High-yield titanium alloy thick plate and preparation method thereof
By optimizing the slab size and rolling process, and adopting reversing rolling and vertical roll rolling, the problems of cracking and low yield of titanium alloy thick plates during hot rolling were solved, achieving high yield and short cycle production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU XIANGYUN TITANIUM ALLOY NEW MATERIALS CO LTD
- Filing Date
- 2026-02-28
- Publication Date
- 2026-04-17
AI Technical Summary
During the hot rolling process of titanium alloy thick plates, high-strength, low-plasticity materials such as TA15, TC4, and TC11 are prone to defects such as cracking, delamination, and tongue-like defects, resulting in low yield and long production cycle.
By coordinating the design of slab size, shape and rolling process parameters, adopting reversing rolling and vertical roll rolling, the slab shape is optimized, cracks are reduced, the head and tail trimming process after the first rolling is eliminated, and the yield is improved.
It significantly improves the yield of titanium alloy thick plates to over 85%, shortens the processing cycle by 1 to 2 days, and meets the needs of efficient and low-cost manufacturing.
Smart Images
Figure CN121869860A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of non-ferrous metal material processing technology, and in particular to a high yield titanium alloy thick plate and its preparation method. Background Technology
[0002] Titanium alloy thick plates, with their excellent properties such as lightweight, high strength, corrosion resistance, and high temperature resistance, have become the preferred material for key structural components in aerospace, marine engineering, and other fields. In the rolling process of titanium alloy thick plates, to fully break down the grain structure, improve the uniformity of the microstructure, and enhance the overall mechanical properties, a two-stage hot rolling process (single-stage hot rolling + slitting and blanking + second-stage hot rolling) is often used.
[0003] However, for some high-strength, low-ductility titanium alloy materials, such as TA15, TC4, and TC11, defects such as cracking, delamination, and tongue-like defects often appear on the plates after hot rolling. These defects not only seriously affect the final quality of the product but also significantly reduce the rolling yield, hindering the improvement of the product qualification rate. The traditional solution is to cut off the defective head and tail areas after each hot rolling cycle. While this method can ensure the quality of the product to a certain extent, it also leads to problems such as extended processing cycles and low material utilization, making it difficult to meet the current development requirements of efficient and low-cost manufacturing of thick titanium alloy plates. Summary of the Invention
[0004] To address the aforementioned shortcomings in existing technologies, this invention innovatively proposes a method for preparing high-yield titanium alloy thick plates. The core of this method lies in the coordinated design of slab dimensions, slab shape, and rolling process parameters, fully leveraging the advantages of reversing rolling and vertical roll rolling in improving plate shape uniformity and suppressing localized stress concentration, thereby optimizing plate shape and reducing cracks.
[0005] Based on this preparation method, the end-and-end trimming process after the first rolling can be eliminated while ensuring product quality, and the material loss after the second rolling can be significantly reduced. Practical applications show that this invention can increase the rolling yield of titanium alloy thick plates to over 85% and shorten the processing cycle by 1 to 2 days, which can better meet the current industry's development needs for efficient and low-cost manufacturing of titanium alloy thick plates.
[0006] In a first aspect, the present invention provides a method for preparing a high-yield titanium alloy thick plate, comprising the following steps: S1. Provide titanium alloy slab blanks, and perform milling and edge rounding treatment on the surface of the slab blanks; S2. Apply an anti-oxidation coating to the surface and edges of the slab, and after it dries, heat it and perform the first hot rolling cycle. The hot rolling cycle includes: rolling in the direction of the original width of the slab with both longitudinal and vertical rolls, rolling with the original length of the slab as the rolling width after reversing the direction, rolling with both longitudinal and vertical rolls after reversing the direction again, rolling with vertical rolls after reversing the direction again, and then leveling the slab. S3. Cooling and surface treatment of the slab after the first hot rolling cycle; S4. Cut the surface-treated slab into N sub-slabs along the length direction; S5. Round off the cut edges of each sub-slab and apply an anti-oxidation coating. After drying, heat and perform a second hot rolling cycle. The rolling sequence steps of the second hot rolling cycle are the same as those of the first hot rolling cycle. S6. After the second hot rolling cycle, each sub-slab is cooled and then annealed. S7. After annealing, each sub-slab is cooled, surface-treated, and the head, tail, and edges are cut off to obtain N finished titanium alloy thick plates.
[0007] Furthermore, in step S1, the titanium alloy slab is of alloy type such as TA15, TC4, or TC11; the slab has a thickness of 250~500mm, a width of 1000~2000mm, and a length of 1000~2500mm; when milling the slab, the milling depth on each side is not less than 3mm; after milling, there should be no obvious defects or unmilled areas on the six surfaces of the slab, the surface roughness Ra≤1.6μm, the side curvature≤3mm / m, the flatness≤2mm / m, and the thickness difference between the slab and the plate≤3mm.
[0008] Furthermore, in step S1, the rounding of the edges includes: rounding the eight edges on the upper and lower surfaces of the slab with a radius of 8-15mm, and rounding the four vertical edges on the side of the slab with a radius of 15-30mm; after slitting in step S4, rounding the edges on the cut surface of the sub-slab with a radius of 8-15mm.
[0009] Furthermore, the thickness of the anti-oxidation coating is 0.2~0.5mm; the heating temperature in steps S2 and S5 is 20~50℃ below the corresponding titanium alloy β phase transformation point, and the heating time is the slab thickness × the heat preservation coefficient, which is 1.0~2.0; the heating furnace is a box-type electric heating furnace, and the heating equipment meets the requirements of Class IV heating equipment in the AMS 2750 standard. When the furnace reaches the set heating temperature, the heat preservation time is calculated.
