A method for preparing ultra-long high-uniform titanium alloy plates

Abstract

The present invention discloses a method for preparing ultra-long plates of highly uniform titanium alloy, comprising first dividing the large-sized ingots required for preparing the ultra-long plates into four identical unit ingots on average, and reserving a certain processing allowance, and then smelting the unit ingots. After smelting, the unit ingots are mechanically processed. A forging operation is then carried out, and after four identical forging and machining processes, four unit slabs with exactly the same specifications and dimensions are finally obtained. Afterwards, the four identical unit slabs are hot-rolled and then mechanically processed to obtain four unit plates with the same specifications. The four unit plates are vacuum-welded in pairs, and then composite-rolled and mechanically processed to obtain two composite plates. Finally, the two composite plates are vacuum-welded again, heated, and composite-rolled to obtain ultra-long titanium alloy plates. The advantage of the present invention is that it achieves high-uniformity preparation and efficient and stable production of ultra-long titanium alloy plates.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material processing technology, and in particular relates to a method for preparing a highly uniform titanium alloy ultra-long plate. Background Art

[0002] Titanium alloy, as an alloy material with excellent comprehensive properties, boasts lightweight, high strength and toughness, corrosion resistance, and impact resistance. It is currently widely used in a wide range of fields, including aerospace, marine engineering, deep-sea equipment, new energy, and the chemical industry. As these fields continue to expand, the dimensional requirements for titanium alloy materials in equipment are also gradually increasing. For example, the use of ultra-long titanium alloy plates can reduce the number of welds in the production of large equipment, significantly improving the safety and service life of the equipment.

[0003] However, hot working of titanium alloys presents significant processing and deformation challenges due to their low thermal conductivity, high resistance to deformation, and extreme sensitivity to temperature and process parameters. This leads to difficulties in processing and deformation, as well as poor microstructure uniformity. These issues are exacerbated when producing ultra-long titanium alloy plates. On the one hand, overly large ingots can easily lead to metallurgical issues such as compositional inhomogeneity and segregation. On the other hand, forging large ingots not only places extremely high demands on equipment but also makes deformation of the material difficult, making it difficult to fully forge through the core microstructure. Furthermore, the limitations of mill width and opening make it difficult to design the thickness and width of the slab. In addition to these processing difficulties, the production of ultra-long titanium alloy plates also presents a series of challenges, including long processing cycles, large machining allowances, and excessive costs. Directly rolling EB ingots produced in a skull furnace can avoid some of the problems encountered during forging, but it also presents new challenges, such as poor ductility of the EB ingot, a high risk of severe cracking during rolling, and uneven microstructure and coarse grains in the rolled plate. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of existing ultra-long titanium alloy plates, such as high difficulty in processing, long construction period, difficulty in material deformation and poor structural uniformity, and to provide a preparation method for ultra-long titanium alloy plates with high uniformity. The method can effectively avoid the problems of difficult material deformation and difficult forging of core tissue during the preparation of large-size ingots and large-size slabs, improve the interface healing degree of composite plates, enhance the uniformity of material structure after rolling, and realize high-uniformity preparation and efficient and stable production of ultra-long titanium alloy plates.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing ultra-long high-uniform titanium alloy plates adopts a composite rolling process, and the specific steps are as follows:

[0007] S1, Preparation of unit ingots: Calculate the weight of the extra-long plate to obtain the weight of four identical unit plates. Then, calculate the required unit ingot weight based on the unit plate weight and the required processing allowance. The required processing allowance includes the losses incurred during riser removal, surface grinding, forging grinding, slab grinding, plate grinding, head and tail sawing, and other processing. Then, mix the required raw materials and press them into several electrode blocks. After three vacuum consumable arc melting processes, the titanium alloy unit ingots are prepared.

[0008] S2, preparation of unit slabs: four identical titanium alloy unit ingots are subjected to multi-fire forging and surface treatment, including high-temperature ingot forging, phase transformation point forging, two-phase zone forging, slab forming forging, and slab surface treatment, to prepare the required four titanium alloy unit slabs;

[0009] S3, rolling of unit plates: heating four identical titanium alloy unit plates and performing one-fire reversing rolling to prepare the required four titanium alloy unit plates;

[0010] S4, preparation of composite slab A: milling, grinding, and polishing the first and second unit plates obtained in step S3, then shot blasting and pickling the surfaces, cleaning the contact surfaces of the two plates with alcohol or acetone, and then drying them, then processing grooves on the edges of the first and second unit plates, lightly grinding the processed grooves to remove burrs, wiping them clean with alcohol or acetone, and then air-drying them, then overlapping and aligning the first and second unit plates, and fixing them with spot welding rods around them. After fixing, they are sealed by vacuum electron beam welding to obtain composite slab A;

[0011] S5, preparation of composite plate A: heating the sealed and welded composite plate blank A and performing a hot rolling process to obtain composite plate A;

[0012] S6, preparation of composite plate B: repeating the process of steps S4 and S5 to prepare composite plate B identical to composite plate A from the third and fourth unit plates;

