1020°C, hold for 6h - 12h and then take it out of the furnace, wrap it with asbestos and then put it back into the furnace and hold for 0.5h - 2h, and then take it out of the furnace to complete 1 upsetting and drawing forging operation. The upsetting is completed in 2 - 3 deformation passes, with the deformation amount per pass controlled at 8% - 12%. The drawing is completed in 6 - 8 deformation passes, with the deformation amount per pass controlled at 3% - 4%. The final forging temperature of the billet needs to be ≥750°C;

[0043] S9. Directly put the billet obtained in S8 back into the furnace for heating, with the heating temperature of 990°C - 1020°C, hold for 0.5h - 3h, then take it out of the furnace for forging, and complete 1 upsetting and drawing forging operation. The requirements for the number of deformation passes and the deformation amount are the same as those in S3. The final forging temperature of the billet needs to be ≥750°C;

[0044] S10. Directly put the billet obtained in S9 back into the furnace for heating, with the heating temperature of 1070°C - 1100°C. The holding time is set according to the cross-sectional dimension D (mm) of the billet × 0.40 min / mm. The allowable deviation between the billet taking-out time and the set holding time is +30 min / -0 min. After the billet is taken out of the furnace, wrap it with asbestos at the end, and then take it out of the furnace to complete 1 upsetting and drawing forging operation. The requirements for the number of deformation passes and the deformation amount are the same as those in S3. The final forging temperature of the billet needs to be ≥800°C. After the billet is forged, it is air-cooled, and the surface cracks are removed by grinding;

[0045] S11. Repeat the processing of the billet obtained in S10 according to S8 once;

[0046] S12. Repeat the processing of the billet obtained in S11 according to S9 once;

[0047] S13, processing the blank obtained in S12 again according to S10;

[0048] S14, heating the billet obtained in S13 to 990°C to 1020°C, keeping the temperature for 7h to 13h, taking it out of the furnace, wrapping it with asbestos and then returning it to the furnace to keep the temperature for 0.5h to 2h, and then taking it out of the furnace to complete one stretching forging. The stretching is completed in 4 to 6 deformation steps, and the deformation amount of each step is controlled at 7% to 12%. The final forging temperature of the billet needs to be ≥750°C;

[0049] S15, the billet obtained in S14 is directly returned to the furnace for heating at a temperature of 990°C to 1020°C, and kept at this temperature for 0.5h to 3h, and then taken out of the furnace for forging to complete one stretching forging. The stretching is completed in 5 to 8 deformation steps, and the deformation amount of each step is controlled at 4% to 8%. The final forging temperature needs to be ≥750°C. After forging, it is air-cooled to obtain a finished forging billet.

[0050] The processing and manufacturing process provided by the present invention can be used to prepare ingots with a specification of Φ280mm to Φ850mm and forging blanks with a thickness of 70mm to 200mm and a unit weight of 500kg to 2000kg. After solution aging heat treatment, the forging blank has a tensile strength of greater than about 620MPa at a temperature of 650°C, a durability of greater than 100h at a stress of 650°C and 260MPa, and a creep performance of less than 0.2% at a residual deformation of less than 0.2% at a temperature of 650°C, 100MPa and 100h.

[0051] The following is an explanation of the specific process:

[0052] Embodiment 1:

[0053] 1) Mix the granular or shaving raw materials, such as titanium sponge, zirconium sponge, pure Al, WAl (W content is 50%), TaAl (Ta content is 55%), TiSn, MoAl, TiSi, NbTi, and set aside; when pressing the electrode block, first fill 1 / 2 of the mixed raw materials, then evenly arrange the high-purity flaky graphite powder on the raw materials, continue to fill the remaining 1 / 2 of the raw materials, press it into an electrode block and then weld it; place the consumable electrode in a vacuum consumable arc furnace for three smeltings. During the third smelting, put the consumable electrode into a copper crucible with an inflator, and keep the distance between the electrode and the crucible at 40mm. After sealing the furnace, evacuate the vacuum, and start smelting after the vacuum degree is ≤5Pa and is kept stable for 5 minutes. When the weight of the consumable electrode is reduced to 90% of the original weight, open the inflator, fill it with inert gas, and keep the inert gas continuously filled until the smelting is completed, and obtain an ingot with a diameter of 440mm and a weight of 750kg.