[0010] Furthermore, the first hot rolling cycle in step S2 is a single-pass rolling process with a deformation of 45-50% per pass and a rolling speed of 0.6-1.5 m / s; the second hot rolling cycle in step S5 is a two-pass rolling process with a deformation of 50-55% per pass and a rolling speed of 0.6-1.5 m / s, using a four-high reversible rolling mill and a vertical rolling mill.
[0011] Furthermore, in the hot rolling cycles of steps S2 and S5, when the original width of the slab is used as the rolling width for both longitudinal and vertical rolling, the longitudinal rolling passes are 2 to 5, the deformation per pass is controlled at 3% to 15%, and the total deformation of longitudinal rolling accounts for 30% to 40% of the total deformation per hot rolling pass. The vertical rolling passes are 2, and the deformation per pass is controlled at 5 to 10 mm. When widening rolling and vertical roll rolling are performed with the original length direction of the slab as the rolling width after reversal, the number of widening rolling passes is 2 to 7, the deformation per pass is controlled at 5% to 15%, the total deformation of widening rolling accounts for 40% to 50% of the deformation per pass, and the widening ratio is controlled at 1.2 to 1.4. The number of vertical roll rolling passes is 2 to 4, and the deformation per pass is controlled at 5 to 10 mm. When reversing direction again for both forward and vertical rolling, the number of forward rolling passes is 2 to 5, the deformation per pass is controlled at 5% to 15%, and the total deformation of forward rolling accounts for 15% to 25% of the total deformation per pass. The number of vertical rolling passes is 4, and the deformation per pass is controlled at 5 to 10 mm. When finally reversing direction for vertical roll rolling, the vertical roll rolling passes are 4 times, and the deformation per pass is controlled between 5 and 10 mm.
[0012] Furthermore, the leveling temperature in the first and second hot rolling cycles is not lower than 700℃; the annealing temperature in step S6 is 700~1000℃, and the time is 2~6h.
[0013] Furthermore, the surface treatments described in steps S3 and S7 both include: peeling, local defect repair, and polishing; wherein, the surface roughness Ra after peeling is ≤3.2μm, and the surface roughness Ra after polishing is ≤1.6μm.
[0014] Furthermore, in step S4, the slab blank is cut using a saw, and the bevel of the whole slab after cutting is less than 10mm; the head, tail and edge are retained when the slab blank is cut, and N is 2~4. The length direction of the N sub-slab blanks obtained by cutting is specified to be consistent with the width direction of the slab blank before cutting, and the width direction is specified to be consistent with the length direction of the slab blank before cutting.
[0015] In a second aspect, the present invention also provides a high yield titanium alloy thick plate, wherein the titanium alloy thick plate is prepared by the preparation method described in any of the embodiments of the first aspect.
[0016] Compared with the prior art, the high yield titanium alloy thick plate preparation method provided by the present invention has the following beneficial effects: 1. By applying an anti-oxidation coating to the slab surface, the contact state between the workpiece and the rolls during hot rolling is effectively improved, reducing the risk of cracking caused by excessively rapid temperature drop on the workpiece surface and enhancing the stability of the rolling process.
[0017] 2. By implementing differentiated rounded corner design on the slab edges, the plastic flow of metal at the edges during hot rolling is rationally guided, significantly reducing stress concentration and effectively suppressing the generation of edge cracks.
[0018] 3. By rationally planning the slab size and precisely configuring the number of passes, pass deformation amount and deformation ratio of longitudinal rolling, widening rolling and vertical rolling in each rolling cycle, the uniformity of workpiece deformation is significantly improved, the tongue length is effectively controlled, the free expansion of the edge is restricted, and the material loss is reduced while optimizing the plate shape.
[0019] In summary, this method can eliminate the head and tail cutting processes after the first rolling and significantly reduce the cutting loss after the second rolling, thereby increasing the rolling yield of titanium alloy thick plates to over 85% and shortening the processing cycle by 1 to 2 days. It successfully solves the problems of low yield and long production cycle in traditional rolling processes and can fully meet the current market demand for efficient and low-cost production of titanium alloy thick plates. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a flowchart illustrating the titanium alloy thick plate preparation process in a specific embodiment of the present invention. Figure 2 This is a schematic diagram of the titanium alloy thick plate rolling process in a specific embodiment of the present invention. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.
[0023] The method of the present invention is mainly applicable to the rolling production of high-strength, low-plasticity titanium alloy thick plates (such as TA15, TC4, TC11 and other titanium alloy thick plates) with finished product specifications ranging from 60 to 150 mm in thickness, 1000 to 2500 mm in width, and 2000 to 5000 mm in length.
[0024] See Figure 1 and Figure 2 The method for preparing high-yield titanium alloy thick plates provided by this invention specifically includes the following steps: Step S1: Slab selection.
[0025] Step S2: Mill the surface of the slab.
[0026] Step S3: Round the edges of the slab.
[0027] Step S4: Apply a coating evenly to the surface and edges of the slab.
[0028] Step S5: After the coating is completely dry, the slab is placed into the heating furnace for heating.
[0029] Step S6: After the heat preservation time reaches the process requirements, the slab is taken out of the furnace for hot rolling.
[0030] Step S7: Roll the slab lengthwise with the width of the slab as the standard, and then roll it with vertical rolls.
