Method for inhibiting rolling edge cracks of titanium alloy
By optimizing the hot rolling process parameters, the edge cracking problem in the titanium alloy rolling process was solved, the yield and comprehensive mechanical properties were improved, and the needs of high-end fields such as aerospace and deep-sea equipment were met.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUNAN HUALING LIANYUAN STEEL SPECIAL NEW MATERIAL CO LTD
- Filing Date
- 2026-04-14
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies are insufficient to effectively suppress edge cracking during the rolling process of titanium alloys, especially in thin-gauge titanium alloy materials. This affects the yield and overall mechanical properties of the products, failing to meet the high-end requirements of aerospace and deep-sea equipment.
By optimizing parameters such as the furnace exit temperature before hot rolling, the waiting position before exiting the heating furnace, the load distribution between roughing passes, the load distribution between roughing and finishing rolling, and the exit speed of finishing rolling, a detailed process flow is formulated. This includes gradually reducing the roughing reduction rate and optimizing the finishing rolling parameters in stages to ensure that the titanium alloy slab maintains a uniform temperature and reasonable deformation during the rolling process.
It significantly reduces the probability of edge cracking during the rolling process of titanium alloys, improves the product yield, and achieves a good balance between high strength and excellent plasticity, meeting the needs of high-end fields such as aerospace and deep-sea equipment.
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Figure CN122057784A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of titanium alloy rolling technology, and in particular to a method for suppressing edge cracks during titanium alloy rolling. Background Technology
[0002] Titanium alloys, due to their high specific strength and excellent corrosion resistance, have been widely used in aerospace, marine engineering, and other fields. In recent years, with the pursuit of lightweight and high reliability in aerospace equipment, and the need for marine engineering equipment to adapt to the high-pressure environment of the deep sea, higher requirements have been placed on the strength and toughness of thin-gauge titanium alloys. However, the edge cracking problem commonly encountered during titanium alloy rolling seriously affects the yield and overall mechanical properties of the product, restricting its reliable application in high-end equipment. How to improve the plastic deformation capacity and processing performance of thin-gauge titanium alloys, and reduce the probability of edge cracking during the entire rolling process, has become an urgent technical challenge to be solved in this field.
[0003] There are currently three production methods for hot rolling of titanium alloys: (1) medium plate rolling mill, which cannot cover thickness specifications below 10mm; (2) hot coil rolling mill, which can produce specifications below 10mm, but is inefficient and has surface quality problems; (3) hot continuous rolling mill, which can produce specifications below 10mm, is efficient, but has edge cracking problems.
[0004] The main reasons for edge cracking in hot-rolled titanium alloys include: (1) During the rolling heating process, titanium is highly reactive and easily reacts with oxygen, nitrogen, hydrogen, etc. in the air. At the same time, the surface structure is easily coarsened and the plasticity is reduced. In the subsequent rolling process, the surface of the titanium alloy slab is very prone to cracking; (2) The unreasonable setting of the furnace exit temperature before hot rolling. If the furnace exit temperature is too high, it will lead to an increase in the banded structure after hot rolling, which is not conducive to the performance of the finished product. If the furnace exit temperature is too low, it will lead to a lower temperature in the entire hot rolling process, which will increase the probability of edge cracking in the entire hot rolling process; (3) The waiting position before the plate exits from the heating furnace is unreasonable. If the plate is too close to the furnace door, it will draw in cold air, causing a significant drop in temperature on one side, and eventually the edge will crack during rolling. If the plate is too far from the furnace door, the plate exit time will be extended, resulting in a decrease in overall temperature and eventually edge crack during rolling. (4) The load distribution between roughing passes is unreasonable. If the reduction rate of the later pass in the low temperature section is greater than that of the previous pass, the probability of edge crack during rolling in the later pass will increase. (5) The load distribution between roughing and finishing is unreasonable. Whether it is roughing or finishing, if the load distribution is too large, the probability of edge crack in this process will increase. (6) The exit speed of finishing is unreasonable. Finishing is located after roughing and is in a relatively low temperature section. If the speed is too slow, it will aggravate the temperature drop and increase the probability of edge crack.