[0013] S7, welding of composite slabs: milling, grinding, and polishing composite sheets A and B, then processing the surfaces by shot blasting and pickling, cleaning the contact surfaces with alcohol or acetone, and then drying. Then, grooves are processed on the edges of composite sheets A and B respectively, and the processed grooves are lightly polished to remove burrs, then wiped clean with alcohol or acetone, and blown dry. Then, composite sheets A and B are overlapped and aligned, and fixed by spot welding around them with welding rods. After fixing, vacuum electron beam welding is used for sealing to obtain edge-sealed laminated slabs;

[0014] S8, preparation of super-long plates: heating the edge-sealed laminated slab and performing single-fire rolling to obtain the final super-long plates;

[0015] S9, preparation of finished plate: annealing, cutting and surface treatment are performed on the extra-long plate in sequence to obtain the finished plate.

[0016] Furthermore, in step S2, the ingot detection phase transition point is T β The high temperature forging of the ingot is to place the ingot in a resistance furnace and heat it to 750℃~900℃, and keep it at this temperature for 4~12h, and then heat it to T β +100℃~T β +200℃ and keep warm with a thermal insulation coefficient of 0.7-0.8. Forge after taking out of the furnace and control the upsetting deformation of forging to 30%-45%. Air cool after forging.

[0017] Furthermore, in step S2, the ingot detection phase transition point is T β The phase transformation point forging includes placing the alloy billet after high temperature forging in a resistance furnace and heating it to 750℃~900℃, keeping it at this temperature for 4~12h, and then heating it to T β +50℃~T β +100℃, thermal insulation coefficient is 0.7~0.8, forging is carried out after taking out of the furnace, and the upsetting deformation is controlled at 40%~50%, and air cooling is completed after forging.

[0018] Furthermore, in step S2, the ingot detection phase transition point is T β The two-phase forging process involves heating the forged blank above the phase transition point for 2 to 5 times below the phase transition point. The heating temperature is T β -50℃~T β -30℃, insulation coefficient is 0.6~0.8. Forging is carried out after the furnace is taken out, and the upsetting deformation is controlled at 35%~45%. The surface temperature of the alloy forging billet is lower than T β At -150℃, heat and keep warm in the hot furnace, control the insulation coefficient to 0.2~0.3, and air cool after forging.

[0019] Furthermore, in step S2, the ingot detection phase transition point is T β , in which the slab forming forging will forge the billet in the two-phase zone at T β -60℃~T β Heating at -30℃, the insulation coefficient is 0.7~0.8, and the surface temperature of the alloy forging billet is lower than T β At -150℃, the hot state is returned to the furnace for heating and insulation, and the insulation coefficient is controlled to be 0.2-0.3. After forging, it is air-cooled and the surface oxide scale is removed by milling to obtain the designed formed slab.

[0020] Furthermore, in step S3, the first hot rolling of the unit slab is to heat the slab to T β -40℃~T β -20℃, holding time is 1.4~1.6min / mm, total deformation per pass is 60~80%, deformation per pass can be controlled at 6%~18%, and rolling speed is controlled at 1m / s~1.5m / s.

[0021] Furthermore, in step S4, the first and second unit plates are milled, ground and polished, requiring the roughness Ra≤8.0μm, the plate unevenness less than 8mm / m, the edge groove angle of 8°~15°, and the weld depth of vacuum electron beam sealing of 25~40mm.

[0022] Furthermore, in step S5, the first hot rolling of the combined slab A is to heat the slab to T β -30℃~T β -20℃, holding time is 1.8~2.0min / mm, total deformation of each pass is 30~50%, deformation of each pass can be controlled at 3%~6%, rolling speed is controlled at 0.5m / s~1m / s, if the surface temperature of the plate is lower than T β At -150℃, the steel can be returned to the furnace and then rolled again.

[0023] Furthermore, in step S7, composite plate A and composite plate B are milled, ground and polished, requiring the roughness to be Ra≤8.0μm, the plate unevenness to be less than 10mm / m, the edge groove angle to be 10°~18°, and the weld depth of vacuum electron beam sealing to be 30~45mm.

[0024] Furthermore, in step S8, the first hot rolling of the edge-sealed laminated slab is to heat the slab to T β -30℃~T β -20℃, holding time is 1.8~2.0min / mm, total deformation of each pass is 30~50%, deformation of each pass can be controlled at 2%~4%, rolling speed is controlled at 0.5m / s~0.8m / s, if the surface temperature of the plate is lower than T β At -150℃, the steel can be returned to the furnace and then rolled again.

[0025] Compared with the prior art, the advantages of the technical solution of the present invention are:

[0026] (1) The present invention innovatively proposes a process route of "unit melting-multiple-fire forging-composite rolling". By dividing the large-sized ingot of the target ultra-long plate into four small unit ingots, the risk of composition segregation during the melting process is significantly reduced. At the same time, after three VAR vacuum consumable arc melting of the small-sized ingot, the composition uniformity is improved. Combined with the refinement effect of multi-fire forging, the uniformity of the unit slab structure is significantly better than that of the large-sized slab.

