Rolling method of high-uniformity Ti650 high-temperature titanium alloy sheet

Abstract

The invention discloses a rolling method for a high-uniformity Ti650 high-temperature titanium alloy sheet. The rolling method comprises the steps that S1, a Ti650 alloy ingot is subjected to cogging forging and circulating forging; s2, after a pure titanium plate is welded to the surface of the obtained intermediate forging blank, heating and heat preservation are conducted, and a first semi-finished plate blank is obtained through first-fire rolling; s3, the first semi-finished plate blank is subjected to edge cutting, saw cutting, heating, heat preservation and secondary fire rolling, and a second semi-finished plate blank is obtained; s4, the second semi-finished plate blank is subjected to grinding, edge cutting and saw cutting, then heating and heat preservation are conducted, and third-fire rolling is conducted to obtain a third semi-finished plate blank; s5, the third semi-finished product plate blank is subjected to water cutting sizing and pre-oxidation annealing, and a ply rolling bag is manufactured; and S6, the ply rolling bag is heated, subjected to heat preservation and subjected to fourth fire rolling, and the Ti650 high-temperature titanium alloy plate is obtained after treatment. According to the rolling method of the high-uniformity Ti650 high-temperature titanium alloy sheet, the problems that Ti650 alloy is prone to being damaged, the structure performance is not uniform, and the process is complex are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium and titanium alloy rolling, and relates to a rolling method for a high-uniform Ti650 high-temperature titanium alloy thin plate. Background Art

[0002] At present, the long-term use temperature requirement of high-thrust-to-weight ratio aircraft engines for high-temperature titanium alloys is higher than 600℃, so 650℃ high-temperature titanium alloys have become the key development direction in the future. Ti650 titanium alloy belongs to the Ti-Al-Sn-Zr-Mo-Si-Nb-Ta-WC series multi-solution strengthened 650℃ near-α-type high-temperature titanium alloy, which has the characteristics of low density, high specific strength and good high-temperature performance. It can serve for a long time in a 650℃ working environment. It is mainly used to manufacture key components such as integral blades, blades, high Mach aircraft skins and hot end components of aircraft engine compressors, and can meet the use needs of my country's high thrust-to-weight ratio, low energy consumption turbofan and turboshaft engines.

[0003] The alloy has an Al equivalent of 7.8 and a β stability coefficient Kβ of up to 0.55. In addition to being affected by alloying elements, grain size, organizational morphology and α phase size content, the alloy's mechanical properties are also relatively greatly affected by the uniformity of texture distribution. As a near-α-type high-temperature titanium alloy dominated by close-packed hexagonal α phase, the alloy has difficulty in plastic deformation due to the small number of independent slip systems in the close-packed hexagonal α phase. In addition, Ti650 alloy sheets are more likely to produce strong deformation textures and anisotropy, which have an important impact on the performance of the material.

[0004] Due to the narrow hot working window and poor processability of Ti650 alloy materials, the rolling process has high deformation resistance, easy to cause damage, and the difficulty of controlling the uniformity of organizational properties. At present, high-temperature titanium alloy plates generally adopt the method of "forging above the phase transition point to obtain the intermediate billet, rolling at a high temperature in one fire, and then rolling at a lower temperature in the next fire". The different specifications of the finished products lead to inconsistent rolling procedures, which is not conducive to mass production. Moreover, when the thickness of the titanium alloy plate is less than 10mm, the temperature drops quickly during the rolling process, and frequent reheating is required, resulting in extremely low production efficiency. The slabs in the stacking rolling process need to be isolated with special coatings, and the process stability is poor. Summary of the invention

[0005] The purpose of the present invention is to provide a rolling method for a high-uniform Ti650 high-temperature titanium alloy thin plate, which adopts two-phase temperature forging to obtain an intermediate billet, welds a layer of pure titanium plate on its surface, and then uses a steel ladle process to roll it to a finished product size. All rolling processes are always carried out at the same temperature, thereby solving the problems of easy damage to the Ti650 alloy, uneven organizational properties, complex process and difficult production scheduling.

[0006] The technical solution adopted by the present invention is a rolling method for a high-uniform Ti650 high-temperature titanium alloy sheet, and the specific steps are as follows: Step 1, subjecting the Ti650 alloy ingot to two-fire blank forging and multi-fire cycle forging to obtain an intermediate forging blank; Step 2, after 100% grinding of the intermediate forging blank, a layer of 1-2 mm pure titanium plate is welded on the upper surface and the lower surface thereof, and the first heating and heat preservation is performed, followed by a first hot rolling to obtain the first semi-finished slab; Step 3, removing the edge defects of the first semi-finished slab, sawing it along its length direction, heating and heat preservation for the second time, and then performing double-heat rolling to obtain a second semi-finished slab; Step 4, the second semi-finished slab is 100% polished, the edge defects are removed, and the slab is sawn and cut into pieces, and then heated and kept warm for the third time, and then three-fire rolling is performed in a continuous tempering manner to obtain a third semi-finished slab; Step 5, after straightening the third semi-finished slab, 100% polishing and removing edge defects are performed, and water jet cutting is used to cut the length and pre-oxidation annealing is performed, and then the annealed multi-layered third semi-finished slab is welded with steel plates and steel bars to form a stacked rolling package; Step 6, heating and heat-insulating the stacked rolling package for the fourth time, and then performing the fourth hot rolling, and then stress relief annealing, stacked rolling package rough sizing, straightening, unpacking, surface sanding and sizing to obtain Ti650 high-temperature titanium alloy plate, the thickness of the Ti650 high-temperature titanium alloy plate is 0.7mm~2.0mm.

