Wear-resistant steel with a thickness of 30mm or more and its production methods

Abstract

This invention provides a wear-resistant steel with a thickness of 30mm or more and its production method, belonging to the field of steel rolling technology. It includes: slab continuous casting, heating, rough rolling, finish rolling, coiling, cross-cutting and leveling, and heat treatment. The total reduction rate of rough rolling is 73-76%, and the cooling water flow ratio between the upper and lower sections of the intermediate slab in rough rolling is 1:2.5-3.5; the finish rolling has 7 passes, with the cooling water flow ratio between the upper and lower sections of the stand being 1:2-3; the coiling temperature is 800-870℃, the tension is ≥5.5MPa, and slow cooling is performed in a heat preservation box after coiling. This invention breaks through the 25.4mm design limit of hot continuous rolling production lines, solves the problems of warping and coiling in ultra-thick rolling, and achieves stable production of wear-resistant steel with a thickness of 30mm or more using coils instead of plates, with a high yield.

Description

Technical Field

[0001] This invention belongs to the field of steel rolling technology, specifically relating to a wear-resistant steel with a thickness of 30mm or more and its production method. Background Technology

[0002] Wear-resistant steel is a special type of steel used under conditions of intense impact and abrasive wear. It is widely used in the manufacture of wear-resistant components in mining machinery, construction machinery, agricultural machinery, and heavy-duty vehicles. With the development of my country's equipment manufacturing industry towards larger and lighter designs, the market demand for high-strength, high-toughness wear-resistant steel plates with a thickness exceeding 30mm is increasingly strong. However, the current production of such extra-thick wear-resistant steel mainly relies on the "welded composite" method of thin plates, which faces bottlenecks such as weak weld zone performance and short fatigue life, making it difficult to meet the stringent service requirements under heavy-duty conditions.

[0003] Hot rolling production lines mainly serve thin-gauge products because their thickness limit is generally 25.4mm. When the product thickness is close to or exceeds this limit, a series of process and equipment problems are likely to occur, such as unstable rolling process, severe warping of the head and tail of the steel plate (warping head), uncontrolled tension during coiling leading to equipment damage, or slippage and uncoiling between layers of steel coil.

[0004] Therefore, there is an urgent need for a wear-resistant steel with a thickness of 30mm or more and its production method to solve the risks of uncontrolled hot rolling tension, difficulty in coiling, and uncontrolled plate shape caused by ultra-thickness in the 2250 hot continuous rolling production line of the above-mentioned commonly used technologies. Summary of the Invention

[0005] Aiming to solve the technical problems of uncontrolled hot rolling tension, high coiling difficulty, and risk of shape loss in ultra-thick (over 30mm) steel in the 2250 hot continuous rolling production line mentioned above, this invention provides a method for producing wear-resistant steel with a thickness of over 30mm through a hot continuous rolling coiling process, including the following steps: The slabs obtained from continuous casting are heated to obtain steel billets to be rolled. The steel billet to be rolled is rolled to obtain strip steel; wherein the rolling process includes roughing and finishing rolling, the total reduction rate of the roughing rolling is 73-76%, and the ratio of the upper and lower flow rates of the intermediate billet cooling water in the roughing rolling is 1:2.5-3.5; The ratio of the vertical flow rate of the cooling water between the stands of the finishing mill is 1:2-3; The strip steel is sequentially coiled and cross-cut to obtain the wear-resistant steel.

[0006] Furthermore, the slab has a thickness of 190-230 mm and a length of 9500-11300 mm.

[0007] Furthermore, the heat treatment temperature is 1240-1280℃, and the furnace time is 160-220min.

[0008] Furthermore, the initial rolling temperature of the roughing mill is 1180-1210℃, and the final rolling temperature is 1080-1110℃. The initial rolling temperature of the finishing mill is 960-1010℃, and the final rolling temperature is 900-930℃.

[0009] Furthermore, the target thickness of the finishing mill is 26-35 mm; the number of finishing mill passes is 7.