[0031] Step S8: Change the direction of the slab, roll it to the width of the slab length, and then roll it with vertical rolls.
[0032] Step S9: Change the direction of the slab, roll it in the direction of the slab width, and then roll it with vertical rolls.
[0033] Step S10: Change the direction of the slab and roll it with the width of the vertical rolls as the length of the slab.
[0034] Step S11: Flatten the surface of the slab to make the slab straight.
[0035] Step S12: Slab cooling.
[0036] Step S13: Peel the skin off the upper and lower surfaces of the slab.
[0037] Step S14: Grind local defects on the upper and lower surfaces of the slab.
[0038] Step S15: Polish the upper and lower surfaces of the slab.
[0039] Step S16: Divide the slab length into N equal parts to obtain N sub-slabs.
[0040] Step S17: Repeat step S3 for each of the N sub-slabs.
[0041] Step S18, and repeat step S4 for each of the N sub-slabs.
[0042] Step S19, and repeat step S5 for each of the N sub-slabs.
[0043] Step S20 and N sub-slabs are repeated from step S6.
[0044] Step S21, and N sub-slabs are each repeated from step S7.
[0045] Step S22, and N sub-slabs are each repeated from step S8.
[0046] Step S23, and N sub-slabs are each repeated from step S9.
[0047] Step S24, and repeat step S10 for each of the N sub-slabs.
[0048] Step S25, and N sub-slabs are each repeated from step S11.
[0049] Step S26: Repeat step S12 for each of the N sub-slabs.
[0050] Step S27: N sub-slabs are loaded into the annealing furnace in batches for annealing treatment.
[0051] Step S28, and repeat step S12 for each of the N sub-slabs.
[0052] Step S29, and repeat step S13 for each of the N sub-slabs.
[0053] Step S30 and N sub-slabs are repeated from step S14.
[0054] Step S31, and N sub-slabs are each repeated from step S15.
[0055] Step S32: Cut the ends and edges of N sub-board blanks to obtain N finished boards.
[0056] In an optional embodiment of the present invention, the alloy type of the slab in step S1 is a high-strength, low-plasticity titanium alloy (such as TA15, TC4, TC11, etc.). The slab is a black-skinned forged slab forged using a high-speed forging mill. The slab dimensions are in the range of 250~500mm (thickness) × 1000~2000mm (width) × 1000~2500mm (length).
[0057] In addition, the milling depth of the slab in step S2 shall not be less than 3 mm on each side. After milling, there should be no obvious defects or unmilled areas on the six surfaces of the slab, the surface roughness Ra≤1.6μm, the side curvature≤3mm / m, the unevenness≤2mm / m, and the thickness difference with the slab≤3mm.
[0058] In step S3, the slab edges consist of eight edges on the top and bottom surfaces and four edges on the sides. The fillet radius of the eight edges on the top and bottom surfaces is 8-15 mm; the fillet radius of the four edges on the sides is 15-30 mm.
[0059] More specifically, the coating described in step S4 is an antioxidant coating, and the coating thickness is controlled at 0.2~0.5mm.
[0060] It is understood that the heating furnace mentioned in step S5 above is a box-type electric heating furnace, and the heating equipment meets the requirements of Class IV heating equipment in the AMS2750 standard. When the furnace is filled to the set temperature, the holding time is calculated. The heating temperature is 20~50℃ below the alloy's β-phase transformation point, and the heating time is the slab thickness × holding coefficient (1.0~2.0).
[0061] Furthermore, the hot rolling in step S6 is a single-pass hot rolling. The deformation amount in the single-pass hot rolling is controlled at 45~50%, the rolling speed is 0.6-1.5m / s, and the equipment used is a four-high reversible rolling mill and a vertical rolling mill.
[0062] It should be noted that in step S7, the number of passes for the forward rolling is 2 to 5, the deformation per pass is controlled at 3% to 15%, and the total deformation per forward rolling accounts for 30% to 40% of the total deformation per pass; the number of passes for the vertical rolling is 2, and the deformation per pass is controlled at 5 to 10 mm.
[0063] In step S8, the number of widening rolling passes is 2 to 7, the deformation per pass is controlled at 5% to 15%, the total deformation of widening rolling accounts for 40% to 50% of the deformation per pass, and the widening ratio is controlled at 1.2 to 1.4; the number of vertical roll rolling passes is 2 to 4, and the deformation per pass is controlled at 5 to 10 mm.
[0064] In step S9, the number of forward rolling passes is 2 to 5, and the deformation per pass is controlled at 5% to 15%. The total deformation per forward rolling pass accounts for 15% to 25% of the total deformation per pass. The number of vertical rolling passes is 4, and the deformation per pass is controlled at 5 to 10 mm.
[0065] In the final step S10, the vertical roll rolling process consists of 4 passes, with the deformation per pass controlled between 5 and 10 mm.
[0066] Furthermore, the slab surface leveling in step S11 is carried out on a four-roll reversible rolling mill, with a surface leveling temperature of not less than 700°C and a surface leveling speed of not more than 1 m / s.
[0067] The slab cooling in step S12 is carried out on a cooling bed, and it can only be transferred to the next process when it is cooled to below 300°C.
[0068] In one optional embodiment of the present invention, the slab peeling in step S13 is performed using a surface grinder. After peeling, the surface roughness of the slab Ra ≤ 3.2 μm, and the thickness removal amount depends on the surface quality of the rolled piece, ranging from 0.3 mm to 2 mm.