[0027] (2) Since the slab size of the ultra-long plate far exceeds the rolling force and opening of the conventional rolling mill, direct rolling is difficult to implement. Therefore, the present invention adopts a step-by-step composite rolling strategy of "unit plate → two-by-two composite → secondary composite": first, four small unit plates are vacuum welded in pairs to form composite plates A / B, and then A / B are composited into the final ultra-long plate. By composited in stages, the limitation of the rolling mill equipment capacity is effectively circumvented; at the same time, the unit plate has completed the reversing rolling and microstructure refinement, and only a small deformation amount is required to achieve interface healing during composite rolling, breaking through the deformation difficulty problem of direct rolling of large slabs;

[0028] (3) The present invention is designed to melt, forge, and roll small-sized unit ingots / slabs, and its parameters are easier to control, significantly reducing quality problems caused by equipment fluctuations. Compared with the traditional one-time processing of large-sized slabs, the present invention greatly shortens the processing cycle through the parallel production of four units;

[0029] (4) The present invention adopts standardized preparation of unit plates, which greatly improves the performance consistency of ultra-long plates after composite rolling, and the batch stability is significantly better than the traditional process. While avoiding the metallurgical risks of large-scale ingots and breaking through equipment limitations, it achieves highly uniform preparation and efficient and stable production of ultra-long titanium alloy plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a metallographic structure diagram of the titanium alloy plate after hot rolling in Example 1 of the present invention;

[0031] Figure 2 The table shows the mechanical properties and CV values ​​at various positions of the titanium alloy plates after rolling and annealing in Examples 1 to 3 of the present invention. DETAILED DESCRIPTION Example 1

[0032] To make the present invention more clear, the preparation method of a high-uniform titanium alloy ultra-long plate of the present invention is further described below in conjunction with the accompanying drawings. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0033] The present invention adopts a composite rolling method, firstly, the large-size ingot required for preparing the ultra-long plate is evenly divided into four identical unit ingots, and a certain processing allowance is reserved, and then the unit ingots are smelted. After the smelting is completed, the unit ingots are mechanically processed; then a forging operation is carried out, and after four identical forging and mechanical processing steps, four unit slabs with exactly the same specifications and dimensions are finally obtained; then these four identical unit slabs are hot-rolled and then mechanically processed to obtain four unit plates with the same specifications; then these four unit plates are vacuum-welded in pairs, and then composite-rolled and mechanically processed to obtain two composite plates; finally, the two composite plates are vacuum-welded again, heated, and composite-rolled to obtain the titanium alloy ultra-long plate.

[0034] In this embodiment, taking Ti80 titanium alloy ultra-long plate as an example, a method for preparing ultra-long high-uniform titanium alloy plate is provided, comprising the following steps, characterized in that:

[0035] (1) The required specifications for an ultra-long Ti80 titanium alloy plate are 80 mm thick, 2000 mm wide, and 8000 mm long. The plate weighs approximately 6 t, so the unit plate weighs approximately 1.5 t. Based on the unit plate weight and the required machining allowance, the unit ingot weight is calculated to be 2.2 t. After calculating the machining allowance for each unit ingot, the required raw materials are mixed and pressed into several electrode blocks. After three VAR vacuum consumable arc melting processes, the titanium alloy unit ingot is produced.

[0036] (2) Four identical titanium alloy unit ingots were subjected to multi-fire forging and surface treatment. The unit slab design specifications were: 240 mm thick, 1200 mm wide, and 1500 mm long. The ingot was tested for phase transition point at 995°C. The ingot was forged at high temperature by placing it in a resistance furnace and heating it to 850°C and holding it for 6 hours. The ingot was then heated to 1150°C and held at that temperature with a holding coefficient of 0.7. After being taken out of the furnace, it was forged, with the upsetting deformation of the forging controlled at 40%. After forging, it was air-cooled.

[0037] Phase transformation point forging involves heating the alloy billet after high-temperature forging in a resistance furnace to 850°C and holding it for 6 hours. The billet is then heated to 1080°C with a holding coefficient of 0.8. After exiting the furnace, forging is performed with a holding coefficient of 0.3 and an upset deformation of 45%. The billet is then air-cooled after forging.

[0038] Two-phase forging involves heating the billet above the phase transition point three times below the phase transition point at a heating temperature of 960°C and a holding coefficient of 0.7. After forging, the billet is forged with an upset deformation of 40%. During each forging process, when the surface temperature of the alloy billet falls below 845°C, it is returned to the hot furnace for heating and holding, with a holding coefficient of 0.3. After forging, it is air-cooled.

[0039] In the slab forming forging, the two-phase zone forged billet is heated at 960°C with a thermal insulation coefficient of 0.7. When the surface temperature of the alloy forging billet is lower than 845°C during the forging process, it is returned to the hot furnace for heating and insulation, and the thermal insulation coefficient is controlled to be 0.2. After forging, it is air-cooled and the surface oxide scale is removed by milling to obtain the designed formed slab.