[0010] Furthermore, the total length of the strip is ≥60000mm.

[0011] Furthermore, the winding temperature is 800-870℃, the winding tension is ≥5.5MPa, and the intermediate cooling temperature is 880-890℃.

[0012] Furthermore, the steel coil obtained after coiling is subjected to a slow cooling treatment at a cooling rate of 10℃ / h-20℃ / h.

[0013] Furthermore, the wear-resistant steel is subjected to heat treatment, which includes quenching and tempering. The quenching temperature is 880-930℃, and the tempering temperature is 180-240℃.

[0014] This invention provides a wear-resistant steel with a thickness of 30 mm or more, which is prepared by the preparation method described above.

[0015] Compared with the prior art, the present invention has at least the following advantages: This invention, by optimizing rolling process parameters, successfully broke through the traditional 25.4mm thickness design limit of the 2250mm hot continuous rolling production line, and realized the stable mass production of wear-resistant steel with a thickness of more than 30mm by "replacing plate with coil".

[0016] Specifically, by controlling the total reduction rate of roughing rolling at 73-76% and combining it with seven passes of finishing rolling, an extremely high cumulative deformation is achieved, ensuring that large slabs with a thickness of up to 230mm can be successfully thinned to the target thickness. This effectively avoids the risk of excessive rolling force due to excessive deformation in a single pass. Simultaneously, by limiting the cooling water flow ratio between the upper and lower surfaces of the roughing mill intermediate slab to 1:2.5-3.5 and the cooling water flow ratio between the finishing mill stands to 1:2-3, the temperature difference and deformation behavior of the upper and lower surfaces of the rolled piece are precisely controlled. This eliminates the head warping and tail buckling phenomena that are prone to occur in ultra-thickness rolling, significantly improving the stability of the rolling process and the accuracy of slab shape control. By setting reasonable coiling temperature and coiling tension, coiling stress is adjusted as much as possible, and the coiling roll pressure is increased to ensure smooth coiling. The leveling process provides high-quality intermediate products. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a scene diagram of the 30mm thick wear-resistant steel plate being rolled in Embodiment 1 of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0021] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of the invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to the methods, devices, and materials in the embodiments of the present invention.

[0022] Among commonly used techniques, the following technical problems still exist: On the one hand, to achieve high hardness and high strength, wear-resistant steel usually uses medium carbon steel and adds alloying elements, resulting in a deformation resistance far higher than that of ordinary structural steel. During ultra-thickness rolling, the higher deformation resistance further intensifies the equipment load and makes the control of internal stress and temperature field more complex, easily leading to uneven microstructure and properties.

[0023] Based on this, the present invention solves the above problems through the synergistic effect of the following features: By using a total reduction rate of 73-76% in roughing and 7 passes in finishing to achieve high cumulative deformation, the deformation load is distributed across multiple passes, avoiding equipment overload caused by a surge in deformation resistance in a single pass. By using a cooling water flow ratio of 1:2.5-3.5 between the upper and lower surfaces of the workpiece and a cooling water flow ratio of 1:2-3 between the stands in the finishing mill, the temperature uniformity of the upper and lower surfaces of the workpiece is precisely controlled, ensuring uniform deformation in the thickness direction and reducing microstructure differences caused by temperature differences from the source. More importantly, by controlling the coiling temperature at ≥800℃ and matching it with a high tension of ≥5.5MPa, the steel plate is coiled in a high-temperature plastic state, and then slowly cooled in an insulated box. High-temperature coiling slows down the phase transformation process, allowing the surface layer and core of the steel plate to pass through the phase transformation zone at similar rates, avoiding delamination of the microstructure in the thickness direction. High tension ensures tight adhesion between the layers of the steel coil, eliminating radial temperature unevenness caused by air gap insulation. Slow cooling in the insulated box enables martensite self-tempering, full transformation of the core microstructure, and hydrogen diffusion and escape, ultimately obtaining a wear-resistant steel plate with uniform microstructure and properties in the thickness direction.