[0005] To address the issue of edge cracking during hot rolling, industrial processes often employ physical isolation methods. This involves coating the surface of titanium alloy slabs with an anti-oxidation coating or explosively laminating a pure titanium layer to prevent the formation of a brittle, hard layer during the heating and rolling process. Essentially, this method constructs a brittle, hard layer, thereby eliminating the risk of edge cracking caused by deformation incompatibility between the layer and the substrate. However, this method suffers from drawbacks such as high cost and long production cycles, making it unsuitable for large-scale mass production.
[0006] In existing technologies, such as CN121082717A, a method for preparing TC4 thin-gauge titanium coils by hot continuous rolling is disclosed. The heating process involves a furnace exit temperature of 950℃~980℃; a rough rolling reduction rate of 60%~85%; a rough rolling finishing temperature ≥900℃; and a rough rolling finishing thickness of 30mm~90mm. The finishing thickness is 3mm~15mm; the finishing rolling inlet temperature ≥890℃; the finishing rolling exit speed is 2.5m / s~3.5m / s; and the finishing rolling finishing temperature ≥830℃. The titanium coils obtained by this method have a tensile strength of 992MPa, a yield strength of 883MPa, and an elongation after fracture of 13.5%. Although they possess high strength, their elongation after fracture is low, indicating a poor balance between strength and plasticity. This makes it difficult to meet the stringent requirements of high-end fields such as aerospace and deep-sea equipment, which demand both high strength and toughness.
[0007] CN119634457A discloses a method for suppressing surface cracking during the rolling process of high-strength titanium alloy thick plates. This method targets surface cracking in thick plates and improves the surface plasticity and elongation during rolling through easily implemented heating and surface rolling pretreatment, thereby suppressing the formation of surface cracks. However, this method is only applicable to titanium alloy thick plates with a slab thickness of 30mm to 50mm and cannot cover thicknesses below 10mm.
[0008] CN118719799A discloses a manufacturing process for high-strength TC4 titanium alloy plates. The heating soaking zone temperature is 980℃~1050℃; the hot rolling soaking zone temperature is 1030℃~1080℃; and the final rolling temperature is ≥800℃. The first three hot rolling passes use large reductions, with a single-pass deformation of 20~30%, the intermediate passes controlling the deformation at 15~20%, and the final pass controlling the deformation at 5~10%, for a total of nine rolling passes. The finished plate thickness is 15~30mm. The titanium alloy plates produced by this process have a tensile strength ≥895MPa, a yield strength ≥830MPa, and an elongation ≥8%. However, this process involves many rolling passes, resulting in a long production cycle. The produced titanium alloy has relatively low strength and weak toughness, and it is only suitable for medium-thick titanium alloy plates with a slab thickness of 15mm~30mm, and cannot cover thicknesses below 10mm.
[0009] In summary, the existing methods for suppressing edge cracking in hot-rolled titanium alloys are insufficient to improve the plastic deformation capacity and processing performance of thin-gauge titanium alloys, and cannot reduce the probability of edge cracking during the entire rolling process. Summary of the Invention
[0010] This application is made in view of the above-mentioned problems, and its purpose is to provide a method for suppressing edge cracking in titanium alloy rolling. By controlling the furnace exit temperature before hot rolling, the waiting position before the plate exits the heating furnace, the load distribution between roughing passes, the load distribution between roughing and finishing rolling, and the exit speed of finishing rolling, the plastic deformation capacity and processing performance of thin-gauge titanium alloys are improved, and the probability of edge cracking during the entire rolling process is reduced.
[0011] To achieve the above objectives, the present invention provides the following technical solution: a method for suppressing edge cracks during titanium alloy rolling, comprising heating a titanium alloy slab, rough rolling, and finish rolling, wherein the reduction rate of the rough rolling is reduced in each pass, wherein the reduction rate of the first pass is 35% to 40%, and the final rolling temperature of the rough rolling is 970℃ to 990℃.
[0012] Furthermore, the reduction rate of the second pass of the rough rolling is 30% to 35%.
[0013] Furthermore, the reduction rate of the third pass of the rough rolling is 20% to 30%.