[0054] 2) The chemical composition and uniformity test results of the obtained titanium alloy ingot are shown in Table 1.

[0055] 3) After removing the oxide scale from the surface of the titanium alloy ingot by machining, forging is carried out. First, the titanium alloy ingot is heated to 1170 °C and held for 8 h for high-temperature homogenization. Then it is taken out of the furnace and wrapped with asbestos, and then returned to the furnace for further holding for 0.5 h. Then it is taken out of the furnace to complete 2 upsetting and drawing-forging operations. The first upsetting is completed in 3 deformation passes, with the deformation amount controlled at 5% for each pass. The first drawing is completed in 4 deformation passes, with the deformation amount controlled at 4% for each pass. The second upsetting is completed in 2 deformation passes, with the deformation amount controlled at 9% for each pass. The second drawing is completed in 4 deformation passes, with the deformation amount controlled at 4% for each pass. The final forging temperature of the blank needs to be ≥820 °C;

[0056] 4) The blank obtained in step 3) is directly returned to the furnace for heating at a heating temperature of 1100 °C and held for 0.5 h. Then it is taken out of the furnace for forging to complete 2 upsetting and drawing-forging operations. The requirements for the deformation passes and deformation amount are the same as those in step 3). The final forging temperature of the blank needs to be ≥800 °C. After the blank is forged, it is air-cooled and the surface cracks are removed by grinding;

[0057] 5) The blank obtained in step 4) is heated to 990 °C, held for 6 h and then taken out of the furnace. After wrapping with asbestos, it is returned to the furnace for further holding for 0.5 h. Then it is taken out of the furnace to complete 1 upsetting and drawing-forging operation. The upsetting is completed in 2 deformation passes, with the deformation amount controlled at 8% for each pass. The drawing is completed in 6 deformation passes, with the deformation amount controlled at 3% for each pass. The final forging temperature of the blank needs to be ≥750 °C;

[0058] 6) The blank obtained in step 5) is directly returned to the furnace for heating at a heating temperature of 990 °C and held for 0.5 h. Then it is taken out of the furnace for forging to complete 1 upsetting and drawing-forging operation. The requirements for the deformation passes and deformation amount are the same as those in step 5). The final forging temperature of the blank needs to be ≥750 °C;

[0059] 7) The blank obtained in step 6) is directly returned to the furnace for heating at a heating temperature of 1070 °C, and the holding time is set to 180 - 210 min. After the blank is taken out of the furnace, asbestos is wrapped at the end, and then it is taken out of the furnace to complete 1 upsetting and drawing-forging operation. The requirements for the deformation passes and deformation amount are the same as those in step 5). The final forging temperature of the blank needs to be ≥800 °C. After the blank is forged, it is air-cooled and the surface cracks are removed by grinding;

[0060] 8) The blank obtained in step 7) is processed again according to step 5);

[0061] 9) The blank obtained in step 8) is processed again according to step 6);

[0062] 10) The blank obtained in step 9) is processed again according to step 7);

[0063] 11) The blank obtained in step 10) is heated to 990°C, kept at this temperature for 7 hours, and then taken out of the furnace. After being wrapped with asbestos, it is returned to the furnace and kept at this temperature for 0.5 hours. Then, it is taken out of the furnace to complete one stretching forging. The stretching is completed in 4 steps, and the deformation amount of each step is controlled at 7%. The final forging temperature of the blank needs to be ≥750°C;

[0064] 12) The billet obtained in step 11) is directly returned to the furnace for heating at 990°C for 0.5h, and then taken out of the furnace for forging to complete one stretching forging. The stretching is completed in 5 deformation steps, and the deformation amount of each step is controlled at 4%. The final forging temperature needs to be ≥750°C. After forging, it is air-cooled to obtain a forging billet with a thickness of 70mm and a single weight of 500kg.

[0065] 13) The forging blank obtained in step 12) is subjected to solution aging heat treatment. The room temperature tensile properties are shown in Table 2, and the 650°C tensile, rupture and creep properties are shown in Tables 3 to 5.