[0040] (3) Four identical titanium alloy unit slabs were heated and rolled in one pass. The slabs were heated to 970°C and held at this temperature for 360 minutes. The total deformation of each pass was 75%, and the deformation of each pass was controlled at 8% to 10%. When rolling began, the long side of the slab was 1500 mm wide. When the thickness reached 135 mm, the width had been reduced from 1200 mm to 2133 mm. The slabs were then reversed and rolled to a thickness of 61 mm before stopping. The rolling speed was controlled at 1.2 m / s. The four required titanium alloy unit slabs were prepared. The dimensions of the slabs after cutting were: 61 mm thick, 2100 mm wide, and 3200 mm long.

[0041] (4) The first and second unit plates obtained in the above steps are milled, ground and polished to a thickness of 60 mm, a roughness of Ra ≤ 8.0 μm, and a plate unevenness of less than 8 mm / m. The surfaces are processed by shot blasting and pickling, and the contact surfaces are cleaned with alcohol or acetone and then dried. Then, the edges of the first and second unit plates are respectively processed with grooves, with an edge groove angle of 8°. The processed grooves are lightly polished to remove burrs, wiped clean with alcohol or acetone, and blown dry. Then, the first and second unit plates are overlapped and aligned, and fixed with welding rods around them. After fixing, they are sealed with vacuum electron beam welding, and the weld depth is 30 mm to obtain a composite plate A. The dimensions of the composite plate are: thickness 120 mm, width 2100 mm, and length 3200 mm.

[0042] (5) The sealed composite slab A was heated and rolled in one pass. The slab was heated to 970°C and held at this temperature for 220 min. The total deformation per pass was 41%, and the deformation per pass was controlled at 4%. If the surface temperature of the slab fell below 845°C during rolling, it was returned to the furnace and rolled again. Rolling was stopped after the thickness reached 71 mm. The rolling speed was controlled at 0.8 m / s. Composite slab A was produced. The dimensions of the slab after cutting were: 71 mm thick, 2100 mm wide, and 5200 mm long.

[0043] (6) Repeat steps (4) and (5) to prepare a composite plate B identical to composite plate A using the third and fourth unit plates.

[0044] (7) The composite plates A and B are milled, ground and polished to a thickness of 70 mm, a roughness of Ra ≤ 8.0 μm, and a plate unevenness of less than 8 mm / m. The surfaces are processed by shot blasting and pickling, and the contact surfaces are cleaned with alcohol or acetone and then dried. Then, the edges of the composite plates A and B are respectively processed with grooves, and the edge groove angle is 8°. The processed grooves are lightly polished to remove burrs, wiped clean with alcohol or acetone, and blown dry. Then, the composite plates A and B are overlapped and aligned, and fixed with welding rods around them. After fixing, vacuum electron beam welding is used for sealing. The weld depth is 35 mm, and the edge-sealed laminated plate blank is obtained with the dimensions of: 140 mm thick, 2100 mm wide, and 5200 mm long.

[0045] (8) The final edge-sealed laminated slab is subjected to a single-pass rolling process. The slab is heated to 970°C and held at this temperature for 260 minutes. The total deformation per pass is 42%, and the deformation per pass can be controlled at 3%. If the surface temperature of the slab is lower than 845°C during rolling, it can be returned to the furnace and then rolled again. Rolling is stopped after the thickness reaches 82 mm. The rolling speed is controlled at 0.8 m / s to obtain the final super-long slab. The dimensions of the slab after rolling are: 82 mm thick, 2100 mm wide, and 8800 mm long.

[0046] (9) The extra-long sheet obtained in step S8 is annealed at 970°C for 3 h and then air-cooled. After annealing, the sheet is cut and surface treated to obtain a finished sheet with dimensions of 80 mm thick, 2000 mm wide, and 8000 mm long.

[0047] The structure of the plate after hot rolling is shown in Figure 1 , the performance of the plate after annealing is shown in Figure 2 The table shown. Example 2

[0048] In this embodiment, taking TC4 titanium alloy ultra-long plate as an example, a method for preparing ultra-long high-uniform titanium alloy plate is provided, comprising the following steps, characterized in that:

[0049] (1) The required specifications for an ultra-long TC4 titanium alloy plate are 100 mm thick, 2000 mm wide, and 9000 mm long. The plate weighs approximately 8.1 t, so the unit plate weighs approximately 2.1 t. Based on the unit plate weight and the required machining allowance, the unit ingot weight is calculated to be 2.8 t. After calculating the machining allowance for each unit ingot, the required raw materials are mixed and pressed into several electrode blocks. After three VAR vacuum consumable arc melting processes, the unit titanium alloy ingot is produced.

