High cold-bending wear-resistant steel plate and manufacturing method thereof

Abstract

The application provides a high cold-bending wear-resistant steel plate and a manufacturing method thereof. The high cold-bending wear-resistant steel plate comprises, from the surface to the inside, a surface layer, a transition layer and a core portion in sequence. The metallographic structure of the surface layer is ferrite, and the thickness of the surface layer is 50 microns or more. The transition layer is located under the surface layer, the metallographic structure of the transition layer is a mixed structure of ferrite and tempered martensite, and the thickness of the transition layer is 50 microns or more. The metallographic structure of the core portion is tempered martensite. The total thickness of the high cold-bending wear-resistant steel plate is 4 mm or more. When the thickness of the high cold-bending wear-resistant steel plate is a, the bending diameter when 90-degree bending is performed is D, and D=na is satisfied, wherein n is 2-4. The high cold-bending wear-resistant steel plate has excellent cold-bending performance and good low-temperature impact toughness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, in particular to a high cold-bending wear-resistant steel plate and a manufacturing method thereof. BACKGROUND

[0002] When wear-resistant steel is applied to the manufacture of self-unloading vehicle compartments and mining machinery equipment as wear-resistant components, it is required to have high strength, high plasticity and good low-temperature toughness.

[0003] In the prior art, the production process of wear-resistant steel is: steelmaking-continuous casting-hot rolling-finishing-heat treatment. The wear-resistant steel after heat treatment can form a uniform tempered martensite structure on the surface. For example, in patent application No. 202210035248.6, a kind of high toughness wear-resistant steel with excellent cold bending performance and its manufacturing method is described as "the microstructure of the wear-resistant steel is martensite + residual austenite + TiC precipitated phase", "the surface hardness of the wear-resistant steel plate is 420-468HBW, the core hardness is 417-467HBW, the difference between the surface hardness and the core hardness is not more than 10HBW; the-40℃ impact energy of the wear-resistant steel plate is 44-49J; the wear-resistant steel plate is cold-bent at 90°, d=5a is qualified". The martensite structure on the surface of the wear-resistant steel makes the wear-resistant steel have good wear resistance and strength, but its cold bending performance can only meet d=5a (d is the bending radius, a is the thickness of the steel plate), which seriously limits the application range of the wear-resistant steel. And because of its poor cold bending performance, the wear-resistant components after cold bending processing are prone to micro-cracks, which makes the wear-resistant components prone to cracking and expansion during service, and even causes the wear-resistant components to break, reducing the service life of the wear-resistant steel. SUMMARY

[0004] Therefore, the present application provides a high cold-bending wear-resistant steel plate.

[0005] The present application also provides a manufacturing method of a high cold-bending wear-resistant steel plate.

[0006] According to the high cold-bending wear-resistant steel plate of the first aspect of the present application, from the surface to the inside, it includes:

[0007] a surface layer, the metallographic structure of the surface layer is ferrite, and the thickness of the surface layer is more than 50 microns;

[0008] a transition layer, the transition layer is located below the surface layer, the metallographic structure of the transition layer is a mixed structure of ferrite and tempered martensite, and the thickness of the transition layer is more than 50 microns;

[0009] a core, the metallographic structure of the core is tempered martensite;

[0010] wherein, the total thickness of the high cold-bending wear-resistant steel plate is more than 4mm;

[0011] The thickness of the high cold-bending wear-resistant steel plate is a, the bending diameter when 90° bending is D, D=a, and n is 2-4.

[0012] Further, the high cold-bending wear-resistant steel plate comprises an iron base and chemical elements with mass percentages as follows:

[0013] C: 0.190%-0.250%, Mn: 0.60%-2.0%, Si: 0.05%-1.0%, Al: 0.030%-0.080%, Cr: 0.20%-0.80%, B: 0.00050%-0.0030%, P≤0.020%, S≤0.0050%, Mo≤0.30%, W≤0.30%, and micro-alloy elements≤0.20%, the micro-alloy elements including any one or more of Nb, Ti, and V.