[0069] More specifically, the local defect repair of the slab described in step S14 is carried out using a hand-held grinder, with a grinding depth-to-width ratio ≤1:10, and the surface roughness of the repaired area ≤3.2μm.
[0070] In step S15, the slab polishing is performed using a surface grinder, resulting in a surface roughness Ra ≤ 1.6 μm. In step S16, the slab slitting is performed using a saw, resulting in a cut bevel of less than 10 mm. During slitting, the head, tail, and edges are retained. The value of N is 2~4. The length direction of the N sub-slabs obtained from the slitting is defined as being consistent with the width direction of the original slab, and the width direction is defined as being consistent with the length direction of the original slab. In step S17, the edges refer to the edges on the cut surfaces of the sub-slabs, with a fillet radius of 8-15 mm.
[0071] It should also be noted that the hot rolling in step S20 is a two-stage hot rolling. The deformation amount of the two-stage hot rolling is controlled at 50-55%, the rolling speed is 0.6-1.5 m / s, and the equipment used is a four-high reversible rolling mill and a vertical rolling mill.
[0072] The slab surface leveling (straightening) in step S25 is carried out on a hot straightening machine, with a straightening temperature of not less than 700℃ and a straightening speed of not more than 1m / s.
[0073] Furthermore, the annealing furnace mentioned in step S27 is a roller hearth heat treatment furnace, and the heating equipment meets the requirements of Class IV heating equipment in the AMS 2750 standard. The furnace is charged to a preheated temperature. When the furnace temperature reaches the process-set heating temperature, the holding time is calculated, and the furnace is removed after the holding time meets the process requirements. The annealing temperature is 700~1000℃, and the annealing time is 2~6 hours.
[0074] The equipment used for cutting the sheet metal in step S32 is a waterjet cutter or a saw. Several specific examples will be used to further illustrate this below. Example 1
[0075] A method for preparing a high-yield TC4 titanium alloy thick plate includes the following steps: Step S1: Select a TC4 titanium alloy black-skinned forged slab with dimensions of 260mm (thickness) × 1070mm (width) × 1100mm (length). The measured β-phase transformation point of the alloy is 995℃.
[0076] Step S2: Mill all six sides of the slab. The finished slab dimensions are 250mm (thickness) × 1050mm (width) × 1060mm (length). The slab surface roughness Ra≤1.6μm, side curvature≤3mm / m, unevenness≤2mm / m, and thickness difference between the slab and the slab ≤3mm.
[0077] Step S3: Round the edges of the milled slab, with the rounding radius of the eight edges on the upper and lower surfaces being 10mm and the rounding radius of the four edges on the side being 20mm.
[0078] Step S4: Apply an anti-oxidation coating evenly to all six sides and edges of the slab, with a coating thickness of 0.3 mm.
[0079] Step S5: After the coating is completely dry, load the slab into a box-type electric heating furnace for heating at 960℃ for 350 minutes, with a heat preservation coefficient of 1.4. Once the furnace temperature reaches the process-set heating temperature, begin calculating the heat preservation time.
[0080] Step S6: After the holding time reaches the process requirements, the material is removed from the furnace and subjected to a single-fire hot rolling. The deformation amount in the single-fire hot rolling is 49.8%, and the equipment used is a four-high reversible rolling mill and a vertical rolling mill.
[0081] Step S7: Roll the slab through three passes with a width of 1050mm, with a pass reduction of 250→235→220→204mm; then roll it through two passes with a vertical roll, with a pass deformation of 5mm.
[0082] Step S8: Change the slab orientation and roll it for 3 passes with the slab length as the width to widen the slab to 1400mm, with a width ratio of about 1.33. The pass reduction is set to 204→190→170→153mm. Then roll it for 2 passes with a pass deformation of 8mm.
[0083] Step S9: Reverse the slab direction and roll it in the same direction as the slab width for two passes, with a pass reduction of 153→138→125.5mm; then roll it in the vertical roll for four passes, with a pass deformation of 10mm.
[0084] Step S10: Change the direction of the slab and roll it for 4 passes with the width of the vertical roll as the length of the slab. The deformation amount per pass is 10mm.
[0085] Step S11: Use a four-roll reversible rolling mill to flatten the surface of the slab and make the slab straight.
[0086] Step S12: The slab is cooled on a cooling bed until it reaches below 300°C before being transferred to the next process.
[0087] Step S13: Use a surface grinder to peel off the outer and inner surfaces of the slab. After peeling, the surface roughness Ra of the slab is ≤3.2μm, and the thickness removal is 0.5mm.
[0088] Step S14: Local defects on the upper and lower surfaces of the slab are repaired using a handheld grinder. The grinding depth-to-width ratio is ≤1:10, and the surface roughness of the repaired area is ≤3.2μm.
[0089] Step S15: Polish the upper and lower surfaces of the slab using a surface grinder. After polishing, the surface roughness Ra of the slab is ≤1.6μm.
[0090] Step S16: Divide the slab length into two equal parts to obtain two sub-slabs. The dimensions of the sub-slabs after division are 125mm (thickness) × 770mm (width) × 1400mm (length).
[0091] Step S17: Round the edges on the cut surface of the sub-slab with a radius of 10mm.
[0092] Step S18: Apply an anti-oxidation coating evenly to all six sides and edges of the sub-slab, with a coating thickness of 0.3 mm.
[0093] Step S19: After the coating on the sub-slab is completely dry, it is placed in a box-type electric heating furnace for heating at 960℃ for 150 minutes, with a heat preservation coefficient of 1.2. The furnace is loaded at the set temperature, and the heat preservation time is calculated starting when the furnace temperature reaches the process-set heating temperature.
