Large-thickness high-toughness 450HBW wear-resistant steel plate and manufacturing method thereof

Abstract

The invention relates to a large-thickness high-toughness wear-resistant steel plate and a manufacturing method thereof, and belongs to the technical field of metallurgy. The high-strength steel comprises the following elements in percentage by mass: 0.27%-0.33% of C, 0.20%-0.35% of Si, 0.80%-1.05% of Mn, 0.025%-0.045% of Al, 0.010%-0.022% of Nb, less than or equal to 0.010% of V, 0.010%-0.022% of Ti, 0.40%-0.60% of Ni, 0.70%-0.90% of Cr, 0.40%-0.60% of Mo, 0.0015%-0.0030% of B, 0.0008%-0.0030% of Ca, less than or equal to 0.010% of P, less than or equal to 0.0015% of S, less than or equal to 0.0015% of O, less than or equal to 0.0030% of N, less than or equal to 0.00010% of H and the balance of Fe. The steel plate has a microstructure of tempered troostite; the surface Brinell hardness is 420 to 480 HBW; the core hardness reaches 90% or above of the surface hardness, the percentage elongation after fracture is greater than or equal to 12%, and the Charpy impact energy at-40 DEG C is greater than or equal to 30J. And the production thickness is 120 to 150 mm.

Description

Technical Field

[0001] This invention belongs to the field of iron-based metallurgy, and specifically relates to a method for manufacturing wear-resistant steel plates. Background Technology

[0002] Wear-resistant steel plates are widely used in industries requiring high wear resistance, such as engineering machinery, coal mine transportation, artificial board, agricultural machinery, and light rail tracks. Examples include dump truck bodies, bulldozer buckets, excavator buckets, coal mine scraper conveyors, light rail turnouts, and artificial board pressure plates. With the increasing number of large and super-large engineering projects in recent years, machinery is becoming larger, leading to a growing demand for thicker wear-resistant steel plates. However, the production of thicker wear-resistant steel plates faces numerous technical challenges: First, there is the issue of hardenability in thick steel plates. The hardness gradually decreases from the surface to the core, causing a sharp reduction in equipment lifespan once the surface hardened layer is worn away. Second, with increasing thickness, especially when the thickness is ≥100mm, the risk of cracking during flame cutting increases significantly. Third, the low-temperature impact toughness of wear-resistant steel plates cannot be guaranteed with increasing thickness.

[0003] Chinese Patent Publication No. CN 110129659 A discloses a thick 450HB grade wear-resistant steel plate with a large reduction and its rolling method. The plate is subjected to quenching and tempering heat treatment, with a surface Brinell hardness of 445~453HBW and a low-temperature impact energy of ≥25J at -40℃. However, the core hardness was not studied, and the maximum thickness of the steel plate is only 100mm.

[0004] Chinese Patent Publication No. CN 110527920 A discloses an extra-thick wear-resistant steel plate of 60-80mm and its manufacturing method. The plate undergoes a heat treatment process of quenching at 900℃ followed by low-temperature tempering at 270℃. The surface hardness of the steel plate is 390-430 HBW, and the core hardness is more than 85% of the surface hardness. However, the hardness level is only 400 HBW, and low-temperature impact toughness is not guaranteed.

[0005] Chinese Patent Publication No. CN 104962823 A discloses a high-toughness, Brinell hardness-stability, extra-thick wear-resistant steel and its preparation method. The process involves quenching at 900–940℃ followed by low-temperature tempering at 200–300℃. The surface hardness of the steel plate is 450±10 HBW, and the core hardness is 435±20 HBW. After conversion, the core hardness can reach 95% or more of the surface hardness, and the impact energy at -40℃ is 30–60 J. However, the maximum thickness of the steel plate is only 100 mm.