[0014] Further, the micro-alloy elements include: Nb: 0.010%-0.040%, Ti: 0.010%-0.050%, and V: 0.010%-0.03%.

[0015] Further, the mass percentages of the chemical elements in the high cold-bending wear-resistant steel plate satisfy:

[0016] Further, the high cold-bending wear-resistant steel plate further contains, in mass percentages, Cu≤0.40% and Ni≤0.6%.

[0017] Further, the high cold-bending wear-resistant steel plate has an impact energy of -60°C>80J, the Vickers hardness of the surface layer is <200HV, and the Vickers hardness of the core is 400-550HV.

[0018] The manufacturing method of the high cold-bending wear-resistant steel plate according to the second aspect of the present application comprises the following steps:

[0019] S1, proportioning according to the chemical element composition, then refining and casting to obtain a cast blank;

[0020] S2, hot rolling the cast blank in step S1 to obtain a hot-rolled steel plate, and the step S2 comprises:

[0021] S21, heating the cast blank to 1200-1260°C in a heating furnace and keeping the temperature for 1-3h;

[0022] S22, rolling the cast blank in step S21 by one pass or more to obtain the hot-rolled steel plate, and in the hot rolling step, the final rolling temperature is 820-900°C;

[0023] S23, cooling the hot-rolled steel plate in step S22.

[0024] S3, performing heat treatment on the hot-rolled steel plate obtained in step S2 to obtain the high cold-bending wear-resistant steel plate.

[0025] Further, the step S23 comprises:

[0026] S231, cooling the hot-rolled steel plate in step S22 to 500-600℃ at a cooling speed of 20℃ / s or higher;

[0027] S232, continuing air cooling of the hot-rolled steel plate cooled to 500-600℃ in step S231 to room temperature.

[0028] Further, the step S3 comprises:

[0029] S31, placing the hot-rolled steel plate in step S2 into a quenching furnace under a protective gas atmosphere to perform quenching treatment, the quenching temperature being 880-950℃, and after holding for 8-20min, rapidly cooling to room temperature at a cooling speed of 50-200℃ / s;

[0030] S32, performing tempering treatment on the hot-rolled steel plate in step S31, the tempering temperature being 180-250℃, and after holding for 10-40min, air cooling to room temperature.

[0031] Further, in the step S31, the oxygen content of the quenching furnace is 50-300ppm.

[0032] The above technical solution of the present application has at least one of the following beneficial effects:

[0033] 1. The high cold-bending wear-resistant steel plate according to the embodiment of the present application can form a ferrite microstructure with a thickness of 50 microns or higher on the surface layer of the high cold-bending wear-resistant steel plate through component design and optimized manufacturing process, and can effectively constrain the local necking of the transition layer under the surface layer and limit the local deformation of the transition layer and the core by using the high uniform elongation of the ferrite structure, thereby effectively improving the cold-bending performance and low-temperature impact toughness of the high cold-bending wear-resistant steel plate, the thickness of the high cold-bending wear-resistant steel plate is a, the bending diameter when 90° bending is D, and D=na is satisfied, n is 2-4, and the application range of the high cold-bending wear-resistant steel plate is expanded.

[0034] 2. The high cold-bending wear-resistant steel plate according to the embodiment of the present application can form a tempered martensite microstructure in the core through component design and optimized manufacturing process, and the Vickers hardness of the core is 400-550HV, which meets the wear resistance requirement. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The microstructure of the high cold-bending wear-resistant steel plate according to Embodiment 3 of the present application;

[0036] Figure 2 A metallographic structure of a steel plate according to Comparative Example 1 of the present application;

[0037] Figure 3 A metallographic structure of a steel plate according to Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0039] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the common meaning understood by one of ordinary skill in the art to which the present application pertains. The terms "first", "second", and similar terms used in the present application do not denote any order, quantity, or importance, but are used to distinguish different components. Similarly, the terms "one" or "a" or similar terms do not denote a quantity of one, but rather denote the presence of at least one. The terms "connected" or "coupled" or similar terms do not limit to physical or mechanical connections or couplings, but also include electrical connections or couplings, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like are used only to indicate relative positions, and when the absolute positions of the described objects are changed, the relative positions are also changed accordingly.