[0066] Embodiment 2:

[0067] 1) Mix the raw materials in granular or shaving form, such as titanium sponge, zirconium sponge, pure Al, WAl (W content is 55%), TaAl (Ta content is 65%), TiSn, MoAl, TiSi, NbTi, and set aside; when pressing the electrode block, first fill 1 / 2 of the mixed raw materials, then evenly arrange the high-purity flake graphite powder on the raw materials, continue to fill the remaining 1 / 2 of the raw materials, press it into an electrode block and then weld it; place the consumable electrode in a vacuum consumable arc furnace for three smeltings, during the third smelting, put the consumable electrode into a copper crucible with an inflator, and keep the distance between the electrode and the crucible at 40mm, seal the furnace and evacuate, and start smelting after the vacuum degree is ≤5Pa and is kept stable for 5min. When the weight of the consumable electrode is reduced to 90% of the original weight, open the inflator, fill it with inert gas, and keep the inert gas continuously filled until the smelting is completed, and obtain an ingot with a diameter of 520mm and a weight of 1200kg.

[0068] 2) The chemical composition and uniformity test results of the obtained titanium alloy ingot are shown in Table 1.

[0069] 3) After the titanium alloy ingot is machined to remove the oxide scale from the surface, it is forged. First, the titanium alloy ingot is heated to 1170°C and kept warm for 25 hours for high-temperature homogenization. Then it is taken out of the furnace and wrapped with asbestos. It is then returned to the furnace and kept warm for 1 hour. Then it is taken out of the furnace to complete two rounds of upsetting and drawing forging. The first upsetting is completed in 4 deformation passes, and the deformation amount of each pass is controlled at 6%. The first drawing is completed in 5 deformation passes, and the deformation amount of each pass is controlled at 4.5%. The second upsetting is completed in 2 deformation passes, and the deformation amount of each pass is controlled at 10%. The second drawing is completed in 5 deformation passes, and the deformation amount of each pass is controlled at 4.5%. The final forging temperature of the billet needs to be ≥820°C.

[0070] 4) Heat the blank obtained in step 3) directly in the furnace, with the heating temperature being 1120 °C, hold for 1 h, then take it out of the furnace for forging, complete 2 upsetting and drawing out forging operations. The requirements for the number of deformation passes and the amount of deformation are the same as those in step 3). The final forging temperature of the blank needs to be ≥ 800 °C. After forging, the blank is air-cooled, and the surface cracks are removed by grinding.

[0071] 5) Heat the blank obtained in step 4) to 1000 °C, hold for 6 h and then take it out of the furnace. After wrapping it with asbestos, continue to hold it in the furnace for 1 h, then take it out of the furnace to complete 1 upsetting and drawing out forging operation. The upsetting is completed in 2 deformation passes, with the deformation amount controlled at 10% for each pass. The drawing out is completed in 7 deformation passes, with the deformation amount controlled at 3.5% for each pass. The final forging temperature of the blank needs to be ≥ 750 °C.

[0072] 6) Heat the blank obtained in step 5) directly in the furnace, with the heating temperature being 1000 °C, hold for 1 h, then take it out of the furnace for forging, complete 1 upsetting and drawing out forging operation. The requirements for the number of deformation passes and the amount of deformation are the same as those in step 5). The final forging temperature of the blank needs to be ≥ 750 °C.

[0073] 7) Heat the blank obtained in step 6) directly in the furnace, with the heating temperature being 1080 °C, and set the holding time to 210 - 240 min. After taking the blank out of the furnace, wrap asbestos on the end face, then take it out of the furnace to complete 1 upsetting and drawing out forging operation. The requirements for the number of deformation passes and the amount of deformation are the same as those in step 5). The final forging temperature of the blank needs to be ≥ 800 °C. After forging, the blank is air-cooled, and the surface cracks are removed by grinding.

[0074] 8) Repeat the processing of the blank obtained in step 7) once according to step 5).

[0075] 9) Repeat the processing of the blank obtained in step 8) once according to step 6).

[0076] 10) Repeat the processing of the blank obtained in step 9) once according to step 7).

[0077] 11) Heat the blank obtained in step 10) to 1000 °C, hold for 7 h and then take it out of the furnace. After wrapping it with asbestos, continue to hold it in the furnace for 1 h, then take it out of the furnace to complete 1 drawing out forging operation. The drawing out is completed in 5 deformation passes, with the deformation amount controlled at 10% for each pass. The final forging temperature of the blank needs to be ≥ 750 °C.