[0006] Chinese Patent Publication No. CN 114351053 A discloses an ultrafine-grained, high-toughness, wear-resistant steel and its manufacturing method, which adopts a high-carbon, high-silicon, high-manganese, high-nickel, and high-titanium design (C: 0.32-0.40%, Si: 0.90-1.70%, Mn: 2.50-4.00%, Ni: 1.30-2.00%, Ti: 0.45-0.55%). However, the addition of excessive Si, Mn, Ni, and Ti increases the overall alloy cost, leading to higher production costs. Secondly, excessively high Mn content can exacerbate segregation at the center of the continuously cast billet, significantly increasing the likelihood of cracks in the steel plate, especially in thicker sizes, during subsequent cutting and processing. Excessively high Si content makes it difficult to remove the iron oxide scale from the surface of the rolled plate during the billet rolling process, thus affecting the surface quality of the finished steel plate. Excessively high Ti content easily combines with other elements in the steel to precipitate, significantly reducing the toughness of the steel plate. The invention employs a normalizing process at 810–850℃ followed by a medium-temperature tempering process at 250–350℃. The surface hardness of the steel plate is 467–461 HBW, and the core hardness is 448–488 HBW. The core hardness can reach 95% or more of the surface hardness, and the impact energy at -20℃ is ≥24J. However, the impact toughness at -40℃ is not guaranteed.

[0007] Chinese Patent Publication No. CN 112063917 A discloses a wear-resistant steel plate for artificial board machinery and equipment and its manufacturing method. The invention employs a process of quenching at 880–920℃ followed by low-temperature tempering at 180–220℃, resulting in a surface hardness of 400–500 HB, and a maximum plate thickness of 120 mm. However, the core hardness and low-temperature impact toughness were not investigated.

[0008] To further promote the development of thick wear-resistant steel plates in China, the maximum thickness of HBW450 wear-resistant steel plates in the new version of GB / T24186-2022 has been revised to 120mm. In addition, the latest version of this standard adds requirements for the core hardness of wear-resistant steel plates with a thickness of ≤80mm.

[0009] Therefore, current research and development on thick HBW450 wear-resistant steel plates mainly focuses on thicknesses <120mm, while relatively little research is being done on technical challenges such as reduced core hardness, low impact toughness at -40℃, and cutting cracks in thick HBW450 wear-resistant steel plates with thicknesses ≥120mm. Summary of the Invention

[0010] The technical problem to be solved by this invention is to provide a thick, high-toughness HBW450 wear-resistant steel plate and its manufacturing method, which are in contrast to the above-mentioned prior art. The wear-resistant steel plate has a microstructure of fine and uniform tempered troostite, a surface Brinell hardness of 420-480 HBW, a core hardness of 90% or more of the surface hardness, i.e., 378-432 HBW, an elongation after fracture ≥12%, and a Charpy impact energy ≥30J at -40℃.

[0011] The technical solution adopted in this invention is as follows: an HBW450 wear-resistant steel plate, the chemical composition of which, by mass percentage, is C: 0.27-0.33%, Si: 0.20-0.35%, Mn: 0.80-1.05%, Al: 0.025-0.045%, Nb: 0.010-0.022%, V: ≤0.010%, Ti: 0.010-0.022%, Ni: 0.40-0.60%, Cr: 0.70-0.90%, Mo: 0.40-0.60%, B: 0.0015-0.0030%, Ca: 0.0008-0.0030%, P: ≤0.010%, S: ≤0.0015%, O: ≤0.0015%, N: ≤0.0030%, H: ≤0.00010%, with the balance being Fe and unavoidable impurity elements.

[0012] The thickness of the HBW450 wear-resistant steel plate of this invention is 120-150mm.

[0013] The reasons for limiting the steel plate composition in this invention are explained as follows: C: The primary element determining the hardness of steel plates. Low carbon content results in low hardness, good toughness, and high weldability; conversely, high carbon content leads to complete martensitic transformation during quenching, resulting in high strength, high hardness, and good wear resistance, but reduced toughness and poor weldability. Considering the hardness, wear resistance, low-temperature toughness, and weldability of thick wear-resistant steel plates, the carbon content in this invention is specified as 0.27–0.33%.