[0007] The present invention is also characterized in that: In step 1, the billet forging is carried out at 80°C to 150°C above the phase transformation point temperature for 400 to 600 minutes, the final forging temperature is not less than 850°C, and air cooling is performed after breaking.

[0008] In step 1, the Ti650 alloy ingot after 2-time blank forging is 100% polished and then cyclic forging is performed. The cyclic forging adopts a "low and high" cyclic forging method, wherein the low temperature forging temperature is 30°C to 60°C below the phase transition point temperature, and the high temperature forging temperature is 30°C to 80°C above the phase transition point temperature. The heating and holding time of each low temperature forging or high temperature forging is a*Dmin, wherein a is 0.75 to 0.90, in units of min / mm, and D is the thickness of the forging blank, in units of mm. 4 to 6 fires are repeatedly forged, and the final forging temperature is not less than 800°C.

[0009] The temperature of the first heating and insulation in step 2 is 40°C to 80°C below the phase transition point temperature, the time is 2 to 4 hours, and the final rolling temperature is not less than 800°C; The deformation of one hot rolling pass is 5%~15%, the number of passes is 5~10, the rolling rate is 2m / s~5m / s, and the deformation of one hot rolling pass is 45%~65%; the rolling direction of one hot rolling is longitudinal rolling.

[0010] Step 3: The temperature of the second heating and insulation is 40°C to 80°C below the phase transition point, the time is 1.5 to 3 hours, and the final rolling temperature is not less than 800°C; The deformation of the second-pass rolling is 7%~20%, the number of passes is 5~10, the rolling rate is 2m / s~5m / s, and the deformation of the second pass is 45%~70%; the second-pass rolling direction is along the width.

[0011] The temperature of the third heating and insulation in step 4 is 40°C to 80°C below the phase transition point temperature, and the time is 1.5 to 2 hours. When the rolling temperature is lower than 800°C, the furnace needs to be returned to the furnace for heating once, and the time of the return to the furnace for heating is 40min to 60min. The final rolling temperature is not lower than 750°C. The deformation of three-pass rolling is 7%~20%, the number of passes is 5~10, the rolling speed is 2m / s~5m / s, and the deformation of each pass is 60%~90%; The thickness of the third semi-finished slab does not exceed 6 mm.

[0012] In step 5, the pre-oxidation annealing temperature is 600°C~650°C, and the holding time is 2h.

[0013] The preparation method of the stacked rolling package in step 5 is: stack 2 to 4 layers of the third semi-finished slab in sequence, then weld it around with steel plates and steel bars, and open exhaust holes on the front and rear steel plates. Soft insulation needs to be filled between the steel plates of the stacked rolling package and the stacked slabs.

[0014] The temperature of the fourth heating and insulation in step 6 is 40°C to 80°C below the phase transition point temperature, the time is 1 to 2 hours, and the rolling temperature is not less than 800°C; The deformation of four-pass rolling is 7%~20%, the number of passes is 5~10, the rolling rate is 2m / s~5m / s, and the deformation of each pass is 60%~90%.

[0015] In step 6, the stress relief annealing temperature is 600°C~650°C, and the temperature is kept for 2 hours.

[0016] The beneficial effects of the present invention are: (1) The rolling method of the high-uniform Ti650 high-temperature titanium alloy sheet of the present invention has a first-fire rolling temperature of 40°C to 60°C below the phase transition point, and a two-phase heating and deformation temperature, which improves the problem of uneven microstructure and performance caused by local significant temperature rise caused by severe deformation during conventional high-temperature rolling, while ensuring higher comprehensive mechanical properties; all rolling fires use one heating temperature, which is conducive to continuous production and improves production efficiency; (2) The rolling method of the high-uniform Ti650 high-temperature titanium alloy sheet of the present invention is to weld a layer of pure titanium plate on the upper surface and the lower surface of the intermediate billet before the first-stage rolling, replacing the traditional high-temperature resistant anti-oxidation coating, thereby improving the cracking problem of the material during the billet rolling. No surface treatment is required after the billet rolling, which significantly improves the yield rate and has high stability in the production process; (3) In the rolling method of the high-uniform Ti650 high-temperature titanium alloy sheet of the present invention, the stacked slab is pre-oxidized before the ladle, instead of applying the isolation coating material in the traditional method, which solves the dependence on the isolation coating material and makes the whole production process more stable; (4) The rolling method of the high-uniform Ti650 high-temperature titanium alloy thin plate of the present invention adopts the method of upper and lower cladding steel plates during the heating treatment of the third semi-finished slab with a thickness not exceeding 6 mm, in view of the characteristics of Ti650 titanium alloy being sensitive to temperature, having a narrow processing window, and cooling rapidly during the rolling process after thickness reduction. This ensures the rolling temperature of the Ti650 titanium alloy, reduces the obvious cracking of the titanium alloy caused by temperature drop and the frequent remelting for heating in the traditional process, and also reduces the amount of grinding in the later stage, saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a 200-fold magnified organization diagram of the head of the plate in the rolled state in Example 1 of the present invention; Figure 2 This is a 500-fold magnified organization diagram of the head of the plate rolled in Example 1 of the present invention; Figure 3 This is a 200-fold magnified microstructure diagram of the tail of the plate rolled in Example 1 of the present invention; Figure 4 This is a 500-fold magnified microstructure diagram of the tail of the plate rolled in Example 1 of the present invention; Figure 5 This is a 200-fold magnified organization diagram of the head of the plate rolled in Example 1 of the present invention after heat treatment; Figure 6 This is a 500-fold magnified organization diagram of the head of the plate rolled in Example 1 of the present invention after heat treatment; Figure 7 This is a 200-fold magnified organization diagram of the tail of the plate rolled in Example 1 of the present invention after heat treatment; Figure 8 This is a 500-fold magnified organization diagram of the tail of the plate rolled in Example 1 of the present invention after heat treatment. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] The rolling method of the high-uniform Ti650 high-temperature titanium alloy sheet of the present invention comprises the following specific steps: Step 1, subjecting the Ti650 alloy ingot to two-fire forging and multi-fire cycle forging to obtain an intermediate forging blank; wherein the Ti650 alloy ingot used can be a 5t grade Ti650 alloy ingot with a diameter of Φ690~Φ720mm.