[0024] On the other hand, the winding of ultra-thick wear-resistant steel coils is another major technical bottleneck. The tension system of ordinary coilers cannot meet the winding requirements of thick plates. Excessive tension will damage the winding shaft and auxiliary winding rollers, while insufficient tension will cause the steel coil to loosen. At the same time, the elastic recovery force of the steel plate during unwinding is huge, which can easily lead to safety accidents such as the steel coil springing open or deviating. Innovative winding and locking technology is needed to ensure safety.

[0025] Based on this, the present invention solves the above problems through the synergistic effect of the following features: The coiling temperature is strictly controlled at ≥800℃. By utilizing the characteristics of steel's good plasticity and low deformation resistance at high temperatures, the elastic recovery force of the steel plate during coiling is reduced, thereby reducing the difficulty of coiling from the material's inherent level. At the same time, high-tension coiling with ≥5.5MPa is matched to provide sufficient coiling force to ensure tight adhesion between steel coil layers and avoid interlayer slippage and loose coiling caused by insufficient tension. Immediately after coiling, the steel coil is hoisted into an insulated box for slow cooling. The slow cooling eliminates the internal stress accumulated during rolling and coiling, significantly reducing the tendency of elastic recovery deformation during uncoiling and fundamentally preventing safety accidents such as steel coil bounce-out and displacement.

[0026] By employing a synergistic control of "high temperature + high tension + heat preservation and slow cooling," this invention has successfully overcome the challenge of coiling and forming ultra-thick wear-resistant steel with a thickness of 30mm or more.

[0027] Specifically, this invention provides a method for producing wear-resistant steel with a thickness of 30mm or more using a hot continuous rolling coiling process, comprising the following steps: S1. The slab obtained from continuous casting is heated to obtain a steel billet to be rolled.

[0028] In some embodiments, the slab has a thickness of 190-230 mm and a length of 9500-11300 mm.

[0029] For example, the thickness of the slab can be 190mm, 195mm, 200mm, 205mm, 210mm, 215mm, 220mm, 225mm, 230mm, and any value between such a minimum and maximum value, or a range of any two values.

[0030] For example, the length of the slab can be 9500mm, 9600mm, 9800mm, 10000mm, 10200mm, 10500mm, 10800mm, 11000mm, 11300mm, or any value between such a minimum and maximum value, or a range of any two values.

[0031] In some embodiments, the heat treatment temperature is 1240-1280°C, and the furnace time is 160-220 min.

[0032] For example, the heating temperature can be 1240℃, 1245℃, 1250℃, 1255℃, 1260℃, 1265℃, 1270℃, 1275℃, 1280℃, and any value between such a minimum and maximum value, or a range of any two values.

[0033] For example, the heating time can be 160 min, 170 min, 180 min, 190 min, 200 min, 210 min, 220 min, and any value between such a minimum and maximum, or a range of any two values.

[0034] S2. The steel billet to be rolled is subjected to rolling treatment to obtain strip steel; wherein, the rolling treatment includes rough rolling and finish rolling, the total reduction rate of the rough rolling is 73-76%, and the ratio of the upper and lower flow rates of the intermediate billet cooling water in the rough rolling is 1:2.5-3.5.

[0035] For example, the total reduction rate of roughing can be 73%, 73.5%, 74%, 74.5%, 75%, 75.5%, 76%, and any value between such a minimum and maximum value, or a range of any two values.

[0036] By combining a high reduction rate of 73-76% in rough rolling with 7 passes in finishing rolling, the cumulative deformation is distributed across multiple passes, avoiding a surge in rolling force caused by excessive deformation in a single pass. This ensures that a large slab with a thickness of 230mm can be successfully thinned to the target thickness of 30mm, while keeping the rolling force within the safe bearing range of the equipment.