[0014] Silicon (Si) is an effective deoxidizing element in primary steelmaking, and as a solid dissolved element in austenite and ferrite, it can improve the strength and hardness of steel plates. However, excessive content can affect the surface quality of steel plates and increase their susceptibility to cold cracking, especially in thick steel plates. Therefore, in this invention, the silicon content is controlled at 0.20–0.35%.

[0015] Mn: An element that improves the hardenability of steel plates and promotes martensitic transformation during quenching. However, when the Mn content is low, its effect is not significant, resulting in lower strength and toughness of the steel plate. Furthermore, manganese is also a major element causing center segregation in continuously cast billets; excessively high content can exacerbate center segregation and form MnS inclusions, which adversely affect the toughness and weldability of the steel plate. Therefore, the manganese content is controlled at 0.80–1.05% in this invention.

[0016] Al (Al): A strong deoxidizing element in steel. Adding or feeding a certain amount of aluminum granules or wire during the initial refining stage can effectively reduce the formation of inclusions such as oxides in molten steel, significantly improving its purity, especially for thick steel plates. Furthermore, nitrogen (N) has a strong affinity for nitrogen, eliminating the aging sensitivity caused by nitrogen. The precipitation of nitrides refines austenite grains, thereby protecting the hardenability of boron (B). In this invention, the Al content is controlled at 0.025–0.045%.

[0017] Nb / Ti: Strong carbon and nitride forming elements that pin austenite grain boundaries, inhibiting austenite grain growth during heating and significantly improving the strength and toughness of steel plates. This invention primarily controls grain size through Nb and Ti solid solution and deformation-induced precipitation. Secondly, to address the cracking problem during cutting of thick wear-resistant steel plates, this invention employs tempering at 300–400℃ after quenching to remove martensitic stress generated during quenching. This invention controls the Nb and Ti contents to be 0.010–0.022%.

[0018] V: A grain-refining element in steel, it can produce a certain precipitation strengthening effect during tempering. However, a high V content will significantly reduce the toughness and weldability of the steel plate. Therefore, in this invention, the V content is controlled to be ≤0.010%.

[0019] Ni: The most commonly used and effective element for improving the low-temperature toughness of steel plates, but alloys made from it are relatively expensive. This invention aims to improve the impact toughness of thick steel plates at -40℃ ultra-low temperature by controlling the Ni content to be 0.40-0.60%.

[0020] Cr: An effective element for improving hardenability. It can inhibit the formation of polygonal ferrite and pearlite, promote the transformation of bainite or martensite in low-temperature structures, and thus improve the strength, hardness, and wear resistance of steel plates. However, excessively high Cr content will reduce the weldability of steel plates. In this invention, the Cr content is controlled at 0.70–0.90%.

[0021] Mo: A strong carbide-forming element, it affects the diffusion rate of carbon in steel, refines the size of precipitated carbides, and thus improves resistance during medium- and high-temperature tempering, ensuring that the steel plate can maintain certain strength, hardness, and wear resistance at medium- and high-temperature stages. In this invention, the Mo content is controlled at 0.40–0.60%.

[0022] B: An effective element for hardenability in steel. Its addition is mainly to reduce the content of other expensive alloys and lower alloy costs. However, when the content exceeds 0.005%, segregation is likely to occur, forming borides, which will significantly reduce the toughness and hardenability of the steel plate. In this invention, the B content is controlled at 0.0015–0.0030%.

[0023] Ca: A major modifying element in steel inclusions, it can react with elongated MnS to form spherical CaS, altering the anisotropy of the steel and improving the overall performance of the steel plate. In this invention, the Ca content is controlled at 0.0008–0.0030%.

[0024] P / S: Harmful elements in steel that negatively impact the material's ductility and toughness. High S content easily leads to the formation of MnS inclusions, causing anisotropy in the steel plate and making it prone to delamination and cracking. This invention aims for ultra-pure steel, strictly controlling P ≤ 0.010% and S ≤ 0.0015%.