[0050] (2) Four identical titanium alloy unit ingots were subjected to multi-fire forging. The unit slab design specifications were: 320 mm thick, 1300 mm wide, and 1400 mm long. The ingot was tested for phase transition point at 990°C. The ingot was placed in a resistance furnace and heated to 850°C for 8 hours. The temperature was then raised to 1120°C and held at that temperature with a holding coefficient of 0.7. After being taken out of the furnace, the ingot was forged. The upsetting deformation during forging was controlled at 40%. After forging, the ingot was air-cooled.

[0051] Phase transformation point forging includes placing the alloy billet after high-temperature forging in a resistance furnace, heating it to 850°C, and keeping it warm for 8 hours, then heating it to 1050°C with a holding coefficient of 0.8, forging it after it is taken out of the furnace, controlling the holding coefficient to 0.3, controlling the upsetting deformation to 45%, and air cooling after forging.

[0052] Two-phase zone forging includes heating the billet forged above the phase transformation point for three times below the phase transformation point, with a heating temperature of 950°C and a thermal insulation coefficient of 0.7. The billet is then forged after being taken out of the furnace, and the upsetting deformation is controlled at 40%. When the surface temperature of the alloy billet is lower than 840°C during each forging process, the billet is returned to the furnace for heating and insulation, with a thermal insulation coefficient of 0.3. After forging, the billet is air-cooled.

[0053] In the slab forming forging, the two-phase zone forged billet is heated at 950°C with a thermal insulation coefficient of 0.7. When the surface temperature of the alloy forging billet is lower than 840°C during the forging process, it is returned to the furnace for heating and insulation, and the thermal insulation coefficient is controlled to be 0.2. After forging, it is air-cooled and the surface oxide scale is removed by milling to obtain the designed formed slab.

[0054] (3) Four identical titanium alloy unit slabs were heated and rolled in one pass. The slabs were heated to 970°C and held at this temperature for 450 minutes. The total deformation of each pass was 71.3%, and the deformation of each pass was controlled between 6% and 10%. The slabs were rolled with a long side of 1400 mm as the width. When the thickness reached 195 mm, the width had been reduced from 1300 mm to 2133 mm. The slabs were then reversed and rolled to a thickness of 92 mm before stopping. The rolling speed was controlled at 1.2 m / s. The four titanium alloy unit slabs required were prepared. The dimensions of the slabs after cutting were: 92 mm thick, 2100 mm wide, and 2800 mm long.

[0055] (4) The first and second unit plates obtained in the above steps are milled, ground and polished to a thickness of 90 mm, a roughness of Ra ≤ 8.0 μm, and a plate unevenness of less than 8 mm / m. The surfaces are processed by shot blasting and pickling, and the contact surfaces are cleaned with alcohol or acetone and then dried. Then, the edges of the first and second unit plates are respectively processed with grooves, with an edge groove angle of 10°. The processed grooves are lightly polished to remove burrs, wiped clean with alcohol or acetone, and blown dry. Then, the first and second unit plates are overlapped and aligned, and fixed with spot welding around them with welding rods. After fixing, vacuum electron beam welding is used for sealing. The weld depth is 35 mm to obtain a composite plate A. The dimensions of the composite plate are: 180 mm thick, 2100 mm wide, and 2800 mm long.

[0056] (5) The sealed composite slab A was heated and rolled in one pass. The slab was heated to 970°C and held at this temperature for 360 min. The total deformation per pass was 45.5%, and the deformation per pass was controlled to 4%. If the surface temperature of the slab fell below 840°C during rolling, it was returned to the furnace and rolled again. Rolling was stopped after the thickness reached 98 mm. The rolling speed was controlled at 0.8 m / s. Composite slab A was produced. The dimensions of the slab after cutting were: 98 mm thick, 2100 mm wide, and 5000 mm long.

[0057] (6) Repeat steps (4) and (5) to prepare a composite plate B identical to composite plate A using the third and fourth unit plates.

[0058] (7) The composite sheets A and B are milled, ground and polished to a thickness of 96 mm, a roughness of Ra ≤ 8.0 μm, and a sheet unevenness of less than 8 mm / m. The surfaces are processed by shot blasting and pickling, and the contact surfaces are cleaned with alcohol or acetone and then dried. Then, the edges of the composite sheets A and B are respectively processed with grooves, with an edge groove angle of 10°. The processed grooves are lightly polished to remove burrs, wiped clean with alcohol or acetone, and blown dry. Then, the composite sheets A and B are overlapped and aligned, and fixed with spot welding around them with welding rods. After fixing, vacuum electron beam welding is used for sealing. The weld depth is 40 mm, and the edge-sealed laminated sheet blank is obtained with the dimensions of: 192 mm thick, 2100 mm wide, and 5000 mm long.

[0059] (8) The final edge-sealed laminated slab was subjected to a single-pass rolling process. The slab was heated to 970°C and held at this temperature for 360 minutes. The total deformation of each pass was 47%, and the deformation of each pass was controlled at 3%. If the surface temperature of the slab was lower than 840°C during the rolling process, it was returned to the furnace and then continued rolling. The rolling process was stopped after the thickness reached 102 mm. The rolling speed was controlled at 0.6 m / s to obtain the final super-long slab. The dimensions of the slab after rolling were: 102 mm thick, 2100 mm wide, and 9400 mm long.