[0037] Specifically, refer to the description of Example 1 and Comparative Example 1 in this application: In Example 1, the total reduction rate of rough rolling was 75.3%, which was successfully achieved; in Comparative Example 1, after the total reduction rate of rough rolling was reduced to 66%, the final rolling thickness of the finishing mill reached 34.4 mm, which did not reach the target of 30 mm, resulting in scrap steel.

[0038] This invention controls the ratio of cooling water flow rate between the upper and lower surfaces of the roughing mill intermediate billet to 1:2.5-3.5. By controlling the difference in cooling water flow rate between the upper and lower surfaces, the temperature difference between the upper and lower surfaces of the rolled piece is precisely adjusted, so that the deformation resistance of the upper and lower surfaces tends to be consistent, eliminating the head-up phenomenon caused by the temperature difference between the upper and lower surfaces during the roughing process, and ensuring that the intermediate billet smoothly enters the finishing mill.

[0039] For example, the flow rate ratio of the cooling water in the roughing intermediate billet can be 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3.0, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5, as well as any value between such a minimum and maximum value, or a range of any two values.

[0040] In some embodiments, the initial rolling temperature of the roughing roll is 1180-1210℃, and the final rolling temperature is 1080-1110℃.

[0041] For example, the roughing rolling temperature can be 1180℃, 1185℃, 1190℃, 1195℃, 1200℃, 1205℃, 1210℃, or any value between such a minimum and maximum, or a range of any two values.

[0042] For example, the roughing and finishing rolling temperatures can be 1080℃, 1085℃, 1090℃, 1095℃, 1100℃, 1105℃, 1110℃, and any value between such minimum and maximum, or a range of any two values.

[0043] In some embodiments, the number of passes in the roughing process can be 7.

[0044] In some embodiments, the initial rolling temperature of the finishing mill is 960-1010℃, and the final rolling temperature is 900-930℃.

[0045] For example, the finishing rolling temperature can be 960℃, 965℃, 970℃, 975℃, 980℃, 985℃, 990℃, 995℃, 1000℃, 1005℃, 1010℃, or any value between such a minimum and maximum, or a range of any two values.

[0046] For example, the finishing rolling temperature can be 900℃, 905℃, 910℃, 915℃, 920℃, 925℃, 930℃, or any value between such a minimum and maximum, or a range of any two values.

[0047] In some embodiments, the number of finishing passes is 7.

[0048] In some embodiments, the target thickness of the precision rolling is 26-35 mm.

[0049] For example, the target thickness of the precision rolling can be 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, or any value between such a minimum and maximum value, or a range of any two values.

[0050] In some embodiments, the ratio of the upper and lower flow rates of the cooling water between the finishing mill stands is 1:2-3.

[0051] For example, the flow ratio of the cooling water between the stands of the finishing mill can be 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3.0, as well as any value between such a minimum and maximum value, or a range of any two values.

[0052] This invention controls the flow ratio of cooling water between the upper and lower surfaces of the strip to 1:2-3. Through asymmetric cooling between the stands, the temperature difference between the upper and lower surfaces of the strip is continuously regulated, eliminating the possible head-closing phenomenon during the finishing rolling process, ensuring the stability of the strip shape during the finishing rolling process, and avoiding the steel pile-up accident caused by the strip head hitting the roller table.

[0053] Referring to the descriptions of Example 1 and Comparative Example 2 of this application, Example 1 successfully used a 1:2.5 ratio; however, after adjusting the ratio to 1:3.5 in Comparative Example 2, the strip steel lost shape control, the buckle collided with the roller conveyor, resulting in scrap steel.

[0054] In some embodiments, the total length of the strip is ≥60000 mm.

[0055] For example, the total length of the strip can be 60000mm, 61000mm, 62000mm, 63000mm, 64000mm, 65000mm, 66000mm, 67000mm, 68000mm, 69000mm, 70000mm, and any value between such a minimum and maximum value, or a range of any two values.

[0056] S3. The strip steel is sequentially coiled and transversely cut to obtain the wear-resistant steel.