[0078] 12) Heat the blank obtained in step 11) directly in the furnace, with the heating temperature being 1000 °C, hold for 1.5 h, then take it out of the furnace for forging, complete 1 drawing out forging operation. The drawing out is completed in 6 deformation passes, with the deformation amount controlled at 6% for each pass. The final forging temperature needs to be ≥ 750 °C. After forging, the blank is air-cooled to obtain a forged blank with a thickness of 120 mm and a single weight of 900 kg.

[0079] 13) The forged billet obtained in step 12) is subjected to solution aging heat treatment. The room temperature tensile properties are shown in Table 2, and the tensile, creep rupture and creep properties at 650 °C are shown in Tables 3 - 5.

[0080] Example 3

[0081] 1) Granular or flaky raw materials, such as: sponge titanium, sponge zirconium, pure Al, WAl (W content is 55%), TaAl (Ta content is 65%), TiSn, MoAl, TiSi, NbTi, are fully mixed and then reserved. When pressing the electrode block, first fill 1 / 2 of the mixed raw materials, then evenly distribute high-purity flaky graphite powder on the raw materials, continue to fill the remaining 1 / 2 of the raw materials, and press them into an electrode block and then weld. The consumable electrode is placed in a vacuum consumable arc furnace for three times of melting. During the third melting, the consumable electrode is loaded into a copper crucible with an air inflation device, and the distance between the electrode and the crucible is kept at 40 mm. After sealing the furnace, evacuate to a vacuum degree ≤ 5 Pa and stably maintain it for 5 min before starting melting. When the weight of the consumable electrode is reduced to 90% of the original weight, turn on the air inflation device, fill in inert gas, and keep the inert gas continuously filled until the melting is completed, obtaining an ingot with a diameter of 720 mm and a weight of 2800 kg.

[0082] 2) The chemical composition and uniformity inspection results of the obtained titanium alloy ingot are shown in Table 1.

[0083] 3) The titanium alloy ingot is machined to remove the oxide scale on the surface and then subjected to forging. First, heat the titanium alloy ingot to 1170 °C and hold for 50 h for high-temperature homogenization, then take it out of the furnace and wrap it with asbestos, then put it back into the furnace and hold for 2 h, and then take it out of the furnace to complete 2 times of upsetting and drawing forging. The first upsetting is completed in 5 passes of deformation, and the deformation amount per pass is controlled at 8%. The first drawing is completed in 6 passes of deformation, and the deformation amount per pass is controlled at 5%. The second upsetting is completed in 3 passes of deformation, and the deformation amount per pass is controlled at 12%. The second drawing is completed in 6 passes of deformation, and the deformation amount per pass is controlled at 5%. The final forging temperature of the billet needs to be ≥ 820 °C;

[0084] 4) The billet obtained in step 3) is directly put back into the furnace for heating, the heating temperature is 1120 °C, hold for 1 h, then take it out of the furnace for forging, complete 2 times of upsetting and drawing forging. The requirements for the number of deformation passes and the deformation amount are the same as those in step 3). The final forging temperature of the billet needs to be ≥ 800 °C. After the billet forging is completed, it is air-cooled and the surface cracks are removed by grinding;

[0085] 5) Heat the blank obtained in step 4) to 1000 °C, keep it warm for 12 h and then take it out of the furnace. After wrapping it with asbestos, put it back into the furnace and keep it warm for another 2 h, and then take it out of the furnace to complete one upsetting and drawing-forging process. The upsetting is completed in 3 deformation passes, with the deformation amount controlled at 12% for each pass. The drawing is completed in 8 deformation passes, with the deformation amount controlled at 4% for each pass. The final forging temperature of the blank needs to be ≥750 °C;

[0086] 6) Directly put the blank obtained in step 5) back into the furnace for heating, with the heating temperature of 1000 °C, keep it warm for 3 h, and then take it out of the furnace for forging to complete one upsetting and drawing-forging process. The requirements for the number of deformation passes and the deformation amount are the same as those in step 5). The final forging temperature of the blank needs to be ≥750 °C;