[0020] Specifically, the billet forging is carried out at 80°C to 150°C above the phase transformation point temperature for 400 to 600 minutes, the final forging temperature is not less than 850°C, and air cooling is performed after breaking.

[0021] The Ti650 alloy ingot after 2 rounds of blank forging was 100% polished and then cyclic forging was performed. The cyclic forging adopted a "low and high" cyclic forging method, in which the low temperature forging temperature was 30℃~60℃ below the phase transformation point temperature, and the high temperature forging temperature was 30℃~80℃ above the phase transformation point temperature. The heating and holding time of each low temperature forging or high temperature forging was a*D min, in which a was 0.75~0.90, in min / mm, and D was the thickness of the forging blank in mm. 4~6 rounds of repeated forging were performed, and the final forging temperature was not less than 800℃.

[0022] Step 2, after 100% grinding of the intermediate forging blank, a layer of 1-2 mm pure titanium plate is welded on the upper surface and the lower surface thereof, and the first heating and heat preservation is performed, followed by a first hot rolling to obtain the first semi-finished slab; Among them, the temperature of the first heating and insulation is 40℃~80℃ below the phase transformation point temperature, the time is 2~4h, and the final rolling temperature is not less than 800℃; the deformation of one hot rolling pass is 5%~15%, the number of passes is 5~10, the rolling rate is 2m / s~5m / s, and the deformation of one hot rolling pass is 45%~65%; the rolling direction of one hot rolling is longitudinal rolling.

[0023] Step 3, removing the edge defects of the first semi-finished slab, sawing it along its length direction, heating and heat preservation for the second time, and then performing double-heat rolling to obtain a second semi-finished slab; Among them, the temperature of the second heating and insulation is 40℃~80℃ below the phase transformation point temperature, the time is 1.5~3h, and the final rolling temperature is not less than 800℃; the deformation of the second fire rolling pass is 7%~20%, the number of passes is 5~10, the rolling rate is 2m / s~5m / s, and the deformation of the fire is 45%~70%; the second fire rolling direction is rolling along the width.

[0024] Step 4, the second semi-finished slab is 100% polished, the edge defects are removed, and the slab is sawn and cut into pieces, and then heated and kept warm for the third time, and three-fire rolling is performed in a continuous tempering manner to obtain a third semi-finished slab; Among them, the temperature of the third heating and holding is 40℃~80℃ below the phase transition point temperature, the time is 1.5~2h, when the rolling temperature is lower than 800℃, it needs to be returned to the furnace for heating once, the return time is 40min~60min, and the final rolling temperature is not lower than 750℃; the deformation of the three-pass rolling is 7%~20%, the number of passes is 5~10, the rolling rate is 2m / s~5m / s, and the deformation of the fire is 60%~90%; The thickness of the third semi-finished slab does not exceed 6 mm, and its rolling direction is consistent with the previous rolling direction.

[0025] Step 5, after straightening the third semi-finished slab, perform 100% polishing and remove edge defects, and use water jet cutting to cut length and pre-oxidation annealing, the pre-oxidation annealing temperature is 600℃~650℃, keep warm for 2h, then use steel plates and steel bars to weld the multi-layered third semi-finished slabs after annealing to form a stacked rolling package. The specific method is: stack 2~4 layers of the third semi-finished slab in sequence, and then use steel plates and steel bars to weld them all around, and open exhaust holes on the front and rear steel plates respectively, and soft insulation needs to be filled between the steel plates of the stacked rolling package and the stacked slabs.

[0026] Step 6, heating and heat-insulating the stacked rolling package for the fourth time, and then performing the fourth hot rolling, and then undergoing stress relief annealing, rough sizing of the stacked rolling package, straightening, unpacking, surface sanding and sizing to obtain the Ti650 high-temperature titanium alloy plate, and the thickness of the Ti650 high-temperature titanium alloy plate is 0.7mm~2.0mm.

[0027] Among them, the temperature of the fourth heating and holding is 40℃~80℃ below the phase transition point temperature, the time is 1~2h, and the rolling temperature is not less than 800℃; the deformation of the four-fire rolling pass is 7%~20%, the number of passes is 5~10, the rolling rate is 2m / s~5m / s, and the deformation of the fire is 60%~90%; The stress relief annealing temperature is 600℃~650℃, and the temperature is kept for 2h.