[0094] Step S20: After the slab has been held at the required temperature for the specified time, it is removed from the furnace and subjected to a second hot rolling process. The deformation during the second hot rolling is 50.4%, and the equipment used is a four-high reversible rolling mill and a vertical rolling mill.
[0095] Step S21: The sub-slab is rolled in two passes with a width of 770mm, and the pass reduction is set to 125→110→100mm; then it is rolled in two passes with vertical rolls, and the deformation amount per pass is 5mm.
[0096] Step S22: Reverse the direction of the sub-slab and roll it for 3 passes with the slab length as the width to widen the slab width to 1040mm, with a width ratio of about 1.35. The pass reduction is set to 100→90→80→74mm. Then, roll it for 2 passes with a pass deformation of 6mm.
[0097] Step S23: Change the direction of the sub-slab and roll it in the same width as the slab for two passes, with the pass reduction set to 74→66→61mm; then roll it with vertical rolls for four passes, with a pass deformation of 7mm.
[0098] Step S24: Change the direction of the sub-slab and roll it for 4 passes with the width of the vertical roll as the length of the slab. The deformation amount per pass is 7mm.
[0099] Step S25: Use a hot straightening machine to hot straighten the slab to make the slab straight.
[0100] Step S26: Cool the sub-slab on the cooling bed until it reaches below 300°C before transferring it to the next process.
[0101] Step S27: The sub-slab is loaded into a roller hearth heat treatment furnace for annealing. The furnace is charged to a preheated temperature. The holding time is calculated once the furnace temperature reaches the process-set heating temperature. The slab is removed from the furnace after the holding time meets the process requirements. The annealing temperature is 800℃, and the annealing time is 2 hours.
[0102] Step S28: Cool the sub-slab on the cooling bed until it reaches below 300°C before transferring it to the next process.
[0103] Step S29: Use a surface grinder to peel the upper and lower surfaces of the slab. After peeling, the surface roughness Ra of the slab is ≤3.2μm, and the thickness removal is 1mm.
[0104] Step S30: Use a handheld grinder to grind the local defects on the upper and lower surfaces of the slab. The grinding depth-to-width ratio is ≤1:10, and the surface roughness of the ground area is ≤3.2μm.
[0105] Step S31: Polish the upper and lower surfaces of the slab using a surface grinder. After polishing, the surface roughness Ra of the slab is ≤1.6μm.
[0106] Step S32: Use a water jet cutter to cut the ends and edges of the two sub-slabs to obtain two finished TC4 titanium alloy plates. The dimensions of the finished plates are 60mm (thickness) × 1000mm (width) × 2000mm (length). Finally, the yield of the annealed 60mm thick TC4 titanium alloy plate from the blank to the finished plate is 86.3%. Example 2
[0107] A method for preparing a high-yield TA15 titanium alloy thick plate includes the following steps: Step S1: Select a TA15 titanium alloy black-skinned forged slab with dimensions of 420mm (thickness) × 1590mm (width) × 2100mm (length). The measured β-phase transformation point of the alloy is 990℃.
[0108] Step S2: Mill all six sides of the slab. The finished slab dimensions are 410mm (thickness) × 1570mm (width) × 2080mm (length). The slab surface roughness Ra≤1.6μm, side curvature≤3mm / m, unevenness≤2mm / m, and thickness difference between the slab and the slab ≤3mm.
[0109] Step S3: Round the edges of the milled slab, with the rounding radius of the eight edges on the upper and lower surfaces being 10mm and the rounding radius of the four edges on the side being 20mm.
[0110] Step S4: Apply an anti-oxidation coating evenly to all six sides and edges of the slab, with a coating thickness of 0.3 mm.
[0111] Step S5: After the coating is completely dry, load the slab into a box-type electric heating furnace for heating at 960℃ for 656 minutes, with a heat preservation coefficient of 1.6. Once the furnace temperature reaches the process-set heating temperature, begin calculating the heat preservation time.
[0112] Step S6: After the holding time reaches the process requirements, the material is removed from the furnace and subjected to a single-fire hot rolling. The deformation amount in the single-fire hot rolling is 48.8%, and the equipment used is a four-high reversible rolling mill and a vertical rolling mill.
[0113] Step S7: Roll the slab through four passes with a width of 1570mm, with the pass reduction set to 410→395→375→355→340mm; then roll it through two passes with vertical rolls, with a pass deformation of 10mm.
[0114] Step S8: Change the slab direction and roll it for 5 passes with the slab length as the width to widen the slab to 2090mm, with a width ratio of about 1.33. The pass reduction is set to 340→320→300→280→265→255mm; then roll it for 2 passes with a pass deformation of 10mm.
[0115] Step S9: Change the direction of the slab and roll it in the same direction as the width of the slab for 3 passes, with the pass reduction set to 255→240→225→209.6mm; then roll it in the vertical roll for 4 passes, with a pass deformation of 10mm.
[0116] Step S10: Change the direction of the slab and roll it for 4 passes with the width of the vertical roll as the length of the slab. The deformation amount per pass is 10mm.
[0117] Step S11: Use a four-roll reversible rolling mill to flatten the surface of the slab and make the slab straight.
[0118] Step S12: The slab is cooled on a cooling bed until it reaches below 300°C before being transferred to the next process.