[0087] 7) Directly put the blank obtained in step 6) back into the furnace for heating, with the heating temperature of 1080 °C and the holding time set at 290 - 320 min. After the blank is taken out of the furnace, wrap asbestos on the end face, and then take it out of the furnace to complete one upsetting and drawing-forging process. The requirements for the number of deformation passes and the deformation amount are the same as those in step 5). The final forging temperature of the blank needs to be ≥800 °C. After the blank is forged, air-cool it and grind to remove the surface cracks;

[0088] 8) Repeat the processing of the blank obtained in step 7) once according to step 5);

[0089] 9) Repeat the processing of the blank obtained in step 8) once according to step 6);

[0090] 10) Repeat the processing of the blank obtained in step 9) once according to step 7);

[0091] 11) Heat the blank obtained in step 10) to 1000 °C, keep it warm for 13 h and then take it out of the furnace. After wrapping it with asbestos, put it back into the furnace and keep it warm for another 2 h, and then take it out of the furnace to complete one drawing-forging process. The drawing is completed in 6 deformation passes, with the deformation amount controlled at 12% for each pass. The final forging temperature of the blank needs to be ≥750 °C;

[0092] 12) Directly put the blank obtained in step 11) back into the furnace for heating, with the heating temperature of 1000 °C, keep it warm for 3 h, and then take it out of the furnace for forging to complete one drawing-forging process. The drawing is completed in 7 deformation passes, with the deformation amount controlled at 6% for each pass. The final forging temperature needs to be ≥750 °C. After forging, air-cool it to obtain a forged blank with a thickness of 200 mm and a single weight of 2000 kg.

[0093] 13) Conduct solution aging heat treatment on the forged blank obtained in step 12). The room temperature tensile properties are shown in Table 2, and the tensile, creep rupture and creep properties at 650 °C are shown in Tables 3 - 5.

[0094] Table 1. Chemical composition of titanium alloy ingot (wt.%)

[0095]

[0096]

[0097] Table 2. Room temperature tensile properties of titanium alloy forging blanks

[0098]

[0099]

[0100] Table 3. 650°C tensile properties of titanium alloy forging blanks

[0101]

[0102] Table 4. 650°C creep rupture properties of titanium alloy forging blanks

[0103]

[0104]

[0105] Table 5. 650°C creep properties of titanium alloy forging blanks

[0106]

[0107] The titanium alloy prepared by the process method provided by the present invention belongs to a high-temperature titanium alloy that can be used for a long time at a temperature of 650°C. By optimizing the preparation process, the problems of compositional uniformity of high-melting-point elements W, Ta, Nb, segregation-prone element Mo, and volatile elements Al, Sn in the ingot of the high-temperature titanium alloy are solved, and the problem of difficult control of the microstructure uniformity of the high-temperature titanium alloy is solved. The high-temperature titanium alloy forging blank prepared by the present invention has high thermal strength and good thermal stability, and can meet the requirements of industrial mass production and use.