[0060] (9) The final super-long plate is annealed at 850℃, kept at this temperature for 4 hours, and then air-cooled. After annealing, the plate is cut and surface treated to obtain the finished plate with the following dimensions: thickness 100mm, width 2000mm, length 9000mm. The performance of the plate after annealing is shown in Figure 2 The table shown. Example 3

[0061] In this embodiment, taking TC4 titanium alloy ultra-long plate as an example, a method for preparing ultra-long high-uniform titanium alloy plate is provided, comprising the following steps, characterized in that:

[0062] (1) The required specifications for a TC4 titanium alloy ultra-long plate are 120 mm thick, 2500 mm wide, and 9000 mm long. The plate weighs approximately 12.2 t, so the unit plate weighs approximately 3.1 t. Based on the unit plate weight and the required machining allowance, the unit ingot weight is calculated to be 4.1 t. After calculating the machining allowance for each unit ingot, the required raw materials are mixed and pressed into several electrode blocks. After three VAR vacuum consumable arc melting processes, the unit titanium alloy ingot is produced.

[0063] (2) Four identical titanium alloy unit ingots were subjected to multi-fire forging. The unit slab design specifications were: 360 mm thick, 1600 mm wide, and 1500 mm long. The ingot was tested for phase transition point at 1000°C. The ingot was placed in a resistance furnace and heated to 850°C for 9 hours. The ingot was then heated to 1130°C and held at that temperature with a holding coefficient of 0.7. After being taken out of the furnace, the ingot was forged. The upsetting deformation during forging was controlled at 40%. After forging, the ingot was air-cooled.

[0064] Phase transformation point forging includes placing the alloy billet after high-temperature forging in a resistance furnace, heating it to 850°C, and keeping it warm for 9 hours, then heating it to 1060°C with a holding coefficient of 0.8, forging it after it is taken out of the furnace, controlling the holding coefficient to 0.3, controlling the upsetting deformation to 45%, and air cooling after forging.

[0065] Two-phase zone forging includes heating the billet above the phase transformation point for 4 rounds at a heating temperature of 950°C and a holding coefficient of 0.7. The billet is then forged after being taken out of the furnace, and the upsetting deformation is controlled at 40%. When the surface temperature of the alloy billet is lower than 850°C during each forging process, the billet is returned to the furnace for heating and holding, and the holding coefficient is controlled at 0.3. After forging, the billet is air-cooled.

[0066] In the slab forming forging, the two-phase zone forged billet is heated at 950°C with a thermal insulation coefficient of 0.7. When the surface temperature of the alloy forging billet is lower than 850°C during the forging process, it is returned to the furnace for heating and insulation, and the thermal insulation coefficient is controlled to be 0.3. After forging, it is air-cooled and the surface oxide scale is removed by milling to obtain the designed formed slab.

[0067] (3) Four identical titanium alloy unit slabs were heated and rolled in one pass. The slabs were heated to 975°C and held at this temperature for 540 minutes. The total deformation of each pass was 71.7%, and the deformation of each pass was controlled between 6% and 10%. The slabs were rolled with a long side of 1500 mm as the width. When the thickness reached 215 mm, the width had been reduced from 1600 mm to 2679 mm. The slabs were then reversed and rolled to a thickness of 102 mm before stopping. The rolling speed was controlled at 1.2 m / s. The four titanium alloy unit slabs required were prepared. The dimensions of the slabs after cutting were: 102 mm thick, 2600 mm wide, and 3000 mm long.

[0068] (4) The first and second unit plates obtained in the above steps are milled, ground and polished to a thickness of 100 mm, a roughness of Ra ≤ 8.0 μm, and a plate unevenness of less than 8 mm / m. The surfaces are processed by shot blasting and pickling, and the contact surfaces are cleaned with alcohol or acetone and then dried. Then, the edges of the first and second unit plates are respectively beveled, with an edge bevel angle of 12°. The processed bevels are lightly polished to remove burrs, wiped clean with alcohol or acetone, and blown dry. Then, the first and second unit plates are overlapped and aligned, and fixed by spot welding around them with welding rods. After fixing, vacuum electron beam welding is used for sealing, and the weld depth is 40 mm to obtain a composite plate A. The dimensions of the composite plate are: 200 mm thick, 2600 mm wide, and 3000 mm long.

[0069] (5) The sealed composite slab A was heated and rolled in one pass. The slab was heated to 970°C and held at this temperature for 380 min. The total deformation per pass was 44%, and the deformation per pass was controlled to 3%. If the surface temperature of the slab dropped below 850°C during rolling, it was returned to the furnace and rolled again. Rolling was stopped after the thickness reached 112 mm. The rolling speed was controlled at 0.8 m / s. Composite slab A was produced. The dimensions of the slab after cutting were: 110 mm thick, 2600 mm wide, and 5200 mm long.

[0070] (6) Repeat steps (4) and (5) to prepare a composite plate B identical to composite plate A using the third and fourth unit plates.