[0028] Example 1 The rolling method of high uniform Ti650 high temperature titanium alloy sheet is specifically implemented according to the following steps: Step 1, a 5t Ti650 alloy ingot with a diameter of Φ690 is subjected to 2 fires of blank forging, the blank forging is heated to 80°C above the phase transition point temperature, kept warm for 600min, the final forging temperature is not less than 850°C, air-cooled after breaking, 100% polished and repaired, and then a "low and high" cycle forging method is adopted, wherein the low temperature forging temperature is 30°C below the phase transition point temperature, and the high temperature forging temperature is 30°C above the phase transition point temperature. The heating and holding time of each low temperature forging or high temperature forging is 150min, and 4 fires are repeated forging, and the final forging temperature is not less than 850°C, to obtain an intermediate forging blank with a size of δ200mm.

[0029] Step 2: After 100% grinding of the intermediate forging billet of δ200mm and welding a layer of 1mm thick pure titanium plate on the upper and lower surfaces, heat to 40°C below the phase transformation point temperature, keep warm for 200min, and perform one-pass rolling. The total number of passes is 8. The deformation of each of the first three passes does not exceed 7%, and the deformation of each of the remaining passes does not exceed 10%. The rolling rate is 2m / s, the deformation of each fire is 50%, the rolling direction is longitudinal rolling, and the final rolling temperature is not less than 850°C to obtain the first semi-finished slab with a size of δ100mm.

[0030] Step 3: Cut off the edge defects of the first semi-finished slab of δ100mm and saw it in the length direction, heat it to 40℃ below the phase change point temperature, keep it warm for 120min, the deformation per pass does not exceed 10%, the number of passes is 7, the rolling rate is 2m / s, the deformation per fire is 65%, the rolling direction is rolling along the width, the final rolling temperature is not less than 850℃, and the second semi-finished slab with a size of δ35mm is obtained.

[0031] Step 4: 100% grind, trim and saw the second semi-finished slab of δ35mm, heat it to 40℃ below the phase change point, keep it warm for 90min, and perform three-pass rolling in a continuous tempering manner. The deformation of each rolling pass is 7%, the number of passes is 6, the rolling rate is 2m / s, the deformation of each fire is 70%, and it is rolled to δ10mm. After the hot material is cut off, it is returned to the furnace for 50min of heating, and rolled for 6 passes after being taken out of the furnace. The final rolling temperature is not less than 750℃ to obtain a third semi-finished slab with a size of δ5mm. Step 5: Straighten, 100% polish, trim, cut to length, and pre-oxidize and anneal at 600℃ / 2h for the third semi-finished slab with a thickness of δ5mm, then weld the 4 layers of the third semi-finished slab with annealing using steel plates and edge-sealing steel bars to form a stacked rolling package with a thickness of δ30mm. Vent holes are opened on the front and rear steel plates.

[0032] Step 6: Heat the δ30 mm thick rolled sheet to 40°C below the phase transition point temperature, keep warm for 90 min, perform the fourth hot rolling, the rolling pass deformation is 7%, the number of passes is 5, the rolling rate is 2 m / s, and the final rolling temperature is not less than 800°C to obtain a fourth semi-finished slab with a size of δ12 mm, and then undergo stress relief annealing at 600°C / 2h, rough sizing, straightening, unpacking, surface sanding and sizing to obtain a Ti650 high-temperature titanium alloy plate with a thickness of δ2.0 mm.

[0033] Example 2 Step 1, a 5t grade Ti650 alloy ingot with a diameter of Φ690 is subjected to 2 fires of blank forging, the blank forging is heated to 150°C above the phase transition point temperature, kept warm for 400min, the final forging temperature is not less than 850°C, air-cooled after breaking, 100% grinding and repairing, and then a "low, high" cycle forging method is adopted, wherein the low temperature forging temperature is 60°C below the phase transition point temperature, and the high temperature forging temperature is 80°C above the phase transition point temperature. The heating and holding time of each low temperature forging or high temperature forging is 180min, and 6 fires are repeatedly forged, and the final forging temperature is not less than 850°C to obtain an intermediate forging blank with a size of δ200mm.

[0034] Step 2: After 100% grinding of the intermediate forging billet of δ200 mm and welding a layer of 1.5 mm thick pure titanium plate on the upper and lower surfaces, heat to 60°C below the phase transformation point temperature, keep warm for 240 minutes, and perform one-pass rolling. The total number of passes is 5, the deformation of each of the first three passes is 5%, and the deformation of each of the remaining passes does not exceed 10%. The rolling rate is 5 m / s, the deformation of each fire is 65%, the rolling direction is longitudinal rolling, and the final rolling temperature is not less than 800°C to obtain the first semi-finished slab with a size of δ100 mm.

[0035] Step 3: Cut off the edge defects of the first semi-finished slab of δ100mm and saw it in the length direction, heat it to 60℃ below the phase change point temperature, keep it warm for 180min, the deformation amount per pass does not exceed 10%, the number of passes is 5, the rolling rate is 5m / s, the deformation amount per fire is 70%, the rolling direction is rolling along the width, the final rolling temperature is not less than 850℃, and the second semi-finished slab with a size of δ36mm is obtained.