[0014] Furthermore, the reduction rate of the fourth pass of the rough rolling is 15% to 25%.
[0015] Furthermore, the reduction rate of the fifth pass of the rough rolling is 10% to 15%.
[0016] Furthermore, the descaling water for the first pass of the rough rolling is shut off.
[0017] Furthermore, the descaling water for the third pass of the rough rolling is shut off.
[0018] Furthermore, the descaling water for the fifth pass of the rough rolling is shut off.
[0019] Furthermore, the final rolling exit thickness of the roughing mill is 32mm to 40mm.
[0020] Furthermore, the temperature of the heating homogenization zone is 1060℃~1080℃.
[0021] Furthermore, the heating and heat preservation time is 85 min to 115 min.
[0022] Furthermore, the furnace exit temperature after heating is 1060℃~1080℃.
[0023] Furthermore, the heating process also includes stopping the slab's advance within the heating furnace before it exits the furnace, waiting for it to be unloaded.
[0024] Furthermore, the position for waiting for the slab to be unloaded is 2m to 4m away from the furnace door on the side of the slab closest to the furnace door.
[0025] Furthermore, during the finishing rolling process, the starting temperature, exit temperature, and exit speed of the finishing rolling are determined according to the target thickness h.
[0026] Furthermore, when the target thickness of the finishing mill is 3mm≤h<4mm, the starting temperature of the finishing mill is 960℃~980℃, the exit temperature of the finishing mill is 900℃~920℃, and the exit speed of the finishing mill is 10m / s~11m / s.
[0027] Furthermore, when the target thickness of the finishing mill is 4mm≤h<6mm, the starting temperature of the finishing mill is 950℃~970℃, the exit temperature of the finishing mill is 880℃~900℃, and the exit speed of the finishing mill is 8m / s~10m / s.
[0028] Furthermore, when the target thickness of the finishing mill is 6mm≤h<10mm, the starting temperature of the finishing mill is 930℃~950℃, the exit temperature of the finishing mill is 850℃~870℃, and the exit speed of the finishing mill is 5m / s~8m / s.
[0029] Furthermore, when the target thickness of the finishing mill is 3mm ≤ h < 6mm, the descaling water is turned off; when the target thickness of the finishing mill is 6mm ≤ h < 10mm, the descaling water is turned on.
[0030] Furthermore, the titanium alloy is TC4 titanium alloy.
[0031] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention optimizes the furnace exit temperature before hot rolling to avoid the problem of increased strip structure after hot rolling due to excessive furnace exit temperature, which is detrimental to the performance of finished products; and avoids the problem of edge cracking due to low temperature during the entire hot rolling process caused by excessive furnace exit temperature.
[0032] (2) By optimizing the waiting position before the furnace exits, the present invention ensures that the slab has a uniform and sufficient temperature when it exits the furnace, thereby reducing the probability of edge cracking during the rolling process.
[0033] (3) By adopting a distribution strategy of gradually reducing the reduction rate of roughing passes, especially by applying a large reduction rate (35% to 40%) in the first pass of the high-temperature section and gradually reducing the reduction rate in the third, fourth and fifth passes of the low-temperature section, the present invention effectively reduces the probability of edge cracking due to unreasonable load distribution between roughing passes and large deformation at low temperature.
[0034] (4) By optimizing the exit thickness of the roughing mill, the present invention controls it within the optimized range of 32mm to 40mm, so that neither the roughing mill nor the finishing mill is overloaded, thereby reducing the probability of edge cracks caused by unreasonable load distribution between the roughing mill and the finishing mill.
[0035] (5) In addition, the finishing rolling process of the present invention optimizes the starting temperature, exit temperature and exit speed in segments according to the product thickness. High-speed rolling of thin specifications can shorten the rolling time and reduce the temperature drop; thick specifications use a lower speed to ensure rolling stability, realize the precise matching of finishing rolling parameters with product thickness, and ultimately reduce the probability of edge cracking due to excessively low finishing rolling exit speed.