[0071] (7) The composite plates A and B are milled, ground and polished to a roughness of Ra ≤ 8.0 μm and a plate unevenness of less than 8 mm / m. The surfaces are processed by shot blasting and pickling, and the contact surfaces are cleaned with alcohol or acetone and then dried. Then, the edges of the composite plates A and B are respectively processed with grooves, with an edge groove angle of 12°. The processed grooves are lightly polished to remove burrs, wiped clean with alcohol or acetone, and blown dry. Then, the composite plates A and B are overlapped and aligned, and fixed with spot welding around them with welding rods. After fixing, vacuum electron beam welding is used for sealing. The weld depth is 40 mm, and the edge-sealed laminated plate blank is obtained with dimensions of: 220 mm thick, 2600 mm wide, and 5200 mm long.

[0072] (8) The final edge-sealed laminated slab is subjected to a single-pass rolling process. The slab is heated to 970°C and held at this temperature for 430 minutes. The total deformation per pass is 45%, and the deformation per pass can be controlled at 3%. If the surface temperature of the slab is lower than 850°C during rolling, it can be returned to the furnace and then rolled again. Rolling is stopped after the thickness reaches 122 mm. The rolling speed is controlled at 0.6 m / s to obtain the final super-long slab. The dimensions of the slab after rolling are: 122 mm thick, 2600 mm wide, and 9370 mm long.

[0073] (9) The final super-long plate is annealed at 850℃, kept at this temperature for 6 hours, and then air-cooled. After annealing, the plate is cut and surface treated to obtain the finished plate with the following dimensions: thickness 120mm, width 2500mm, length 9000mm. The performance of the plate after annealing is shown in Figure 2 The table shown.

[0074] In summary, Figure 1 The microstructure of the titanium alloy plate after hot rolling in Example 1 shows a primary α-phase content of approximately 70%. The average grain size is 29 μm. The ultra-long Ti80 alloy plate rolled using this method exhibits a relatively uniform microstructure and meets all standard performance requirements. A CV value of less than 15% indicates relatively stable values, i.e., minimal dimensional variation in the plate. The same conclusion can be drawn based on the performance of Examples 2 and 3. In summary, this process can meet the standard microstructure and performance requirements for this alloy grade, while also ensuring product performance and microstructure stability.

[0075] The process of the present invention, based on composite rolling, effectively avoids the difficulties encountered in the preparation of large-scale ingots and slabs. Furthermore, the preparation of unit plates and the multiple composite rolling processes ensure high uniformity in ultra-long titanium alloy plates. Furthermore, since the unit plates have already undergone microstructure refinement, the deformation and rolling speed can be appropriately reduced during composite rolling, thereby improving the degree of interface healing in the composite plate and ensuring that the rolled composite plate meets performance requirements.

[0076] In addition to the above embodiments, the present invention may also have other implementations. Any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection required by the present invention.

Claims

1. A method for preparing a high-uniform titanium alloy ultra-long plate, characterized by: S1, Preparation of unit ingots: Calculate the weight of the extra-long plate to obtain the weight of four identical unit plates. Then, calculate the required unit ingot weight based on the unit plate weight and the required processing allowance. The required processing allowance includes the losses incurred during riser removal, surface grinding, forging grinding, slab grinding, plate grinding, and head and tail sawing. Then, the required raw materials are mixed and pressed into several electrode blocks. After three vacuum consumable arc melting processes, the titanium alloy unit ingots are prepared. S2, preparation of unit slabs: four identical titanium alloy unit ingots are subjected to multi-fire forging and surface treatment, including high-temperature ingot forging, phase transformation point forging, two-phase zone forging, slab forming forging, and slab surface treatment, to prepare the required four titanium alloy unit slabs; S3, rolling of unit plates: heating four identical titanium alloy unit plates and performing one-fire reversing rolling to prepare the required four titanium alloy unit plates; S4, preparation of composite slab A: milling, grinding, and polishing the first and second unit plates obtained in step S3, then shot blasting and pickling the surfaces, cleaning the contact surfaces of the two plates with alcohol or acetone, and then drying them, then processing grooves on the edges of the first and second unit plates, lightly grinding the processed grooves to remove burrs, wiping them clean with alcohol or acetone, and then air-drying them, then overlapping and aligning the first and second unit plates, and fixing them with spot welding rods around them. After fixing, they are sealed by vacuum electron beam welding to obtain composite slab A; S5, preparation of composite plate A: heating the sealed and welded composite plate blank A and performing a hot rolling process to obtain composite plate A; S6, preparation of composite plate B: repeating the process of steps S4 and S5 to prepare composite plate B identical to composite plate A using the third and fourth unit plates; S7, welding of composite slabs: milling, grinding, and polishing composite sheets A and B, then processing the surfaces by shot blasting and pickling, cleaning the contact surfaces with alcohol or acetone, and then drying. Then, grooves are processed on the edges of composite sheets A and B respectively, and the processed grooves are lightly polished to remove burrs, then wiped clean with alcohol or acetone, and blown dry. Then, composite sheets A and B are overlapped and aligned, and fixed by spot welding around them with welding rods. After fixing, vacuum electron beam welding is used for sealing to obtain edge-sealed laminated slabs; S8, preparation of super-long plates: heating the edge-sealed laminated slab and performing single-fire rolling to obtain the final super-long plates; S9, preparation of finished plate: annealing, cutting and surface treatment are performed on the extra-long plate in sequence to obtain the finished plate.