[0040] The high cold-bending wear-resistant steel plate of the embodiments of the present application will be described in detail first below, which comprises, from the surface to the inside, a surface layer, a transition layer and a core portion in sequence, the surface layer has a ferrite microstructure, and the thickness of the surface layer is 50 microns or more; the transition layer is located below the surface layer, the transition layer has a mixed microstructure of ferrite and tempered martensite, and the thickness of the transition layer is 50 microns or more; the core portion has a tempered martensite microstructure; wherein the total thickness of the high cold-bending wear-resistant steel plate is 4 mm or more; the thickness of the high cold-bending wear-resistant steel plate is a, the bending diameter when 90° bending is D, and D=na is satisfied, n is 2-4.

[0041] That is, the total thickness of the high cold-bending wear-resistant steel plate is more than 4mm, because the ferrite formed in the surface layer of the high cold-bending wear-resistant steel plate of the embodiment of the present application will affect the tensile strength thereof, and if the thickness of the high cold-bending wear-resistant steel plate is too small, the tensile property thereof will not meet the use requirement. The high cold-bending wear-resistant steel plate of the embodiment of the present application forms the ferrite microstructure with the thickness of more than 50 microns in the surface layer thereof, and by using the characteristic that the uniform elongation of the ferrite structure is high, the local necking of the transition layer under the surface layer can be effectively restrained, so as to limit the local deformation of the transition layer and the core, and the cold-bending property and the low-temperature impact toughness of the high cold-bending wear-resistant steel plate can be effectively improved. In addition, the tempered martensite structure formed in the core can ensure the wear resistance of the high cold-bending wear-resistant steel plate.

[0042] The high cold-bending wear-resistant steel plate of the embodiment of the present application has good cold-bending property, and when the thickness of the high cold-bending wear-resistant steel plate is a, the bending diameter is D when 90° bending is performed, and D=na is met, and n is 2-4, so that the application range of the high cold-bending wear-resistant steel plate is expanded.

[0043] Further, the high cold-bending wear-resistant steel plate comprises an iron base and the following chemical elements dispersed in the iron base: C: 0.190%-0.250%, Mn: 0.60%-2.0%, Si: 0.05%-1.0%, Al: 0.030%-0.080%, Cr: 0.20%-0.80%, Nb: 0.010%-0.040%, Ti: 0.010%-0.050%, V: 0.010%-0.03%, B: 0.00050%-0.0030%, P≤0.020%, S≤0.0050%, and at least one of Mo≤0.30%, W≤0.30%, Ni≤0.6%, and Cu≤0.4%. That is, by adding the beneficial elements C, Mn, Si, Al, Cr, Nb, Ti, V, B, Mo, W, Ni, and Cu in proportion and controlling the harmful elements P and S, the high cold-bending wear-resistant steel plate with good cold-bending property can be obtained.

[0044] Specifically, in the present application, the design principle of each chemical element in the high cold-bending wear-resistant steel plate is as follows:

[0045] C: solid solution strengthening, C is the most basic and important element in the wear-resistant steel, C can improve the strength and hardness of the steel through solid solution strengthening, and can adjust the strength, plasticity and toughness of the tempered martensite structure. The relationship between the tensile strength Rm of the low-carbon tempered martensite after heating and quenching and the mass percentage content of C is as follows: Rm=2510*C(%)+790(MPa); and the strength, plasticity and toughness of the steel can be further adjusted through tempering treatment after quenching. That is, if the content of C is too low, the tensile strength of the steel will be reduced, and if the content of C is too high, the overall carbon equivalent will be increased, which is easy to cause cracks in the steel during welding.