[0025] O / N / H: Harmful gaseous elements in steel. High content leads to numerous inclusions, easily causing white spots, significantly reducing the plasticity and toughness of the steel plate, and resulting in delayed-cutting cracks. In this invention, the O content is strictly controlled to ≤0.0015%; N content to ≤0.0035%; and H content to ≤0.00010%.

[0026] This invention also provides a thick, high-toughness HBW450 wear-resistant steel plate and its manufacturing method, the specific process of which is as follows. Smelting: After KR pretreatment, molten iron is smelted in an electric furnace or converter. The initial molten steel is then sent to an LF furnace for refining and composition adjustment, followed by vacuum degassing via VD or RH processes. After degassing, Ca wire is fed into the molten steel, and it is allowed to settle and softly blown with argon. To ensure the low-temperature impact toughness of thick wear-resistant steel plates, the total grade of non-metallic inclusions A, B, C, and D in the steel is controlled to be ≤2.5.

[0027] Continuous casting: The compression ratio of the continuously cast billet and the finished steel plate is ≥3. 370-450mm thick continuously cast slabs are used for low-superheat casting production. The superheat of the molten steel is controlled at 10-25℃. In the straight arc-shaped fan-shaped section, the solidification end of the continuously cast billet is subjected to heavy pressure reduction, and the amount of heavy pressure reduction is controlled between 13-19mm. The center segregation is ≤C 1.0 grade, and the center porosity is ≤1.0 grade.

[0028] Slab slow cooling: After the slab comes off the production line, it is heated and slowly cooled in the pit. The initial temperature of slow cooling is controlled at 540-660℃, the pit heating temperature is controlled at 410-510℃, and the pit heating time is 24-36 hours. After the pit heating is stopped, the continuous casting slab is slowly cooled in the pit and removed from the pit after slow cooling for ≥36 hours.

[0029] Controlled heating, rolling, and cooling process: The continuously cast billet is loaded into the heating furnace using a walking beam method. To ensure high-temperature rolling, the billet is heated to 1220–1270℃. Once the core temperature reaches the surface temperature, it is held for at least 30 minutes to ensure uniform chemical composition and mechanical properties. After exiting the heating furnace, the billet undergoes a two-stage controlled rolling process: roughing and finishing. This refines the grain size and improves the strength and toughness of thick wear-resistant steel plates. The initial rolling temperature in the roughing stage is 1030–1120℃. To ensure sufficient core deformation, rolling is primarily completed in the roughing stage. The thickness of the intermediate billet after roughing is controlled to be 1.4–1.6t, where t is the thickness of the finished steel plate. The initial rolling temperature in the finishing stage is 800–860℃. The rolled plate is then accelerated cooled by ACC (Accelerated Cooling Control), with a cooling rate controlled at 5–12℃ / s, and a final cooling temperature of 680–740℃. Refining the grain size is mainly to obtain a fine and uniform lath martensite structure for the subsequent offline quenching process, which in turn provides a good foundation for improving the low-temperature impact toughness of thick steel plates.

[0030] Offline quenching process: The steel plate after two-stage rolling undergoes offline quenching at a temperature of 900–940℃. Once the core of the steel plate reaches its surface temperature, it is held at that temperature for 60–100 minutes. To ensure the overall temperature uniformity of the steel plate, the furnace temperature is controlled with an accuracy of ±10℃.

[0031] Medium-temperature tempering process: After offline quenching, the steel plate undergoes medium-temperature tempering at 300–400℃. Once the core of the steel plate reaches its surface temperature, it is held at this temperature for 120–180 minutes. To ensure uniform temperature throughout the steel plate, the furnace temperature deviation is precisely controlled within ±10℃. After medium-temperature tempering, the steel plate develops a stable tempered martensite structure, internal stress is completely removed, and the steel plate exhibits excellent low-temperature impact toughness. Furthermore, the risk of cracking during subsequent cutting and processing of thick steel plates is significantly reduced.