[0036] Step 4: 100% grind, trim and saw the second semi-finished slab of δ36mm, heat it to 60℃ below the phase change point, keep it warm for 120min, and perform three-pass rolling in a continuous tempering manner. The deformation of each rolling pass is 7%, the number of passes is 5, the rolling rate is 5m / s, the deformation of each fire is 90%, and the slab is rolled to δ10mm. After the hot material is cut off, return to the furnace for 60min of heating, and roll it out of the furnace for 6 passes. The final rolling temperature is not less than 750℃ to obtain a third semi-finished slab with a size of δ4.5mm. Step 5: Straighten, 100% polish, trim, cut to length, and pre-oxidize and anneal at 650°C / 2h for the third semi-finished slab with a thickness of δ4.5mm, then weld the 3 layers of the annealed third semi-finished slab with steel plates and edge-sealing steel bars to form a stacked rolling package with a thickness of δ25mm. Vent holes are opened on the front and rear steel plates.

[0037] Step 6: Heat the δ25mm thick rolled sheet to 40°C below the phase transition point temperature, keep warm for 120min, and perform the fourth hot rolling, with a rolling pass deformation of 7%, 10 passes, a rolling rate of 5m / s, and a final rolling temperature of not less than 800°C to obtain a fourth semi-finished slab with a size of δ8mm, and then undergo stress relief annealing at 600°C / 2h, rough sizing, straightening, unpacking, surface sanding and sizing to obtain a Ti650 high-temperature titanium alloy plate with a thickness of δ1.2mm.

[0038] Example 3 Step 1, a 5t grade Ti650 alloy ingot with a diameter of Φ690 is subjected to 2 fires of blank forging, the blank forging is heated to 120°C above the phase transition point temperature, kept warm for 500min, the final forging temperature is not less than 850°C, air-cooled after breaking, 100% grinding and repairing, and then a "low, high" cycle forging method is adopted, wherein the low temperature forging temperature is 50°C below the phase transition point temperature, and the high temperature forging temperature is 50°C above the phase transition point temperature. The heating and holding time of each low temperature forging or high temperature forging is 160 min, and 4 fires are repeated forging, and the final forging temperature is not less than 850°C to obtain an intermediate forging blank with a size of δ200mm.

[0039] Step 2: After 100% grinding of the intermediate forging billet of δ200 mm and welding a layer of 2 mm thick pure titanium plate on the upper and lower surfaces, the billet is heated to 80°C below the phase transition point, kept warm for 180 min, and subjected to one-pass rolling. The total number of passes is 10, and the deformation of each of the first three passes does not exceed 8%, and the deformation of each of the remaining passes does not exceed 13%. The rolling rate is 3 m / s, the deformation of each pass is 45%, the rolling direction is longitudinal rolling, and the final rolling temperature is not less than 800°C to obtain the first semi-finished slab with a size of δ105 mm.

[0040] Step 3: Cut off the edge defects of the first semi-finished slab of δ105mm and saw it in the length direction, heat it to 80℃ below the phase change point temperature, keep it warm for 90min, the deformation amount per pass does not exceed 10%, the number of passes is 10, the rolling rate is 3m / s, the deformation amount per fire is 45%, the rolling direction is rolling along the width, the final rolling temperature is not less than 850℃, and a second semi-finished slab with a size of δ40mm is obtained.

[0041] Step 4: 100% grind, trim and saw the second semi-finished slab of δ40mm, heat it to 80℃ below the phase change point, keep it warm for 100min, and perform three-pass rolling in a continuous tempering manner. The deformation of each rolling pass is 18%, the number of passes is 10, the rolling rate is 3m / s, the deformation of each fire is 60%, and it is rolled to δ10mm. After the hot material is cut off, it is returned to the furnace for 40min of heating, and rolled for 6 passes after being taken out of the furnace. The final rolling temperature is not less than 750℃ to obtain a third semi-finished slab with a size of δ4mm. Step 5: Straighten, 100% polish, trim, cut to length, and pre-oxidize and anneal at 630℃ / 2h for the third semi-finished slab with a thickness of δ4mm, then weld the 4 layers of the third semi-finished slab with steel plates and edge-sealing steel bars to form a stacked rolling package with a thickness of δ28mm. Vent holes are opened on the front and rear steel plates.

[0042] Step 6: Heat the δ28mm thick rolled sheet to 80°C below the phase transition point, keep warm for 60min, and perform the fourth hot rolling, with a rolling pass deformation of 16%, 8 passes, a rolling rate of 3m / s, and a final rolling temperature of not less than 800°C to obtain a fourth semi-finished slab with a size of δ8mm, and then perform stress relief annealing at 650°C / 2h, rough sizing, straightening, unpacking, surface sanding and sizing to obtain a Ti650 high-temperature titanium alloy sheet with a thickness of δ1.3mm.

[0043] Example 4 The rolling method of high uniform Ti650 high temperature titanium alloy sheet is specifically implemented according to the following steps: Step 1, a 5t Ti650 alloy ingot with a diameter of Φ690 is subjected to 2 fires of blank forging, the blank forging is heated to 120°C above the phase transition point temperature, kept warm for 600min, the final forging temperature is not less than 850°C, air-cooled after breaking, 100% grinding and repairing, and then a "low, high" cycle forging method is adopted, wherein the low temperature forging temperature is 40°C below the phase transition point temperature, and the high temperature forging temperature is 60°C above the phase transition point temperature. The heating and holding time of each low temperature forging or high temperature forging is 150min, and 6 fires are repeated forging, and the final forging temperature is not less than 850°C to obtain an intermediate forging blank with a size of δ200mm.