[0046] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained 90° cold-bending, satisfying D=(2-4)a, the mass percentage of C in the high cold-bending abrasion-resistant steel plate is controlled at 0.190%-0.250%.

[0047] Mn: Mn can increase the hardenability of the steel, reduce the transformation temperature of the steel and the critical cooling speed of the steel. But when the content of Mn is high, segregation and inclusions such as MnS are easily produced in the steel, reducing the toughness of the steel.

[0048] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained 90° cold-bending, satisfying D=(2-4)a, the mass percentage of Mn in the high cold-bending abrasion-resistant steel plate is controlled at 0.60%-2.0%.

[0049] B: B can improve the hardenability of the steel and improve the strength of the steel. But when the content of B is too high, segregation is easily produced, forming carbon borides, reducing the toughness of the steel.

[0050] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained 90° cold-bending, satisfying D=(2-4)a, the mass percentage of B in the high cold-bending abrasion-resistant steel plate is controlled at 0.00050%-0.0030%.

[0051] Micro-alloying element: the micro-alloying element can be at least one of Nb, Ti and V, the micro-alloying element can form nanoscale precipitates with C, N and other elements, inhibit the growth of austenite grains during heating, refine the grains, and improve the plasticity and toughness of the steel plate.

[0052] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained 90° cold-bending, satisfying D=(2-4)a, the mass percentage of the micro-alloying element in the high cold-bending abrasion-resistant steel plate is ≤0.20%.

[0053] Si: Si is an oxygen-loving element, which can accelerate the expansion of O atoms in the steel plate during heating, make C in the surface structure react with O, and reduce the C content in the surface structure. During cooling, it can increase the energy when austenite transforms into ferrite during heating, and accelerate the ferrite phase change. But when the content of Si is too high, red scale is easily produced, reducing the plasticity and toughness of the steel.

[0054] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained a ferrite surface layer with a thickness of 50 microns or more, the mass percentage of Si in the high cold-bending abrasion-resistant steel plate is controlled at 0.05%-1.0%.

[0055] Al: Al is an oxygen element, which can accelerate the diffusion of oxygen atoms in the steel plate during heating, react C and O in the surface structure, and reduce the carbon content in the surface structure. During cooling, it can increase the energy of austenite to ferrite transformation during heating, and accelerate the ferrite phase change. However, if the content of Al is too high, it will affect the welding quality.

[0056] Therefore, in the present application, for the purpose of obtaining a ferrite surface layer with a thickness of 50 microns or more, the mass percentage of Al in the high cold bending wear-resistant steel plate is controlled at 0.030% to 0.080%.

[0057] Cr: Cr can improve the hardenability of steel, and has the effect of resisting high temperature oxidation, reducing surface burning during heating, and improving the tempering stability of steel. If the content of Cr is too high, it will damage the low temperature toughness, impact load fracture resistance, bending cold workability of the steel plate, and also damage the weldability of the steel plate.

[0058] Therefore, in the present application, for the purpose of obtaining a ferrite surface layer with a thickness of 50 microns or more, the mass percentage of Cr in the high cold bending wear-resistant steel plate is controlled at 0.20% to 0.80%.

[0059] Mo: Mo element can refine the grain, improve the strength, toughness and hardenability of steel. If the content of Mo is too high, it will inhibit the diffusion of carbon in the near-surface structure of the steel plate during heating, and the hardenability is too high, which will accelerate the transformation of austenite to martensite during quenching and cooling, and reduce the toughness of the steel.

[0060] Therefore, in the present application, for the purpose of obtaining a ferrite surface layer with a thickness of 50 microns or more, Mo can be added to improve the strength, toughness and hardenability of steel, preferably, the mass percentage of Mo in the high cold bending wear-resistant steel plate is ≤0.30%.