Claims

1. Processing and manufacturing method of heat-strengthened titanium alloy, characterized in that, specifically includes the following steps: Step 1, fully mix granular or chipped raw materials and then set aside; the raw materials in Step 1 include sponge titanium, sponge zirconium, pure Al, WAl, TaAl, TiSn, MoAl, TiSi, NbTi, wherein, the Ta content in TaAl alloy is 55% - 65%, and the particle size is controlled within 0.05mm - 0.8mm; the W content in alloy WAl is 50% - 55%, and the particle size is controlled within 0.1mm - 3.0mm; Step 2, make a consumable electrode according to the product obtained in Step 1; the specific process of Step 2 is: when pressing the electrode block, first fill 1 / 2 of the raw materials after mixing in Step 1, then evenly arrange flaky graphite powder on the 1 / 2 of the filled raw materials, and then continue to fill the remaining 1 / 2 of the mixed raw materials, and finally press into an electrode block and weld to obtain a consumable electrode; Step 3, place the consumable electrode obtained in Step 2 in a vacuum consumable arc furnace for melting to make a titanium alloy ingot; the number of melting times in the vacuum consumable arc furnace in Step 3 is three; the specific process of the third melting in the vacuum consumable arc furnace in Step 3 is as follows: Step A) Load the consumable electrode after the second melting into a copper crucible with an air filling device, and keep the distance between the electrode and the crucible within 30mm - 50mm, evacuate the furnace after sealing, and start melting after the vacuum degree ≤ 5Pa remains stable; Step B), when the weight of the consumable electrode reduces to 90% - 80% of the original weight, turn on the air filling device, fill in inert gas, and keep the inert gas continuously filled until the melting is completed to obtain a finished ingot; In the ingot prepared in Step 3, the chemical composition and weight percentage are: Al: 5.5% - 6.5%, Sn: 2.5% - 4.5%, Zr: 3.0% - 4.5%, Mo: 0.1% - 0.8%, Nb: 0.1% - 0.8%, Ta: 1.0% - 3.5%, W: 2.01% - 4.0%, Si: 0.1% - 0.5%, C: 0.03 - 0.1%, O ≤ 0.14%, and the rest are Ti and impurity elements; Step 4, perform forging processing on the titanium alloy ingot obtained in Step 3 to obtain a finished forged blank; the specific process of Step 4 is: Step 4.1, heat the titanium alloy ingot to 1150°C - 1200°C, keep it warm for 8h - 50h for high-temperature homogenization, then take it out of the furnace and wrap it with asbestos, then continue to return to the furnace and keep it warm for 0.5h - 2h, and then take it out of the furnace to complete 2 times of upsetting and drawing forging, and the final forging temperature of the blank ≥ 820°C; Step 4.2, directly return the blank obtained in Step 4.1 to the furnace for heating, the heating temperature is 1100°C - 1150°C, keep it warm for 0.5h - 3h, then take it out of the furnace for forging, complete 2 times of upsetting and drawing forging, and the requirements for the number of deformation passes and deformation amount are the same as those in Step 4.1, the final forging temperature of the blank ≥ 800°C, and the blank is air-cooled after forging and the surface cracks are removed by grinding; Step 4.3: Heat the blank obtained in Step 4.2 to 990°C - 1020°C, keep it warm for 6h - 12h and then take it out of the furnace. After wrapping it with asbestos, put it back into the furnace and keep it warm for 0.5h - 2h, and then take it out of the furnace to complete one upsetting and drawing out forging. The upsetting is completed in 2 - 3 deformation passes, and the final forging temperature of the blank needs to be ≥750°C; Step 4.4: Directly put the blank obtained in Step 4.3 back into the furnace for heating, with the heating temperature of 990°C - 1020°C, keep it warm for 0.5h - 3h, and then take it out of the furnace for forging to complete one upsetting and drawing out forging. The requirements for the number of deformation passes and the amount of deformation are the same as those in Step 4.3, and the final forging temperature of the blank needs to be ≥750°C; Step 4.5: Directly put the blank obtained in Step 4.4 back into the furnace for heating, with the heating temperature of 1070°C - 1100°C. After the blank is taken out of the furnace, wrap asbestos on the end face, and then take it out of the furnace to complete one upsetting and drawing out forging. The requirements for the number of deformation passes and the amount of deformation are the same as those in Step 4.3, and the final forging temperature of the blank needs to be ≥800°C. After the forging of the blank is completed, air cool it and grind to remove the surface cracks; Step 4.6: Repeat the processing of the blank obtained in Step 4.5 according to Step 4.3 once; Step 4.7: Repeat the processing of the blank obtained in Step 4.6 according to Step 4.4 once; Step 4.8: Repeat the processing of the blank obtained in Step 4.7 according to Step 4.5 once; Step 4.9: Heat the blank obtained in Step 4.8 to 990°C - 1020°C, keep it warm for 7h - 13h and then take it out of the furnace. After wrapping it with asbestos, put it back into the furnace and keep it warm for 0.5h - 2h, and then take it out of the furnace to complete one drawing out forging, and the final forging temperature of the blank ≥750°C; Step 4.10: Directly put the blank obtained in Step 4.9 back into the furnace for heating, with the heating temperature of 990°C - 1020°C, keep it warm for 0.5h - 3h, and then take it out of the furnace for forging to complete one drawing out forging, with the final forging temperature ≥750°C. After the forging is completed, air cool it to obtain the finished forged blank.

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