[0032] Compared with the prior art, the advantages of the present invention are as follows: This invention successfully developed HBW450 wear-resistant steel plates with a maximum thickness of 150mm using the thickest 450mm continuously cast billet in China. The 120-150mm thick wear-resistant steel plates exhibit excellent cross-sectional mechanical properties, with core hardness reaching 90% or more of the surface hardness.

[0033] This invention utilizes ultra-pure steel smelting, with the total grade of non-metallic inclusions (A, B, C, D) ≤2.5. In the straight-arc fan-shaped section, heavy pressure is applied at the end of the continuous casting billet solidification, with the pressure reduction controlled between 13 and 19 mm. The continuous casting billet employs a single-pit heating and slow cooling method. Compared to traditional methods with a cover or ordinary pit slow cooling, this method ensures the continuous casting billet remains within the efficient hydrogen diffusion temperature range, resulting in sufficient hydrogen diffusion. This is particularly effective in preventing delayed cracking, especially for thick wear-resistant steel plates. The initial slow cooling temperature of the continuous casting billet is controlled at 540–660℃, the pit heating temperature is controlled at 410–510℃, and the pit heating time is 24–36 hours. After pit heating stops, the continuous casting billet cools slowly with the pit, and is removed from the pit after ≥36 hours of slow cooling.

[0034] The present invention adopts medium carbon + Cr-Mo alloying in terms of composition, which breaks the traditional production route of quenching + low temperature tempering of wear-resistant steel plates. In terms of process, it adopts medium temperature tempering at 300-400℃, which can completely remove the martensitic internal stress generated during offline quenching of steel plates, and further significantly reduce the risk of cracking during subsequent cutting and processing of thick steel plates.

[0035] The microstructure of the steel plate of this invention differs from the tempered martensite microstructure of conventional wear-resistant steel plates; it is tempered troostite. This microstructure not only possesses advantages such as high strength, high hardness, and low crack sensitivity, but also exhibits better low-temperature toughness than tempered martensite, thereby ensuring excellent impact toughness at -40℃ for thick wear-resistant steel plates.

[0036] This invention solves the key production problems commonly found in thick wear-resistant steel plates, such as a significant decrease in core hardness as the plate thickness increases, the inability to ensure low-temperature impact toughness at -40℃, and delayed cracking during cutting. In addition, the production process is stable, and it provides a direction for the production of thick wear-resistant steel plates in China. Attached Figure Description

[0037] Figure 1 This is a metallographic image (500×) of a typical microstructure at 1 / 4 thickness of the test steel in Example 1 of this invention.

[0038] Figure 2 This is a metallographic image (500×) of a typical microstructure of 1 / 2 thickness of the test steel in Example 1 of this invention. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments. The embodiments are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0040] The production process of the thick, high-toughness HBW450 wear-resistant steel plate of this invention is as follows: converter smelting - LF ladle refining - VD or RH vacuum degassing treatment - continuous casting - slow cooling of continuous casting billet - heated rolling - quenching - medium-temperature tempering.

[0041] The production method of thick, high-toughness HBW450 wear-resistant steel plate in Embodiments 1-2 of the present invention includes the following steps: (1) Smelting: The desulfurized and silicon-reduced molten iron after KR pretreatment is smelted in an electric furnace or converter. The initial molten steel is then sent to an LF furnace for refining and composition adjustment. After vacuum degassing through VD or RH process, Ca wire is fed into the molten steel and it is allowed to stand for soft blowing of argon gas. The non-metallic inclusions A, B, C, and D are all controlled to level 0.5; the smelting composition is shown in Table 1.

[0042] (2) Continuous casting: The pure molten steel obtained in step (1) is cast using a 370-450mm billet continuous casting machine with low superheat and argon protection throughout the process. The temperature of the molten steel in the tundish is controlled at 10-25℃ above the liquidus line. The solidification end of the continuously cast billet is subjected to heavy reduction, with a reduction of 13-19mm. The center segregation is ≤C 1.0 grade, and the center porosity is ≤1.0 grade. The continuous casting process parameters are shown in Table 2.