[0119] Step S13: Use a surface grinder to peel off the outer and inner surfaces of the slab. After peeling, the surface roughness Ra of the slab is ≤3.2μm, and the thickness removal is 0.6mm.
[0120] Step S14: Local defects on the upper and lower surfaces of the slab are repaired using a handheld grinder. The grinding depth-to-width ratio is ≤1:10, and the surface roughness of the repaired area is ≤3.2μm.
[0121] Step S15: Polish the upper and lower surfaces of the slab using a surface grinder. After polishing, the surface roughness Ra of the slab is ≤1.6μm.
[0122] Step S16: Divide the slab length into two equal parts to obtain two sub-slabs. The dimensions of the sub-slabs after division are 209mm (thickness) × 1500mm (width) × 2090mm (length).
[0123] Step S17: Round the edges on the cut surface of the sub-slab with a radius of 10mm.
[0124] Step S18: Apply an anti-oxidation coating evenly to all six sides and edges of the sub-slab, with a coating thickness of 0.3 mm.
[0125] Step S19: After the coating on the sub-slab is completely dry, it is placed in a box-type electric heating furnace for heating at 960℃ for 251 minutes, with a heat preservation coefficient of 1.2. The furnace is loaded at the set temperature, and the heat preservation time is calculated starting when the furnace temperature reaches the process-set heating temperature.
[0126] Step S20: After the slab has been held at the required temperature for the specified time, it is removed from the furnace and subjected to a second hot rolling process. The deformation during the second hot rolling process is 51.2%, and the equipment used is a four-high reversible rolling mill and a vertical rolling mill.
[0127] Step S21: The sub-slab is rolled in three passes with a width of 1500mm, and the pass reduction is set to 209→195→180→169mm; then it is rolled in two passes with vertical rolls, and the deformation amount per pass is 5mm.
[0128] Step S22: Reverse the direction of the sub-slab and roll it for 3 passes with the slab length as the width to widen the slab to 2040mm, with a width ratio of about 1.36. The pass reduction is set to 169→155→140→124mm. Then, roll it for 2 passes with a pass deformation of 8mm.
[0129] Step S23: The sub-slab is reversed and rolled in two passes with the slab width as the width, with the pass reduction set to 124→112→101mm; then it is rolled in four passes with vertical rolls, with a pass deformation of 8mm.
[0130] Step S24: Change the direction of the sub-slab and roll it for 4 passes with the width of the vertical roll as the length of the slab. The deformation amount per pass is 8mm.
[0131] Step S25: Use a hot straightening machine to hot straighten the slab to make the slab straight.
[0132] Step S26: Cool the sub-slab on the cooling bed until it reaches below 300°C before transferring it to the next process.
[0133] Step S27: Load the sub-slab into a roller hearth heat treatment furnace for annealing. Load the slab into the furnace at the set heating temperature. When the furnace temperature reaches the process-set heating temperature, begin calculating the holding time. Remove the slab from the furnace after the holding time meets the process requirements. The annealing temperature is 840℃, and the annealing time is 4 hours.
[0134] Step S28: Cool the sub-slab on the cooling bed until it reaches below 300°C before transferring it to the next process.
[0135] Step S29: Use a surface grinder to peel the upper and lower surfaces of the slab. After peeling, the surface roughness Ra of the slab is ≤3.2μm, and the thickness removal is 1mm.
[0136] Step S30: Use a handheld grinder to grind the local defects on the upper and lower surfaces of the slab. The grinding depth-to-width ratio is ≤1:10, and the surface roughness of the ground area is ≤3.2μm.
[0137] Step S31: Polish the upper and lower surfaces of the slab using a surface grinder. After polishing, the surface roughness Ra of the slab is ≤1.6μm.
[0138] Step S32: Use a water jet cutter to cut the ends and edges of the two sub-slabs to obtain two finished TA15 titanium alloy plates. The dimensions of the finished plates are 100mm (thickness) × 2000mm (width) × 3000mm (length). Ultimately, the yield of the annealed 100mm thick TA15 titanium alloy plate from the raw slab to the finished plate is 89.6%. Example 3
[0139] A method for preparing a high-yield TC11 titanium alloy thick plate includes the following steps: Step S1: Select a TC11 titanium alloy black-skinned forged slab with dimensions of 480mm (thickness) × 1630mm (width) × 2500mm (length). The measured β-phase transformation point of the alloy is 1000℃.
[0140] Step S2: Mill all six sides of the slab. The finished slab dimensions are 470mm (thickness) × 1610mm (width) × 2460mm (length). The slab surface roughness Ra≤1.6μm, side curvature≤3mm / m, unevenness≤2mm / m, and thickness difference between the slab and the slab ≤3mm.
[0141] Step S3: Round the edges of the milled slab, with the rounding radius of the eight edges on the upper and lower surfaces being 10mm and the rounding radius of the four edges on the side being 20mm.
[0142] Step S4: Apply an anti-oxidation coating evenly to all six sides and edges of the slab, with a coating thickness of 0.3 mm.
[0143] Step S5: After the coating is completely dry, load the slab into a box-type electric heating furnace for heating at 970℃ for 752 minutes, with a heat preservation coefficient of 1.6. Once the furnace temperature reaches the process-set heating temperature, begin calculating the heat preservation time.
[0144] Step S6: After the holding time reaches the process requirements, the material is removed from the furnace and subjected to a single-fire hot rolling. The deformation amount in the single-fire hot rolling is 46.6%, and the equipment used is a four-high reversible rolling mill and a vertical rolling mill.