[0044] Step 2: After 100% grinding of the intermediate forging billet of δ200 mm and welding a layer of 1 mm thick pure titanium plate on the upper and lower surfaces, heat to 50 ° C below the phase transformation point temperature, keep warm for 120 minutes, and perform one-pass rolling. The total number of passes is 7. The deformation of each of the first three passes does not exceed 7%, and the deformation of each of the remaining passes does not exceed 10%. The rolling rate is 4 m / s, the deformation of each fire is 60%, the rolling direction is longitudinal rolling, and the final rolling temperature is not less than 850 ° C to obtain the first semi-finished slab with a size of δ100 mm.

[0045] Step 3: Cut off the edge defects of the first semi-finished slab of δ100mm and saw it in the length direction, heat it to 70℃ below the phase change point temperature, keep it warm for 100min, the deformation per pass does not exceed 10%, the number of passes is 6, the rolling rate is 4m / s, the deformation per fire is 65%, the rolling direction is rolling along the width, the final rolling temperature is not less than 850℃, and the second semi-finished slab with a size of δ35mm is obtained.

[0046] Step 4: 100% grind, trim and saw the second semi-finished slab of δ35mm, heat it to 70℃ below the phase change point, keep it warm for 110min, and perform three-pass rolling in a continuous tempering manner. The deformation of each rolling pass is 7%, the number of passes is 6, the rolling rate is 4m / s, the deformation of each fire is 70%, and the slab is rolled to δ10mm. After the hot material is cut off, return to the furnace for 50min of heating, and roll it out of the furnace for 6 passes. The final rolling temperature is not less than 750℃ to obtain a third semi-finished slab with a size of δ5mm. Step 5: Straighten, 100% polish, trim, cut to length, and pre-oxidize and anneal at 620℃ / 2h for the third semi-finished slab with a thickness of δ5mm, then weld the two layers of the annealed third semi-finished slab with steel plates and edge-sealing steel bars to form a stacked rolling package with a thickness of δ20mm. Vent holes are opened on the front and rear steel plates.

[0047] Step 6: Heat the δ20 mm thick rolled sheet to 70°C below the phase transition point, keep warm for 100 min, and perform the fourth hot rolling, with a rolling pass deformation of 7%, 7 passes, a rolling rate of 4 m / s, and a final rolling temperature of not less than 800°C to obtain a fourth semi-finished slab with a size of δ12 mm, and then perform stress relief annealing at 630°C / 2h, rough sizing, straightening, unpacking, surface sanding and sizing to obtain a Ti650 high-temperature titanium alloy sheet with a thickness of δ2.0 mm.

[0048] Example 5 The rolling method of high uniform Ti650 high temperature titanium alloy sheet is specifically implemented according to the following steps: Step 1, a 5t Ti650 alloy ingot with a diameter of Φ690 is subjected to 2 fires of blank forging, the blank forging is heated to 90°C above the phase transition point temperature, kept warm for 400min, the final forging temperature is not less than 850°C, air-cooled after breaking, 100% grinding and repairing, and then a "low, high" cycle forging method is adopted, wherein the low temperature forging temperature is 40°C below the phase transition point temperature, and the high temperature forging temperature is 60°C above the phase transition point temperature. The heating and holding time of each low temperature forging or high temperature forging is 170min, and 6 fires are repeatedly forged, and the final forging temperature is not less than 850°C to obtain an intermediate forging blank with a size of δ200mm.

[0049] Step 2: After 100% grinding of the intermediate forging billet of δ200 mm and welding a layer of 1.2 mm thick pure titanium plate on the upper and lower surfaces, heat to 70°C below the phase transformation point temperature, keep warm for 210 minutes, and perform one-pass rolling. The total number of passes is 6. The deformation of each of the first three passes does not exceed 7%, and the deformation of each of the remaining passes does not exceed 10%. The rolling rate is 3m / s, the deformation of each fire is 60%, the rolling direction is longitudinal rolling, and the final rolling temperature is not less than 850°C to obtain the first semi-finished slab with a size of δ100 mm.

[0050] Step 3: Cut off the edge defects of the first semi-finished slab of δ100mm and saw it in the length direction, heat it to 50℃ below the phase change point temperature, keep it warm for 150min, the deformation per pass does not exceed 10%, the number of passes is 6, the rolling rate is 3m / s, the deformation per fire is 65%, the rolling direction is rolling along the width, the final rolling temperature is not less than 850℃, and a second semi-finished slab with a size of δ35mm is obtained.

[0051] Step 4: 100% grind, trim and saw the second semi-finished slab of δ35mm, heat it to 60℃ below the phase change point, keep it warm for 110min, and perform three-pass rolling in a continuous tempering manner. The deformation of each rolling pass is 7%, the number of passes is 6, the rolling rate is 3m / s, the deformation of each fire is 70%, and it is rolled to δ10mm. After the hot material is cut off, it is returned to the furnace for 50min of heating, and rolled for 6 passes after being taken out of the furnace. The final rolling temperature is not less than 750℃ to obtain a third semi-finished slab with a size of δ5mm. Step 5: Straighten, 100% polish, trim, cut to length, and pre-oxidize and anneal at 620℃ / 2h for the third semi-finished slab with a thickness of δ5mm, then weld the two layers of the annealed third semi-finished slab with steel plates and edge-sealing steel bars to form a stacked rolling package with a thickness of δ20mm. Vent holes are opened on the front and rear steel plates.