[0057] In some embodiments, the winding temperature is 800-870°C, and the winding tension is ≥5.5MPa.

[0058] For example, the winding temperature can be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, or any value between such a minimum and maximum, or a range of any two values.

[0059] For example, the winding tension can be 5.5MPa, 5.6MPa, 5.7MPa, 5.8MPa, 5.9MPa, 6.0MPa, 6.1MPa, 6.2MPa, 6.3MPa, 6.4MPa, 6.5MPa, and any value between such a minimum and maximum value, or a range of any two values.

[0060] At high temperatures (≥800℃), the steel exhibits good plasticity and a reduced elastic modulus, thereby decreasing the elastic recovery force during the winding process. High tension (≥5.5MPa) provides sufficient winding force to ensure tight bonding between layers, enabling tight winding of ultra-thick steel coils and eliminating the risk of loose or scattered winding. It also reduces the tendency to spring open during unwinding.

[0061] Referring to the descriptions of Example 1 and Comparative Examples 3 and 4 of this application, Example 1 successfully achieved a winding temperature of 846°C and a tension of 5.8 MPa; Comparative Example 3 failed to wind up and was stopped due to a reduction in speed when the winding temperature was lowered to 720°C; Comparative Example 4 resulted in the steel coil breaking apart into scrap steel when the tension was reduced to 3.5 MPa.

[0062] It should be noted that the strip obtained after finishing rolling enters a cooling process, which can be laminar flow cooling, and the intermediate temperature of laminar cooling can be 880-890℃.

[0063] For example, the intermediate temperature of the cooling layer can be 880℃, 881℃, 882℃, 883℃, 884℃, 885℃, 886℃, 887℃, 888℃, 889℃, 890℃, and any value between such a minimum and maximum value, or a range of any two values.

[0064] In some embodiments, the steel coil obtained after winding may also be subjected to a slow cooling treatment, wherein the cooling rate of the slow cooling treatment is 10-20℃ / h.

[0065] In some more specific embodiments, the slow cooling treatment can be to suspend the steel coil in an insulated box for slow cooling for ≥48 hours.

[0066] By slow cooling, the surface and core of the steel plate pass through the phase transformation zone at similar rates, avoiding delamination of the microstructure in the thickness direction; at the same time, it eliminates the internal stress accumulated during rolling and coiling; thus obtaining a wear-resistant steel plate with uniform microstructure and properties in the thickness direction; and it eliminates elastic recovery deformation after uncoiling, preventing the steel coil from springing open or shifting.

[0067] Referring to the descriptions of Example 1 and Comparative Example 5 in this application, Example 1 successfully achieved slow cooling in an insulated box for 72 hours; Comparative Example 5 used air cooling (cooling rate much greater than 20℃ / h), which resulted in rapid cooling of the steel coil and failure to eliminate internal stress, making it impossible to complete the cross-cutting and leveling.

[0068] In some embodiments, the cross-cutting and leveling can be: transferring the steel coil to the cross-cutting line and leveling it into a fixed length steel plate.

[0069] In some embodiments, the wear-resistant steel after being transversely cut and leveled may also be subjected to heat treatment, the heat treatment including quenching and tempering, wherein the quenching temperature is 880-930℃ and the tempering temperature is 180-240℃.

[0070] In some embodiments, the present invention also provides a wear-resistant steel with a thickness of 30 mm or more, which is prepared by the preparation method described above.

[0071] To facilitate a further understanding of the present invention by those skilled in the art, the following examples are provided: Example 1 This embodiment provides a method for producing 30mm thick wear-resistant steel plates using a hot continuous rolling coiling process.

[0072] S1. The slab obtained from continuous casting is heated to obtain a steel billet to be rolled.

[0073] The slab thickness is 230mm and the slab length is 11000mm. The slab heating temperature is 1250℃ and the heating time is 186min.

[0074] S2. The steel billet to be rolled is rolled to obtain strip steel.