[0061] W: W can improve the hardenability of steel, form carbide particles during tempering, and has obvious anti-tempering softening effect. However, if the content of W is too high, it will inhibit the diffusion of carbon in the steel plate, making the hardenability of the steel too high, which will accelerate the transformation of austenite to martensite during quenching and cooling.

[0062] Therefore, in the present application, for the purpose of obtaining a ferrite surface layer with a thickness of 50 microns or more, W can be added to improve the hardenability of steel, preferably, the mass percentage of W in the high cold bending wear-resistant steel plate is ≤0.3%.

[0063] P and S, P and S are harmful elements in wear-resistant steel, P is an impurity brought into steel from pig iron, P can be completely dissolved in ferrite, reducing the plasticity and toughness of steel; S is an impurity brought into steel from pig iron and fuel, sulfides formed during the production of steel will reduce the mechanical properties of steel, and hot working fiber structure will be formed during rolling.

[0064] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained 90° cold-bending, the mass percentage of P in the high cold-bending abrasion-resistant steel plate is ≤0.020%, and the mass percentage of S in the high cold-bending abrasion-resistant steel plate is ≤0.0050%.

[0065] Further, the micro-alloying elements include: Nb: 0.010%-0.040%, Ti: 0.010%-0.050%, and V: 0.010%-0.03%. Specifically, in the present application, the design principle of each micro-alloying element in the high cold-bending abrasion-resistant steel plate is as follows:

[0066] Nb: Nb can improve the strength and toughness of the steel through grain refinement.

[0067] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained 90° cold-bending, the mass percentage of Nb in the high cold-bending abrasion-resistant steel plate is controlled to be 0.010%-0.040%.

[0068] Ti: Ti is one of the strong carbide-forming elements.

[0069] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained 90° cold-bending, the mass percentage of Ti in the high cold-bending abrasion-resistant steel plate is controlled to be 0.010%-0.050%.

[0070] V: In the steel, V mainly exists in the form of carbide. Its main role is to refine the structure and grain of the steel, and to reduce the strength and toughness of the steel.

[0071] Therefore, in the present application, for the high cold-bending abrasion-resistant steel plate to be obtained 90° cold-bending, the mass percentage of V in the high cold-bending abrasion-resistant steel plate is controlled to be 0.010%-0.03%.

[0072] Further, the mass percentage of the chemical elements in the high cold-bending abrasion-resistant steel plate satisfies: Si and Al are both oxygenophilic elements, which can accelerate the diffusion of oxygen atoms in the surface structure of the steel plate, promote the reaction of carbon and oxygen atoms in the surface structure of the steel plate, and thus form a thicker carbon-poor layer in the surface layer of the wear-resistant steel, which can increase the energy during the transformation of austenite to ferrite during quenching cooling and promote the ferrite phase transition; Cr can improve the tempering stability of the steel, and can avoid the recrystallization of ferrite in the surface layer during the tempering process of heat treatment, thereby reducing the oxidation loss of the surface of the wear-resistant steel; Mo and W can inhibit the diffusion of carbon in the steel plate during heating and reduce the thickness of the surface carbon-poor layer, which is not conducive to the formation of ferrite structure in the surface layer of the wear-resistant steel, and when the content of Mo and W is too high, the high hardenability can accelerate the transformation of austenite to martensite, thereby reducing the thickness of the ferrite layer.

[0073] Therefore, in the present application, for the wear-resistant steel plate to obtain a ferrite surface layer with a thickness of 50 microns or more, the mass percentage of the chemical elements in the high cold-bending wear-resistant steel plate satisfies: Thus, the high cold-bending wear-resistant steel plate can be 90° cold-bent, and D=(2-4)a is satisfied.

[0074] Further, the high cold-bending wear-resistant steel plate also contains, in mass percentage: Cu≤0.40%, Ni≤0.6%. Specifically, in the present application, the design principles of Cu and Ni in the high cold-bending wear-resistant steel plate are as follows:

[0075] Cu: Cu can improve the quenchability and hardenability, and also has the effect of strengthening ferrite. However, too high Cu content will cause thermal embrittlement of the steel.