[0052] Step 6: Heat the δ20 mm thick rolled sheet to 70°C below the phase transition point, keep warm for 100 min, and perform the fourth hot rolling, with a rolling pass deformation of 7%, 7 passes, a rolling rate of 4 m / s, and a final rolling temperature of not less than 800°C to obtain a fourth semi-finished slab with a size of δ12 mm, and then perform stress relief annealing at 630°C / 2h, rough sizing, straightening, unpacking, surface sanding and sizing to obtain a Ti650 high-temperature titanium alloy sheet with a thickness of δ2.0 mm.

[0053] Example 6 Step 1, a 5t grade Ti650 alloy ingot with a diameter of Φ690 is subjected to 2 fires of blank forging, the blank forging is heated to 50°C above the phase transition point temperature, kept warm for 500min, the final forging temperature is not less than 850°C, air-cooled after breaking, 100% grinding and repairing, and then a "low, high" cycle forging method is adopted, wherein the low temperature forging temperature is 55°C below the phase transition point temperature, and the high temperature forging temperature is 70°C above the phase transition point temperature. The heating and holding time of each low temperature forging or high temperature forging is 180min, and 6 fires are repeated forging, and the final forging temperature is not less than 850°C to obtain an intermediate forging blank with a size of δ200mm.

[0054] Step 2: After 100% grinding of the intermediate forging billet of δ200 mm and welding a layer of 1.6 mm thick pure titanium plate on the upper and lower surfaces, heat to 65 ° C below the phase transformation point temperature, keep warm for 190 min, and perform one-pass rolling. The total number of passes is 5, the deformation of each of the first three passes is 5%, and the deformation of each of the remaining passes does not exceed 10%. The rolling rate is 2 m / s, the deformation of each fire is 65%, the rolling direction is longitudinal rolling, and the final rolling temperature is not less than 800 ° C to obtain the first semi-finished slab with a size of δ100 mm.

[0055] Step 3: Cut off the edge defects of the first semi-finished slab of δ100mm and saw it in the length direction, heat it to 60℃ below the phase change point temperature, keep it warm for 170min, the deformation per pass does not exceed 10%, the number of passes is 5, the rolling rate is 2m / s, the deformation per fire is 70%, the rolling direction is rolling along the width, the final rolling temperature is not less than 850℃, and a second semi-finished slab with a size of δ35mm is obtained.

[0056] Step 4: 100% grind, trim and saw the second semi-finished slab of δ35mm, heat it to 55℃ below the phase change point, keep it warm for 115min, and perform three-pass rolling in a continuous tempering manner. The deformation of each rolling pass is 7%, the number of passes is 5, the rolling rate is 2m / s, the deformation of each fire is 90%, and the slab is rolled to δ10mm. After the hot material is cut off, return to the furnace for 60min of heating, and roll it out of the furnace for 6 passes. The final rolling temperature is not less than 750℃ to obtain a third semi-finished slab with a size of δ5mm. Step 5: Straighten, 100% polish, trim, cut to length, and pre-oxidize and anneal at 650℃ / 2h for the third semi-finished slab with a thickness of δ5mm, then weld the 4 layers of the third semi-finished slab after annealing with steel plates and edge-sealing steel bars to form a stacked rolling package with a thickness of δ30mm. Vent holes are opened on the front and rear steel plates.

[0057] Step 6: Heat the δ30mm thick rolled sheet to 40°C below the phase transition point temperature, keep warm for 120min, and perform the fourth hot rolling, with a rolling pass deformation of 7%, 10 passes, a rolling rate of 2m / s, and a final rolling temperature of not less than 800°C to obtain a fourth semi-finished slab with a size of δ8mm, and then perform stress relief annealing at 630°C / 2h, rough sizing, straightening, unpacking, surface sanding and sizing to obtain a Ti650 high-temperature titanium alloy sheet with a thickness of δ1.2mm.

[0058] Performance test: The plate rolled in Example 1 was verified and analyzed.

[0059] Figure 1~Figure 4This is the high-magnification structure of the head and tail of the δ2.0mm thick Ti650 high-temperature titanium alloy plate prepared in Example 1. It can be seen that the microstructure of the slab is an α+β two-phase region processed structure, all the original β grain boundaries are fully broken, and the microstructure uniformity is good.

[0060] Figures 5 to 8 The high-magnification structure of the head and tail of the δ2.0mm thick Ti650 high-temperature titanium alloy plate prepared in Example 1 after Tβ-(10~40)℃ / 2h, AC+690℃ / 4h, AC heat treatment shows that the slab microstructure is a typical dual-state structure with an equiaxed primary phase content of 10%~15%, ensuring that the alloy has high strength while taking into account good plasticity.

[0061] The mechanical properties of the Ti650 high temperature titanium alloy plate with a thickness of δ2.0 mm prepared in Example 1 were tested, and the results are shown in Table 1.

[0062] Table 1 Finished product properties of Ti650 high temperature titanium alloy plate with a thickness of δ2.0 mm prepared in Example 1

[0063] It can be seen from Table 1 that the difference in transverse and longitudinal properties of δ2.0mmTi650 high-temperature titanium alloy plate is small, and the room temperature tensile elongation is more than 10%, which has excellent plasticity for 600℃~650℃ high-temperature titanium alloy thin plates; 550℃ and 650℃ high-temperature tensile, endurance, creep properties, especially 650℃ high-temperature tensile properties, the comprehensive mechanical properties are at a relatively high level among the existing 600℃~650℃ high-temperature titanium alloy thin plates.