[0075] The roughing rolling temperature was 1206℃, the ratio of cooling water flow rate between the upper and lower sections of the billet during the roughing rolling process was 1:3, the roughing rolling was carried out in 7 passes, the final roughing rolling thickness was 57mm, the final roughing rolling temperature was 1098℃, and the total roughing reduction rate reached 75.3%.

[0076] The strip then enters the continuous finishing mill. The initial finishing temperature is 987℃, and the cooling water flow ratio between the stands is 1:2.5. It is rolled in 7 passes, with a final rolling temperature of 915℃ and a final rolling thickness of 30mm. After rolling, the strip undergoes laminar flow cooling, with an intermediate temperature of 882℃.

[0077] S3. The strip steel is sequentially coiled and cross-cut to obtain the wear-resistant steel. The coiling process is shown in the diagram below. Figure 1 As shown.

[0078] The coiling temperature was 846℃, and the coiling tension was controlled at 5.8MPa during the coiling process. After coiling, the steel coil was hoisted into an insulated box for slow cooling for 72 hours at a cooling rate of 12℃ / min. Then, it was transferred and leveled by a transverse cutting line to obtain steel plates of fixed length. Subsequently, quenching and tempering treatments were carried out. The quenching temperature was 900℃, and the tempering temperature was 220℃, resulting in 30mm wear-resistant steel plates.

[0079] Results: This embodiment successfully solved three major technical challenges in producing 30mm ultra-thick wear-resistant steel on a 2250mm hot strip mill line through coordinated control of process parameters throughout the entire process: (1) Shape control in ultra-thick rolling: The total reduction rate of roughing rolling is 75.3% combined with 7 passes of finishing rolling to form high cumulative deformation, which successfully reduces the thickness of the 230mm slab to 30mm and avoids single-pass overload; by using a 1:3 ratio of cooling water flow rate between the upper and lower surfaces of the roughing rolling intermediate slab and a 1:2.5 ratio of cooling water flow rate between the finishing mill stands, the temperature difference between the upper and lower surfaces of the rolled piece is precisely controlled, which completely eliminates the head warping and tail buckling phenomena that are easy to occur in ultra-thick rolling, and ensures the stability of the rolling process.

[0080] (2) Uniformity of wear-resistant steel microstructure: High-temperature rolling (rough rolling at 1206℃ and finish rolling at 987℃) reduces the deformation resistance of alloy steel; the coiling temperature of 846℃ allows the steel plate to be coiled in a high-temperature plastic state, delaying the phase transformation process and ensuring that the surface and core of the 30mm thick plate pass through the phase transformation zone at similar rates, avoiding the delamination of the microstructure in the thickness direction; after coiling, the heat preservation box is slowly cooled for 72 hours to achieve martensitic self-tempering and internal stress elimination, resulting in a wear-resistant steel plate with uniform microstructure in the thickness direction.

[0081] (3) such as Figure 1 As shown, the coiling and forming of ultra-thick steel coils: the coiling temperature of 846℃ ensures the high-temperature plasticity of the steel plate, and the matching high tension of 5.8MPa provides sufficient coiling force. The combination of the two ensures that the layers of the steel coil are tightly bonded and there is no loose coiling or uncoiling. After coiling, it is immediately hoisted into an insulated box for slow cooling for 72 hours, which effectively eliminates the internal stress accumulated during the rolling and coiling process. There are no safety accidents such as the steel coil springing open or shifting during uncoiling. The coiling and forming problem of 30mm ultra-thick wear-resistant steel has been successfully overcome.

[0082] Comparative Example 1 Compared to Example 1, all other conditions remain the same in this comparative example, except that the total reduction rate of roughing is adjusted to 66%.

[0083] Result: The thickness of the intermediate billet in the roughing mill increased, and the final thickness in the finishing mill reached 37.4 mm. The billet could not be successfully coiled, resulting in scrap steel.

[0084] Comparative Example 2 Compared to Example 1, all other conditions in this comparative example remain unchanged, except that the flow ratio of the cooling water between the finishing mill stands is adjusted to 1:3.5.