[0036] (6) The method of the present invention can significantly suppress the edge cracking problem of titanium alloy rolling, reduce the probability of rolling scrap during rolling, and increase the product yield by 2% to 3%. It can produce thin titanium alloys with a thickness of 3mm to 10mm with few or no edge cracks. The yield strength is 860MPa to 880MPa, the tensile strength is 960MPa to 990MPa, the elongation after fracture is 15% to 16%, the reduction of area is 31% to 32%, and the average grain size is 17μm to 20μm. It achieves a good balance between high strength and excellent plasticity, and can meet the stringent requirements of comprehensive mechanical properties in high-end fields such as aerospace and deep-sea equipment. Attached Figure Description
[0037] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0038] Figure 1 This is a side view of the operation of the hot-rolled surface inspection instrument taken for the titanium alloy product obtained in Specific Embodiment 1 of the present invention.
[0039] Figure 2 This is a transmission side view taken by a hot-rolled surface inspection instrument for a titanium alloy product obtained in Specific Embodiment 1 of the present invention.
[0040] Figure 3 This is a side view of the operation of the hot-rolled surface inspection instrument taken for the titanium alloy product prepared by the conventional hot rolling process in Comparative Example 1.
[0041] Figure 4 The image shows the transmission side view of the titanium alloy product prepared by conventional hot rolling process in Comparative Example 1, taken by a hot rolling surface inspection instrument. Detailed Implementation
[0042] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.
[0043] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.
[0044] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.
[0045] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
[0046] The embodiments of this application provide a method for suppressing edge cracks during the rolling of titanium alloys, comprising heating a titanium alloy slab, rough rolling, and finish rolling, wherein the reduction rate of the rough rolling is reduced in each pass, wherein the reduction rate of the first pass is 35% to 40%, and the final rolling temperature of the rough rolling is 970°C to 990°C.
[0047] In some embodiments of this application, the reduction rate of the second pass of the rough rolling is 30% to 35%.
[0048] In some embodiments of this application, the reduction rate of the third pass of the roughing roll is 20% to 30%.
[0049] In some embodiments of this application, the reduction rate of the fourth pass of the roughing mill is 15% to 25%.
[0050] In some embodiments of this application, the reduction rate of the fifth pass of the roughing mill is 10% to 15%.
[0051] During rough rolling, the temperature gradually decreases, and the plasticity gradually deteriorates. Larger deformation is applied in the high-temperature section to fully utilize the plasticity; deformation is reduced in the low-temperature section to avoid edge cracking due to decreased plasticity. The load is evenly distributed between each pass in the rough rolling stage, and the reduction rate is reduced pass by pass to avoid sudden load increases in a certain pass that could cause excessive edge stress, thus ensuring the stability of the rolling process.
[0052] In some embodiments of this application, the descaling water for the first pass of the roughing mill is turned off.
[0053] In some embodiments of this application, the descaling water for the second pass of the roughing mill is turned off.
[0054] In some embodiments of this application, the descaling water in the third pass of the roughing mill is turned off.
[0055] In some embodiments of this application, the descaling water in the fourth pass of the roughing mill is turned off.
[0056] In some embodiments of this application, the descaling water for the fifth pass of the roughing mill is turned off.
[0057] In some embodiments of this application, the descaling water is turned on during the second pass of the roughing mill.
[0058] In some embodiments of this application, the descaling water is turned on during the fourth pass of the rough rolling.
[0059] In some embodiments of this application, the final rolling exit thickness of the roughing mill is 32 mm to 40 mm.
[0060] An unreasonable load distribution between roughing and finishing mills, whether in roughing or finishing, increases the likelihood of edge cracking in this process. The final thickness at the roughing mill exit is a crucial link between roughing and finishing. When the final thickness is less than 32mm, the roughing mill bears excessive deformation, resulting in excessive load during the low-temperature stage and a high risk of edge cracking. When the final thickness is greater than 40mm, the finishing mill entrance is too thick, requiring the finishing mill to bear excessive deformation, further increasing the risk of edge cracking during the finishing stage. Maintaining a final thickness between 32mm and 40mm ensures that neither the roughing nor finishing mills are overloaded, reducing the probability of edge cracking due to an unreasonable load distribution between them.