[0043] (3) Slow cooling of slab: After the continuous casting slab obtained in step (2) is cut off from the line, it is directly put into the heating pit for slow cooling. The starting temperature of slow cooling is 540-660℃, the pit heating temperature is controlled at 410-510℃, the pit heating time is 24-36h, and after the pit stops heating, the continuous casting slab is slowly cooled with the pit. After slow cooling for ≥36 hours, it is taken out of the pit.

[0044] (4) Heating, rolling and cooling process: The continuously cast billet after slow cooling in the heating pit in step (3) is loaded into the heating furnace in a step-by-step manner. The high-temperature section is heated to 1220-1270℃. When the core temperature of the billet reaches its surface temperature, heat preservation is started, and the heat preservation time is ≥30min. After the continuously cast billet exits the heating furnace, it is rolled in two stages: roughing and finishing. The initial rolling temperature of the roughing stage is 1030-1120℃. The thickness of the intermediate billet before finishing is controlled to be 1.4-1.6t, where t is the thickness of the finished steel plate. The initial rolling temperature of the finishing stage is 800-860℃. After that, the plate is accelerated cooled by ACC, and the cooling rate is controlled to be 5-12℃ / s. The final cooling temperature is 680-740℃. The heating, rolling and cooling process is shown in Table 3.

[0045] (5) Quenching: The quenching temperature of the steel plate is 900-940℃, and the furnace temperature is controlled with an accuracy of ±10℃. After the core of the steel plate reaches its surface temperature, the heat is held for 60-100 minutes. The quenching medium is water.

[0046] (6) Tempering: The quenched steel plate is tempered at a medium temperature of 300-400℃, and the furnace temperature is controlled with a deviation of ±10℃. After the core of the steel plate reaches its surface temperature, it is held for 120-180 minutes.

[0047] The specific smelting composition, heating, rolling, and heat treatment process parameters are shown in Tables 1-4. The mechanical properties of the steel plates in each embodiment are shown in Table 5.

[0048] Figure 1 The image shows the metallographic structure at 1 / 4 thickness of the test steel in Example 1. It shows a fine and uniform tempered troostite structure with fine and uniform precipitates dispersed in the ferrite matrix. Figure 2 The image shows the metallographic structure at 1 / 2 thickness of the test steel in Example 1. It is mainly tempered troostite, or with a small amount of bainite.

[0049] This invention employs ultra-pure steelmaking continuous casting, controlled rolling and cooling, offline quenching and medium-temperature tempering processes, and controls the process from multiple angles, including chemical composition design and base material microstructure, to ensure excellent mechanical properties and low crack sensitivity of the cross-section of thick wear-resistant steel plates, providing feasibility for the increasingly large-scale development of wear-resistant equipment for engineering machinery.

[0050] Table 1. Smelting composition (wt%) of thick wear-resistant steel plates in the examples

[0051] Table 2 Continuous casting process parameters

[0052] Table 3 Heating and Controlled Rolling and Cooling Process Parameters Table 4 Heat treatment process parameters Table 5 Hardness, tensile strength, and impact resistance of embodiments of the present invention .

Claims

1. An HBW450 wear-resistant steel plate, characterized in that: The elemental composition by mass percentage is as follows: C: 0.27–0.33%, Si: 0.20–0.35%, Mn: 0.80–1.05%, Al: 0.025–0.045%, Nb: 0.010–0.022%, V: ≤0.010%, Ti: 0.010–0.022%, Ni: 0.40–0.60%, Cr: 0.70–0.90%, Mo: 0.40–0.60%, B: 0.0015–0.0030%, Ca: 0.0008–0.0030%, P: ≤0.010%, S: ≤0.0015%, O: ≤0.0015%, N: ≤0.0030%, H: ≤0.00010%, with the balance being Fe and unavoidable impurities. The steel plate has a tempered troostite microstructure.