[0085] Result: The shape of the finished strip was out of control, and the strip buckle hit the roller table, resulting in scrap steel coils.

[0086] Comparative Example 3 Compared to Example 1, all other conditions in this comparative example remain unchanged, except that the winding temperature is adjusted to 720°C.

[0087] Result: After the steel strip head was inserted into the coiler, it was difficult to coil, and the coiling speed gradually decreased until the machine stopped, resulting in scrap steel.

[0088] Comparative Example 4 Compared to Example 1, all other conditions in this comparative example remain unchanged, except that the winding tension is adjusted to 3.5 MPa.

[0089] Result: After winding, the tightness of the steel coil was insufficient to resist the deformation of the steel coil, resulting in the unwinding of scrap steel.

[0090] Comparative Example 5 Compared to Example 1, all other conditions remain the same in this comparative example, except that the slow cooling of the insulated box is replaced with air cooling.

[0091] Result: The steel coil cooled quickly, the steel plate had high strength, and the internal stress was not eliminated, which led to the warping of the steel plate and the failure to meet the plate shape requirements, making it impossible to complete the cross-cutting and leveling in the subsequent process.

[0092] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for producing wear-resistant steel with a thickness of 30mm or more by hot continuous rolling and coiling process, characterized in that, Including the following steps: The slabs obtained from continuous casting are heated to obtain steel billets to be rolled. The steel billet to be rolled is rolled to obtain strip steel; wherein the rolling process includes roughing and finishing rolling, the total reduction rate of the roughing rolling is 73-76%, and the ratio of the upper and lower flow rates of the intermediate billet cooling water in the roughing rolling is 1:2.5-3.5; The ratio of the vertical flow rate of the cooling water between the stands of the finishing mill is 1:2-3; The strip steel is sequentially coiled and cross-cut to obtain the wear-resistant steel.

2. The method for producing wear-resistant steel with a thickness of 30mm or more by hot continuous rolling coiling process according to claim 1, characterized in that, The slab has a thickness of 190-230mm and a length of 9500-11300mm.

3. The method for producing wear-resistant steel with a thickness of 30 mm or more by hot continuous rolling coiling process according to claim 1, characterized in that, The heat treatment temperature is 1240-1280℃, and the furnace time is 160-220min.

4. The method for producing wear-resistant steel with a thickness of 30 mm or more by hot continuous rolling coiling process according to claim 1, characterized in that, The initial rolling temperature of the roughing mill is 1180-1210℃, and the final rolling temperature is 1080-1110℃. The initial rolling temperature of the finishing mill is 960-1010℃, and the final rolling temperature is 900-930℃.

5. The method for producing wear-resistant steel with a thickness of 30 mm or more by hot continuous rolling coiling process according to claim 1, characterized in that, The target thickness of the finishing mill is 26-35 mm; the number of finishing mill passes is 7.

6. The method for producing wear-resistant steel with a thickness of 30 mm or more by hot continuous rolling coiling process according to claim 1, characterized in that, The total length of the strip is ≥60000mm.

7. The method for producing wear-resistant steel with a thickness of 30 mm or more by hot continuous rolling coiling process according to claim 1, characterized in that, The winding temperature is 800-870℃, the winding tension is ≥5.5MPa, and the intermediate temperature of the lamination cooling is 880-890℃.

8. The method for producing wear-resistant steel with a thickness of 30 mm or more by hot continuous rolling coiling process according to claim 1, characterized in that, The steel coil obtained after winding is subjected to slow cooling treatment at a rate of 10℃ / h-20℃ / h.

9. The method for producing wear-resistant steel with a thickness of 30 mm or more by hot continuous rolling coiling process according to claim 1, characterized in that, The wear-resistant steel is subjected to heat treatment, which includes quenching and tempering. The quenching temperature is 880-930℃, and the tempering temperature is 180-240℃.

10. A wear-resistant steel with a thickness of 30 mm or more, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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