[0061] In some embodiments of this application, the temperature of the heating homogenization zone is 1060°C to 1080°C.
[0062] When the soaking temperature is below 1060℃, the metal's fluidity is poor, making titanium alloy sheets prone to defects such as cracks during rolling, affecting their mechanical properties and processing quality. When the soaking temperature is above 1080℃, the titanium alloy sheets have larger grains, leading to more internal defects and consequently reducing the product's toughness and strength. Maintaining a soaking temperature within the range of 1060℃ to 1080℃ avoids excessively large grains in the titanium alloy sheets, preserving high toughness and strength, while also preventing edge cracking.
[0063] In some embodiments of this application, the heating and heat preservation time is 85 min to 115 min.
[0064] In some embodiments of this application, the furnace exit temperature after heating is 1060°C to 1080°C.
[0065] When the furnace exit temperature is below 1060℃, the slab will experience a sharp increase in rolling force and stress concentration at the edges during rough rolling due to the low temperature, which can easily lead to edge cracking. When the furnace exit temperature is above 1080℃, it will cause an increase in banded structure after hot rolling, which is detrimental to the performance of the finished product. Controlling the furnace exit temperature within the range of 1060℃ to 1080℃ can reduce the formation of banded structure in titanium alloy plates, improve the performance of the finished product, and reduce the probability of edge cracking during the entire hot rolling process.
[0066] In some embodiments of this application, the heating process further includes stopping the slab's advance within the heating furnace before it exits the furnace, waiting for it to be removed from the furnace.
[0067] A walking beam furnace is used to heat the slab. Before exiting the furnace, the walking beam mechanism controls the slab to stop moving forward and wait for the previous slab to be rolled out.
[0068] In some embodiments of this application, the position for waiting for the slab to be unloaded is 2m to 4m away from the furnace door on the side of the slab closest to the furnace door.
[0069] If the waiting position before the slab exits the furnace is less than 2 meters from the furnace door, cold air will be drawn in, causing a significant drop in temperature on one side and ultimately leading to edge cracking during rolling. If the distance is greater than 4 meters from the furnace door, the exit time will be prolonged, resulting in a decrease in overall temperature and also ultimately causing edge cracking during rolling. Setting the waiting position before the slab exits the furnace within 2 to 4 meters of the furnace door on the side closest to the furnace door ensures that the slab exits the furnace at a uniform and sufficient temperature, creating optimal temperature conditions for subsequent rolling and preventing edge cracking.
[0070] In some embodiments of this application, the starting temperature, exit temperature and exit speed of the finishing mill are determined according to the target thickness h during the finishing rolling process.
[0071] Different specifications of products have different rolling characteristics, such as total deformation and temperature drop rate. Segmented optimization enables precise matching of finishing rolling parameters with product thickness. By coordinating the initial rolling temperature, exit temperature, and exit speed, a suitable deformation temperature range is maintained throughout the finishing rolling process to avoid edge cracking caused by excessively low or high temperatures. At the same time, high-speed rolling of thin specifications ensures production efficiency, while low-speed rolling of thick specifications saves energy and reduces consumption, achieving an optimal balance between efficiency and energy consumption while ensuring product quality.
[0072] In some embodiments of this application, when the target thickness of the finishing mill is 3mm≤h<4mm, the starting temperature of the finishing mill is 960℃~980℃, the exit temperature of the finishing mill is 900℃~920℃, and the exit speed of the finishing mill is 10m / s~11m / s.
[0073] In some embodiments of this application, when the target thickness of the finishing mill is 4mm≤h<6mm, the starting temperature of the finishing mill is 950℃~970℃, the exit temperature of the finishing mill is 880℃~900℃, and the exit speed of the finishing mill is 8m / s~10m / s.
[0074] In some embodiments of this application, when the target thickness of the finishing mill is 6mm≤h<10mm, the starting temperature of the finishing mill is 930℃~950℃, the exit temperature of the finishing mill is 850℃~870℃, and the exit speed of the finishing mill is 5m / s~8m / s.