Claims

1. A rolling method for high uniform Ti650 high temperature titanium alloy sheet, characterized in that: The specific steps are as follows: Step 1, subjecting the Ti650 alloy ingot to two-fire blank forging and multi-fire cycle forging to obtain an intermediate forging blank; Step 2, after 100% grinding of the intermediate forging blank, a layer of 1-2 mm pure titanium plate is welded on the upper surface and the lower surface thereof, and the first heating and heat preservation is performed, followed by a first hot rolling to obtain the first semi-finished slab; Step 3, removing the edge defects of the first semi-finished slab, sawing it along its length direction, heating and heat preservation for the second time, and then performing double-heat rolling to obtain a second semi-finished slab; Step 4, the second semi-finished slab is 100% polished, the edge defects are removed, and the slab is sawn and cut into pieces, and then heated and kept warm for the third time, and then three-fire rolling is performed in a continuous tempering manner to obtain a third semi-finished slab; Step 5, after straightening the third semi-finished slab, 100% polishing and removing edge defects are performed, and water jet cutting is used to cut the length and pre-oxidation annealing is performed, and then the annealed multi-layered third semi-finished slab is welded with steel plates and steel bars to form a stacked rolling package; Step 6, heating and heat-insulating the stacked rolling package for the fourth time, and then performing the fourth hot rolling, and then stress relief annealing, stacked rolling package rough sizing, straightening, unpacking, surface sanding and sizing to obtain Ti650 high-temperature titanium alloy plate, wherein the thickness of the Ti650 high-temperature titanium alloy plate is 0.7mm~2.0mm.

2. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 1, characterized in that: In the step 1, the blank forging is carried out at a temperature of 80°C to 150°C above the phase transformation point for a time of 400 to 600 minutes, the final forging temperature is not less than 850°C, and air cooling is performed after breaking.

3. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 2, characterized in that: In the step 1, the Ti650 alloy ingot after 2-time blank forging is 100% polished and then cyclic forging is performed, and the cyclic forging adopts a "low, high" cyclic forging method, wherein the low temperature forging temperature is 30°C to 60°C below the phase transition point temperature, and the high temperature forging temperature is 30°C to 80°C above the phase transition point temperature, and the heating and holding time of each low temperature forging or high temperature forging is a*D min, wherein a is 0.75-0.90, in units of min / mm, and D is the thickness of the forging blank, in units of mm, and 4-6 fires are repeatedly forged, and the final forging temperature is not less than 800°C.

4. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 1, characterized in that: The temperature of the first heating and heat preservation in step 2 is 40°C to 80°C below the phase transition point temperature, the time is 2 to 4 hours, and the final rolling temperature is not less than 800°C; The deformation of the first rolling pass is 5% to 15%, the number of passes is 5 to 10, the rolling rate is 2 m / s to 5 m / s, and the deformation of the first rolling pass is 45% to 65%; the first rolling direction is longitudinal rolling.

5. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 1, characterized in that: The temperature of the second heating and heat preservation in step 3 is 40°C to 80°C below the phase transition point temperature, the time is 1.5 to 3 hours, and the final rolling temperature is not less than 800°C; The deformation of the second-pass rolling is 7% to 20%, the number of passes is 5 to 10, the rolling rate is 2m / s to 5m / s, and the deformation of the second-pass rolling is 45% to 70%; the second-pass rolling direction is along-width rolling.

6. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 1, characterized in that: The temperature of the third heating and heat preservation in step 4 is 40°C to 80°C below the phase transition point temperature, and the time is 1.5 to 2 hours. When the rolling temperature is lower than 800°C, the furnace needs to be returned to the furnace for heating once, and the time of the return to the furnace for heating is 40min to 60min. The final rolling temperature is not lower than 750°C. The deformation of the three-pass rolling is 7% to 20%, the number of passes is 5 to 10, the rolling rate is 2 m / s to 5 m / s, and the deformation of the three-pass rolling is 60% to 90%; The thickness of the third semi-finished slab does not exceed 6 mm.

7. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 1, characterized in that: In step 5, the pre-oxidation annealing temperature is 600° C. to 650° C., and the holding time is 2 hours.

8. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 7, characterized in that: The preparation method of the stacked rolling package in step 5 is: stack 2-4 layers of the third semi-finished slab in sequence, then weld it all around with steel plates and steel bars, and open exhaust holes on the front and rear steel plates, and soft insulation needs to be filled between the steel plates of the stacked rolling package and the stacked slabs.

9. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 1, characterized in that: The temperature of the fourth heating and insulation in step 6 is 40°C to 80°C below the phase transition point temperature, the time is 1 to 2 hours, and the rolling temperature is not less than 800°C; The deformation of the four-fire rolling pass is 7%~20%, the number of passes is 5~10, the rolling rate is 2m / s~5m / s, and the deformation of the fire is 60%~90%.

10. The rolling method of high uniform Ti650 high temperature titanium alloy sheet according to claim 9, characterized in that: In step 6, the stress relief annealing temperature is 600° C. to 650° C. and the temperature is kept for 2 hours.

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