[0076] Therefore, in the present application, for the high cold-bending wear-resistant steel plate to be 90° cold-bent and satisfy D=(2-4)a, Cu can be added to improve the hardenability and strengthen the ferrite, and preferably, the mass percentage of Cu in the wear-resistant steel is ≤0.40%.

[0077] Ni: Ni has the effect of refining the tempered martensite structure and inhibiting the diffusion of carbon elements, which can improve the toughness of the steel. However, too high Ni content will increase the carbon equivalent and deteriorate the welding performance, and Ni is a noble metal which will increase the cost.

[0078] Therefore, in the present application, for the high cold-bending wear-resistant steel plate to be 90° cold-bent and satisfy D=(2-4)a, Ni can be added to improve the toughness of the steel, and preferably, the mass percentage of Ni in the high cold-bending wear-resistant steel plate is ≤0.6%.

[0079] Further, the high cold-bending wear-resistant steel plate has an impact energy at -60 ℃ of >80 J, a Vickers hardness of the surface layer of <200 HV, and a Vickers hardness of the core of 400-550 HV. That is, the low-temperature impact toughness of the high cold-bending wear-resistant steel plate can be improved by the above-mentioned component design of the high cold-bending wear-resistant steel plate; the cold-bending performance of the high cold-bending wear-resistant steel plate is further improved by the Vickers hardness of the surface layer of <200 HV; and the wear resistance of the high cold-bending wear-resistant steel plate can be ensured by the Vickers hardness of the core of 400-550 HV.

[0080] The application further provides a manufacturing method of the high cold-bending wear-resistant steel plate, comprising the following steps: S1, proportioning according to chemical element composition, and then refining and casting to obtain a casting blank; S2, hot-rolling the casting blank in step S1 to obtain a hot-rolled steel plate, and step S2 comprises: S21, heating the casting blank to 1200-1260 ℃ in a heating furnace and keeping the temperature for 1-3 h; S22, rolling the casting blank in step S21 by more than one pass to obtain the hot-rolled steel plate, and the finish rolling temperature is 820-900 ℃ in the rolling step; S23, cooling the hot-rolled steel plate in step S22; S3, heat-treating the hot-rolled steel plate obtained in step S2 to obtain the high cold-bending wear-resistant steel plate. That is, on the basis of the above-mentioned component design, the cold-bending performance and the low-temperature impact toughness of the high cold-bending wear-resistant steel plate are further improved by the optimized manufacturing process. For the high cold-bending wear-resistant steel plate of the embodiment of the application, the finish rolling temperature during hot-rolling is controlled to be 820-900 ℃, which can promote more bainite to form on the surface of the hot-rolled steel plate, so that more ferrite is formed on the surface layer of the high cold-bending wear-resistant steel plate after heat-treatment.

[0081] Further, step S23 comprises: S231, cooling the hot-rolled steel plate in step S22 to 500-600 ℃ at a cooling speed of >20 ℃ / s; and S232, continuing to air cool the hot-rolled steel plate cooled to 500-600 ℃ in step S231 to room temperature. That is, the hot-rolled steel plate is first rapidly cooled from 820-900 ℃ to 500-600 ℃ at a cooling speed of >20 ℃ / s, and then the hot-rolled steel plate is placed in air to be air cooled to room temperature, so that more bainite can be further promoted to form on the surface of the hot-rolled steel plate, and more ferrite is finally formed on the surface layer of the high cold-bending wear-resistant steel plate.

[0082] It is worth noting that after the hot-rolled steel plate is rapidly cooled to 500-600 ℃, the hot-rolled steel plate can also be coiled at this temperature, and then air cooled to room temperature after the coiling is completed. This cooling method can avoid the reheating of the hot-rolled steel plate cooled to room temperature, and can save manufacturing cost and improve production efficiency.