[0075] In some embodiments of this application, when the target thickness of the finishing mill is 3mm≤h<6mm, the descaling water is turned off; when the target thickness of the finishing mill is 6mm≤h<10mm, the descaling water is turned on, and the pressure of the descaling water is 18MPa~26MPa.
[0076] In some embodiments of this application, the titanium alloy is TC4 titanium alloy.
[0077] The method for suppressing edge cracks in titanium alloy rolling according to the present invention will be further described below with specific examples.
[0078] Example 1 This embodiment provides a method for suppressing edge cracks during titanium alloy rolling, the specific steps of which are as follows: Heating: A TC4 titanium alloy slab with a thickness H × width B × length L of 200mm × 1100mm × 6000mm is fed into a walking beam furnace. The soaking temperature in the furnace is 1065℃, the holding time is 98min, and the exit temperature is 1065℃. Before exiting the furnace, the slab is advanced by a walking beam mechanism to a position 3.5m away from the furnace door on the side closest to the door, where it stops. The slab remains in the furnace for heat preservation until the previous slab is rolled, at which point it exits the furnace for further rolling.
[0079] Rough rolling: The slab after exiting the furnace undergoes rough rolling. The reduction rates are as follows: first pass 40%, second pass 34%, third pass 28%, fourth pass 25%, and fifth pass 14%. Descaling water is shut off during each rough rolling pass. The final rolling temperature is 984℃, and the final exit thickness is 37mm.
[0080] Finish rolling: The intermediate billet after rough rolling undergoes finish rolling to a target thickness of 3.5 mm. Based on the target thickness, the start temperature for finish rolling is set to 975℃, the exit temperature to 912℃, and the exit speed to 10.6 m / s. Descaling water is shut off during finish rolling. After finish rolling, the billet is cooled by laminar flow cooling, coiled, and produced as a 3.5 mm thick TC4 titanium alloy coil.
[0081] The 3.5mm thick TC4 titanium alloy coils were inspected using a hot-rolled surface inspection instrument. Figure 3 and Figure 4 As shown, no obvious edge crack defects were found on either the operating side or the transmission side.
[0082] The TC4 titanium alloy hot-rolled coil produced by it has a yield strength of 876MPa, a tensile strength of 982MPa, an elongation after fracture of 16%, a reduction of area of 32%, and an average grain size of 18μm.
[0083] Comparative Example 1 This comparative example provides a conventional hot rolling process for titanium alloys, with the specific steps as follows: Heating: A TC4 titanium alloy slab with a thickness H × width B × length L of 200mm × 1100mm × 6000mm is fed into a walking beam furnace. The soaking temperature in the furnace is 1100℃, the holding time is 70min, and the exit temperature is 1100℃. Before exiting the furnace, the slab is advanced by a walking beam mechanism to a position 1.5m away from the furnace door on the side closest to the door, and then stops. The slab remains in the furnace awaiting rolling; it is not held at that temperature during the waiting period. Once the previous slab has been rolled, it can be removed from the furnace for further rolling.
[0084] Rough rolling: The slab after exiting the furnace undergoes rough rolling. The reduction rates are as follows: 30% for the first pass, 25% for the second, 32% for the third, 26% for the fourth, and 18% for the fifth. Descaling water is activated during each rough rolling pass. The final rolling temperature is 945℃, and the final exit thickness is 43mm.
[0085] Finish rolling: The intermediate billet after rough rolling undergoes finish rolling. The start temperature for finish rolling is 932℃, the exit temperature is 858℃, and the exit speed is 9.5m / s. Descaling water is turned on during finish rolling. After finish rolling, the billet is cooled by laminar flow and coiled to produce 3.8mm thick TC4 titanium alloy coils.
[0086] The 3.8mm thick TC4 titanium alloy coils were inspected using a hot-rolled surface inspection instrument. Figure 3 and Figure 4 As shown, obvious edge crack defects were found on both the operating side and the transmission side. The width X of the edge crack on the operating side was 15.44 mm, and the width X of the edge crack on the transmission side was 7.47 mm.