[0145] Step S7: Roll the slab through four passes with a width of 1610mm, with the pass reduction set to 470→450→430→410→395mm; then roll it through two passes with vertical rolls, with a pass deformation of 10mm.
[0146] Step S8: Change the direction of the slab and roll it for 5 passes with the slab length as the width to widen the slab to 2150mm, with a width ratio of about 1.34. The pass reduction is set to 395→375→355→335→315→296mm; then roll it for 4 passes with a pass deformation of 10mm.
[0147] Step S9: Reverse the slab direction and roll it in the same width as the slab for 3 passes, with the pass reduction set to 296→280→265→250.4mm; then roll it with vertical rolls for 4 passes, with a pass deformation of 10mm.
[0148] Step S10: Change the direction of the slab and roll it for 4 passes with the width of the vertical roll as the length of the slab. The deformation amount per pass is 10mm.
[0149] Step S11: Use a four-roll reversible rolling mill to flatten the surface of the slab and make the slab straight.
[0150] Step S12: The slab is cooled on a cooling bed until it reaches below 300°C before being transferred to the next process.
[0151] Step S13: Use a surface grinder to peel off the outer and inner surfaces of the slab. After peeling, the surface roughness Ra of the slab is ≤3.2μm, and the thickness removal is 0.4mm.
[0152] Step S14: Local defects on the upper and lower surfaces of the slab are repaired using a handheld grinder. The grinding depth-to-width ratio is ≤1:10, and the surface roughness of the repaired area is ≤3.2μm.
[0153] Step S15: Polish the upper and lower surfaces of the slab using a surface grinder. After polishing, the surface roughness Ra of the slab is ≤1.6μm.
[0154] Step S16: Divide the slab length into 3 equal parts to obtain 3 sub-slabs. The dimensions of the sub-slabs after division are 250mm (thickness) × 1130mm (width) × 2150mm (length).
[0155] Step S17: Round the edges on the cut surface of the sub-slab with a radius of 10mm.
[0156] Step S18: Apply an anti-oxidation coating evenly to all six sides and edges of the sub-slab, with a coating thickness of 0.3 mm.
[0157] Step S19: After the coating on the sub-slab is completely dry, place it into a box-type electric heating furnace for heating at 970℃ for 350 minutes, with a heat preservation coefficient of 1.4. The furnace is loaded at the set temperature, and the heat preservation time is calculated starting when the furnace temperature reaches the process-set heating temperature.
[0158] Step S20: After the slab has been held at the required temperature for the specified time, it is removed from the furnace and subjected to a second hot rolling process. The deformation during the second hot rolling process is 50.8%, and the equipment used is a four-high reversible rolling mill and a vertical rolling mill.
[0159] Step S21: The sub-slab is rolled in three passes with a width of 1130mm, and the pass reduction is set to 250→235→215→202mm; then it is rolled in two passes with vertical rolls, and the deformation amount per pass is 5mm.
[0160] Step S22: Reverse the direction of the sub-slab and roll it for 4 passes with the slab length as the width to widen the slab width to 1540mm, with a width ratio of about 1.36. The pass reduction is set to 202→190→175→160→148mm; then roll it for 2 passes with a pass deformation of 8mm.
[0161] Step S23: Reverse the direction of the sub-slab, roll it in the same width as the slab for 2 passes, with the pass reduction set to 148→135→120.8mm; then roll it with vertical rolls for 4 passes, with a pass deformation of 8mm.
[0162] Step S24: Change the direction of the sub-slab and roll it for 4 passes with the width of the vertical roll as the length of the slab. The deformation amount per pass is 8mm.
[0163] Step S25: Use a hot straightening machine to hot straighten the slab to make the slab straight.
[0164] Step S26: Cool the sub-slab on the cooling bed until it reaches below 300°C before transferring it to the next process.
[0165] Step S27: Load the sub-slab into a roller hearth heat treatment furnace for annealing. Load the slab into the furnace at the set heating temperature. When the furnace temperature reaches the process-set heating temperature, begin calculating the holding time. Remove the slab from the furnace after the holding time meets the process requirements. The annealing temperature is 950℃, and the annealing time is 5 hours.
[0166] Step S28: Cool the sub-slab on the cooling bed until it reaches below 300°C before transferring it to the next process.
[0167] Step S29: Use a surface grinder to peel the upper and lower surfaces of the slab. After peeling, the surface roughness Ra of the slab is ≤3.2μm, and the thickness removal is 0.8mm.
[0168] Step S30: Use a handheld grinder to grind the local defects on the upper and lower surfaces of the slab. The grinding depth-to-width ratio is ≤1:10, and the surface roughness of the ground area is ≤3.2μm.
[0169] Step S31: Polish the upper and lower surfaces of the slab using a surface grinder. After polishing, the surface roughness Ra of the slab is ≤1.6μm.
[0170] Step S32: Use a water jet cutter to cut the ends and edges of the three sub-slabs to obtain three finished TA7 titanium alloy plates. The dimensions of the finished plates are 120mm (thickness) × 1500mm (width) × 3000mm (length). Ultimately, the yield of annealed 120mm thick TC11 titanium alloy plates rolled from bare slabs to finished plates is 87.0%.