2. The HBW450 wear-resistant steel plate according to claim 1, characterized in that: Surface Brinell hardness 420~480HBW; core hardness reaches 90% or more of surface hardness, elongation after fracture ≥12%, Charpy impact energy at -40℃ ≥30J.

3. The HBW450 wear-resistant steel plate according to claim 1, characterized in that: The production thickness is 120-150mm.

4. A method for manufacturing the HBW450 wear-resistant steel plate according to claim 1, characterized in that: include, Smelting: Smelt steel according to elemental composition, and control the total grade of non-metallic inclusions A, B, C and D in the steel to ≤2.5; Continuous casting: molten steel is poured into a billet. The thickness of the billet must meet the requirement that the compression ratio with the finished steel plate is ≥3, the center segregation of the billet is ≤C1.0 grade, and the center porosity is ≤1.0 grade. Slow cooling of billet: After the billet is removed from the production line, it is heated and slowly cooled in the pit. The initial temperature of slow cooling is controlled at 540-660℃, the pit heating temperature is controlled at 410-510℃, the pit heating time is 24-36 hours, and after the pit heating is stopped, the billet is slowly cooled in the pit. It is removed from the pit after slow cooling for ≥36 hours. Heating, rolling and cooling: The billet is heated in the furnace to austenitize the microstructure and dissolve the elements. After the billet is taken out of the furnace, it is rolled in two stages of roughing and finishing to refine the grains. The initial rolling temperature of the roughing stage is 1030-1120℃. The thickness of the intermediate billet after roughing is controlled to be 1.4-1.6t, where t is the thickness of the finished steel plate. The initial rolling temperature of the finishing stage is 800-860℃. After the controlled rolling is completed, the plate is accelerated cooled by ACC with a cooling rate of 5-12℃ / s and a final cooling temperature of 680-740℃. Quenching: tempering the steel plate to form a fine and uniform lath martensite structure; Tempering: Medium-temperature tempering is used to obtain a stable microstructure dominated by tempered martensite in the steel plate.

5. The method for manufacturing HBW450 wear-resistant steel plate according to claim 4, characterized in that: In the smelting stage, after KR pretreatment, the molten iron is smelted in an electric furnace or converter. Then, the primary molten steel is sent to the LF furnace for refining and composition adjustment. After VD or RH vacuum degassing, Ca wire is fed into the molten steel and it is left to stand and softly blow argon gas.

6. The method for manufacturing HBW450 wear-resistant steel plate according to claim 4, characterized in that: During the continuous casting stage, 370-450mm thick continuous casting slabs are used for low-superheat casting production, and the superheat of the molten steel is controlled at 10-25℃; in the straight arc-shaped fan-shaped section, the continuous casting slab is subjected to heavy pressure at the end of solidification, and the amount of heavy pressure reduction is controlled between 13-19mm.

7. The method for manufacturing HBW450 wear-resistant steel plate according to claim 4, characterized in that: During the heating, rolling and cooling stages, the billet is loaded into the heating furnace in a stepping motion and heated to 1220-1270℃. When the core temperature of the billet reaches the surface temperature, heat preservation begins and the heat preservation time is ≥30min.

8. The method for manufacturing HBW450 wear-resistant steel plate according to claim 4, characterized in that: The quenching process is offline, with a quenching temperature of 900-940℃. After the core of the steel plate reaches the surface temperature, the plate is held for 60-100 minutes.

9. The method for manufacturing HBW450 wear-resistant steel plate according to claim 4, characterized in that: The tempering temperature is 300-400℃. After the core of the steel plate reaches the surface temperature, the heat preservation begins and the heat preservation time is 120-180 minutes.

10. The method for manufacturing HBW450 wear-resistant steel plate according to claim 8 or 9, characterized in that: The furnace temperature accuracy is within ±10℃.

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