[0087] In summary, the method for suppressing edge cracks in titanium alloy rolling provided by this invention is applicable to the hot continuous rolling production of titanium alloys, especially to the production of thin-gauge coils of TC4 titanium alloy, and can stably and efficiently produce thin-gauge titanium alloys with few or no edge crack defects.
[0088] This method can effectively reduce the chance of scrap during the rolling process and increase the product yield by 2% to 3%.
[0089] The titanium alloy prepared by this method has a yield strength of 860MPa to 880MPa, a tensile strength of 960MPa to 990MPa, an elongation after fracture of 15% to 16%, a reduction of area of 31% to 32%, and an average grain size of 17μm to 20μm. It achieves a good balance between high strength and excellent plasticity, and can meet the stringent requirements for comprehensive mechanical properties in high-end fields such as aerospace and deep-sea equipment. It has high industrial practical value and broad application prospects.
[0090] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.
Claims
1. A method for suppressing edge cracks during titanium alloy rolling, characterized in that, The titanium alloy slab is heated, rough rolled, and finish rolled. The reduction rate of the rough rolling is reduced in each pass, with the reduction rate of the first pass being 35% to 40%. The final rolling temperature of the rough rolling is 970℃ to 990℃.
2. The method for suppressing edge cracks in titanium alloy rolling according to claim 1, characterized in that, The reduction rate of the second pass of the rough rolling is 30% to 35%; And / or, the reduction rate of the third pass of the rough rolling is 20% to 30%; And / or, the reduction rate of the fourth pass of the roughing mill is 15% to 25%; And / or, the reduction rate of the fifth pass of the roughing mill is 10% to 15%; And / or, the descaling water for the first pass of the roughing mill is turned off; And / or, the descaling water for the third pass of the rough rolling is turned off; And / or, the descaling water for the fifth pass of the roughing mill is turned off; And / or, the final roll exit thickness of the roughing mill is 32mm to 40mm.
3. The method for suppressing edge cracks in titanium alloy rolling according to claim 1, characterized in that, The temperature of the heating homogenization zone is 1060℃~1080℃; And / or, the heating holding time is 85 min to 115 min; And / or, the furnace exit temperature after heating is 1060℃~1080℃; And / or, the heating process further includes stopping the slab's advance within the heating furnace before it exits the furnace, waiting for it to exit.
4. The method for suppressing edge cracks in titanium alloy rolling according to claim 3, characterized in that, The position for waiting for the slab to be unloaded is 2m to 4m away from the furnace door on the side of the slab closest to the furnace door.
5. The method for suppressing edge cracks in titanium alloy rolling according to claim 1, characterized in that, During the finishing rolling process, the starting temperature, exit temperature, and exit speed of the finishing rolling are determined according to the target thickness h.
6. The method for suppressing edge cracks in titanium alloy rolling according to claim 5, characterized in that, When the target thickness of the precision rolling is 3mm ≤ h < 4mm; The initial rolling temperature of the finishing mill is 960℃~980℃, the exit temperature of the finishing mill is 900℃~920℃, and the exit speed of the finishing mill is 10m / s~11m / s.
7. The method for suppressing edge cracks in titanium alloy rolling according to claim 5, characterized in that, When the target thickness of the precision rolling is 4mm ≤ h < 6mm; The finishing rolling start temperature is 950℃~970℃, the finishing rolling exit temperature is 880℃~900℃, and the finishing rolling exit speed is 8m / s~10m / s.
8. The method for suppressing edge cracks in titanium alloy rolling according to claim 5, characterized in that, When the target thickness of the precision rolling is 6mm ≤ h < 10mm; The finishing rolling start temperature is 930℃~950℃, the finishing rolling exit temperature is 850℃~870℃, and the finishing rolling exit speed is 5m / s~8m / s.
9. The method for suppressing edge cracks in titanium alloy rolling according to claim 5, characterized in that, When the target thickness of the finishing mill is 3mm ≤ h < 6mm, the descaling water is turned off; when the target thickness of the finishing mill is 6mm ≤ h < 10mm, the descaling water is turned on.
10. The method for suppressing edge cracks in titanium alloy rolling according to any one of claims 1-9, characterized in that, The titanium alloy is TC4 titanium alloy.