2. The method for preparing a high-uniform titanium alloy ultra-long plate according to claim 1, characterized in that: In step S2, the ingot detection phase transition point is T β The high temperature forging of the ingot is to place the ingot in a resistance furnace and heat it to 750℃~900℃, and keep it at this temperature for 4~12h, and then heat it to T β +100℃~T β +200℃ and keep warm with a thermal insulation coefficient of 0.7-0.

8. Forge after taking out of the furnace and control the upsetting deformation of forging to 30%-45%. Air cool after forging.

3. The method for preparing a high-uniform titanium alloy ultra-long plate according to claim 1, characterized in that: In step S2, the ingot detection phase transition point is T β The phase transformation point forging includes placing the alloy billet after high temperature forging in a resistance furnace and heating it to 750℃~900℃, keeping it at this temperature for 4~12h, and then heating it to T β +50℃~T β +100℃, thermal insulation coefficient is 0.7~0.8, forging is carried out after taking out of the furnace, and the upsetting deformation is controlled at 40%~50%, and air cooling is completed after forging.

4. The method for preparing a high-uniform titanium alloy ultra-long plate according to claim 1, characterized in that: In step S2, the ingot detection phase transition point is T β The two-phase forging process involves heating the forged blank above the phase transition point for 2 to 5 times below the phase transition point. The heating temperature is T β -50℃~T β -30℃, insulation coefficient is 0.6~0.8, forging is carried out after the furnace is taken out, and the upsetting deformation is controlled at 35%~45%. During each forging process, the surface temperature of the alloy forging billet is lower than T β At -150℃, heat and keep warm in the hot furnace, control the insulation coefficient to 0.2~0.3, and air cool after forging.

5. The method for preparing a high-uniform titanium alloy ultra-long plate according to claim 1, characterized in that: In step S2, the ingot detection phase transition point is T β , in which the slab forming forging will forge the billet in the two-phase zone at T β -60℃~T β Heating at -30℃, the insulation coefficient is 0.7~0.8, and the surface temperature of the alloy forging billet is lower than T β At -150℃, the hot state is returned to the furnace for heating and insulation, and the insulation coefficient is controlled to be 0.2-0.

3. After forging, it is air-cooled and the surface oxide scale is removed by milling to obtain the designed formed slab.

6. The method for preparing a high-uniform titanium alloy ultra-long plate according to any one of claims 2 to 5, characterized in that: In step S3, the first hot rolling of the unit slab is to heat the slab to T β -40℃~T β -20℃, holding time is 1.4~1.6min / mm, total deformation per pass is 60~80%, deformation per pass can be controlled at 6%~18%, and rolling speed is controlled at 1m / s~1.5m / s.

7. The method for preparing a high-uniform titanium alloy ultra-long plate according to any one of claims 1 to 5, characterized in that: In step S4, the first and second unit plates are milled, ground and polished, requiring a roughness Ra ≤ 8.0 μm, plate unevenness less than 8 mm / m, an edge groove angle of 8° to 15°, and a weld depth of 25 to 40 mm for vacuum electron beam sealing.

8. The method for preparing a high-uniform titanium alloy ultra-long plate according to any one of claims 2 to 5, characterized in that: In step S5, the first hot rolling of the composite slab A is to heat the slab to T β -30℃~T β -20℃, holding time is 1.8~2.0min / mm, total deformation of each pass is 30~50%, deformation of each pass can be controlled at 3%~6%, rolling speed is controlled at 0.5m / s~1m / s, if the surface temperature of the plate is lower than T β At -150℃, the steel can be returned to the furnace and then rolled again.

9. The method for preparing a high-uniform titanium alloy ultra-long plate according to any one of claims 1 to 5, characterized in that: In step S7, composite plate A and composite plate B are milled, ground and polished, with the roughness requirement of Ra≤8.0μm, plate unevenness less than 10mm / m, edge groove angle of 10°~18°, and vacuum electron beam sealing weld depth of 30~45mm.

10. The method for preparing a high-uniform titanium alloy ultra-long plate according to any one of claims 2 to 5, characterized in that: In step S8, the first hot rolling of the edge-sealed laminated slab is to heat the slab to T β -30℃~T β -20℃, holding time is 1.8~2.0min / mm, total deformation of each pass is 30~50%, deformation of each pass can be controlled at 2%~4%, rolling speed is controlled at 0.5m / s~0.8m / s, if the surface temperature of the plate is lower than T β At -150℃, the steel can be returned to the furnace and then rolled again.

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