[0171] In summary, this invention provides a method for preparing high-yield titanium alloy thick plates, mainly applicable to the rolling production of high-strength, low-plasticity titanium alloy thick plates with finished specifications of 60-150mm thickness, 1000-2500mm width, and 2000-5000mm length, such as TA15, TC4, and TC11 alloys. This method includes the following key process measures: First, applying an anti-oxidation coating to the slab surface to effectively inhibit surface cracking during rolling; second, implementing differentiated rounding treatment on the slab edges to reduce the risk of crack formation around the plate from the source; furthermore, optimizing the overall plate shape and reducing material waste by rationally designing the slab size and the deformation amount and ratio of each rolling pass. The preparation method proposed in this invention can effectively overcome the problems of long rolling cycle and low yield in traditional processes, significantly improve material utilization and production efficiency, and increase the rolling yield of titanium alloy thick plates from 70-80% to over 85%, which can meet the current market's urgent demand for efficient and low-cost manufacturing of titanium alloy thick plates.
[0172] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A method for preparing a high-yield titanium alloy thick plate, characterized in that, Includes the following steps: S1. Provide titanium alloy slab blanks, and perform milling and edge rounding treatment on the surface of the slab blanks; S2. Apply an anti-oxidation coating to the surface and edges of the slab, and after it dries, heat it and perform the first hot rolling cycle. The hot rolling cycle includes: rolling in the direction of the original width of the slab with both longitudinal and vertical rolls, rolling with the original length of the slab as the rolling width after reversing the direction, rolling with both longitudinal and vertical rolls after reversing the direction again, rolling with vertical rolls after reversing the direction again, and then leveling the slab. S3. Cooling and surface treatment of the slab after the first hot rolling cycle; S4. Cut the surface-treated slab into N sub-slabs along the length direction; S5. Round off the cut edges of each sub-slab and coat it with an anti-oxidation coating. After it dries, heat it and perform a second hot rolling cycle. S6. After the second hot rolling cycle, each sub-slab is cooled and then annealed. S7. After annealing, each sub-slab is cooled, surface-treated, and the head, tail, and edges are cut off to obtain N finished titanium alloy thick plates.
2. The preparation method according to claim 1, characterized in that, In step S1, the titanium alloy slab is of alloy type TA15, TC4 or TC11; the slab has a thickness of 250~500mm, a width of 1000~2000mm and a length of 1000~2500mm.
3. The preparation method according to claim 1, characterized in that, In step S1, the rounding of the edges includes: rounding the eight edges on the upper and lower surfaces of the slab with a radius of 8-15mm, and rounding the four vertical edges on the side of the slab with a radius of 15-30mm; after slitting in step S4, rounding the edges on the cut surfaces of the sub-slab with a radius of 8-15mm.
4. The preparation method according to claim 1, characterized in that, The thickness of the anti-oxidation coating is 0.2~0.5mm; the heating temperature in steps S2 and S5 is 20~50℃ below the β phase transformation point of the corresponding titanium alloy, and the heating time is the slab thickness × the heat preservation coefficient, which is 1.0~2.
0.
5. The preparation method according to claim 1, characterized in that, The first hot rolling cycle in step S2 is a single-pass rolling process with a deformation of 45-50% per pass and a rolling speed of 0.6-1.5 m / s; the second hot rolling cycle in step S5 is a two-pass rolling process with a deformation of 50-55% per pass and a rolling speed of 0.6-1.5 m / s.
6. The preparation method according to claim 1, characterized in that, In the hot rolling cycles of steps S2 and S5, when the slab is rolled in the direction of its original width as the rolling width, the number of passes for the forward rolling is 2 to 5, the deformation per pass is controlled at 3% to 15%, and the total deformation per forward rolling accounts for 30% to 40% of the total deformation per hot rolling. The number of passes for the vertical rolling is 2, and the deformation per pass is controlled at 5 to 10 mm. When widening rolling and vertical roll rolling are performed with the original length direction of the slab as the rolling width after reversal, the number of widening rolling passes is 2 to 7, the deformation per pass is controlled at 5% to 15%, the total deformation of widening rolling accounts for 40% to 50% of the deformation per pass, and the widening ratio is controlled at 1.2 to 1.
4. The number of vertical roll rolling passes is 2 to 4, and the deformation per pass is controlled at 5 to 10 mm. When reversing direction again for both forward and vertical rolling, the number of forward rolling passes is 2 to 5, the deformation per pass is controlled at 5% to 15%, and the total deformation of forward rolling accounts for 15% to 25% of the total deformation per pass. The number of vertical rolling passes is 4, and the deformation per pass is controlled at 5 to 10 mm. When finally reversing direction for vertical roll rolling, the vertical roll rolling passes are 4 times, and the deformation per pass is controlled between 5 and 10 mm.
7. The preparation method according to claim 1, characterized in that, The leveling temperature in the first and second hot rolling cycles is not lower than 700℃; the annealing temperature in step S6 is 700~1000℃ and the time is 2~6h.
8. The preparation method according to claim 1, characterized in that, The surface treatments described in steps S3 and S7 both include: peeling, local defect repair and polishing; wherein, the surface roughness Ra after peeling is ≤3.2μm, and the surface roughness Ra after polishing is ≤1.6μm.
9. The preparation method according to claim 1, characterized in that, In step S4, the slab blank is cut using a saw, and the bevel of the whole slab after cutting is less than 10mm. When cutting the slab blank, the head, tail and edge are retained. N takes the value of 2 to 4. The length direction of the N sub-slab blanks obtained by cutting is specified to be consistent with the width direction of the slab blank before cutting, and the width direction is specified to be consistent with the length direction of the slab blank before cutting.
10. A titanium alloy thick plate, characterized in that, The titanium alloy thick plate is prepared by any one of claims 1 to 9.