[0083] Further, the step S3 comprises: S31, under a protective gas atmosphere, placing the hot-rolled steel plate in step S2 into a quenching furnace for quenching treatment, the quenching temperature being 880-950°C, and after holding for 8-20 min, rapidly cooling to room temperature at a cooling rate of 50-200°C / s; S32, carrying out tempering treatment on the hot-rolled steel plate in step S31, the tempering temperature being 180-250°C, and after holding for 10-40 min, air cooling to room temperature. That is to say, under a protective atmosphere, by controlling the quenching temperature, holding time, cooling rate in the quenching step, and the tempering temperature, tempering time, a high cold-bending wear-resistant steel plate with good cold-bending performance and low-temperature impact toughness can be obtained.

[0084] Specifically, the quenching temperature of 880-950°C is conducive to austenitizing, and the calculation method of the quenching temperature can be set as Ac3+(10-80)°C, wherein the calculation formula of Ac3may be, for example, Ac3=955-350C-25Mn+51Si+106Nb+100Ti+68Al-11Cr-33Ni-16Cu+67Mo, wherein C, Mn, Si, Nb, Ti, Al, Cr, Ni, Cu, and Mo each respectively represent the mass percentage of each in the high cold-bending wear-resistant steel plate.

[0085] The protective atmosphere may, for example, use nitrogen or other inert gases, which are not specifically limited here. The protective atmosphere is used to control the oxygen content in the quenching furnace, so that the oxygen in the atmosphere diffuses from the surface of the high cold-bending wear-resistant steel plate to the inside in the form of oxygen atoms, and especially can quickly diffuse along the grain boundaries. At this time, the oxygen atoms react with the carbon atoms in the high cold-bending wear-resistant steel plate: C+O=CO, and the generated CO will counter-diffuse to the surface layer of the high cold-bending wear-resistant steel plate and react with oxygen again to form carbon dioxide, thereby forming a carbon-poor layer on the surface layer of the high cold-bending wear-resistant steel plate, and the carbon in the transition layer of the high cold-bending wear-resistant steel plate will further diffuse to the surface layer, forming a gradient of increasing carbon content from the surface to the inside in the high cold-bending wear-resistant steel plate.

[0086] The quenching holding time of 8-20 min can ensure that a carbon-poor layer with a thickness of 150 microns or more is formed on the surface layer of the high cold-bending wear-resistant steel plate.

[0087] The cooling rate of the quenching of 50-200°C / s can ensure that the carbon-poor layer on the surface layer of the high cold-bending wear-resistant steel plate forms ferrite, the mixed structure of ferrite and martensite is formed in the transition layer of the high cold-bending wear-resistant steel plate, and the martensite structure is formed in the core of the high cold-bending wear-resistant steel plate. When the cooling rate is lower, the core of the high cold-bending wear-resistant steel plate does not obtain the martensite structure; when the cooling rate is too high, part of the carbon-poor layer on the surface layer of the high cold-bending wear-resistant steel plate will also form the martensite structure, resulting in less ferrite structure on the surface layer, which is limited for improving the cold-bending performance.

[0088] Further, the tempering temperature is 180-250℃ and the tempering holding time is 10-40min, so that the martensite structure of the transition layer and the core of the high cold-bending wear-resistant steel plate is transformed into tempered martensite structure, and the plasticity and toughness of the high cold-bending wear-resistant steel plate are further improved.

[0089] Further, in step S31, the oxygen content of the quenching furnace is 50-300ppm. That is, when the oxygen content of the quenching furnace is 50-300ppm, the diffusion of oxygen atoms is more favorable, so that the thickness of the carbon-poor layer of the surface layer of the high cold-bending wear-resistant steel plate is further increased, and finally the ferrite surface layer with a thickness greater than 50 microns is formed.

[0090] In order to make the purpose, technical scheme and advantages of the present application more clear, the embodiments of the present application will be further described in detail below.

[0091] Examples 1-10 and Comparative Examples 1-2

[0092] The high cold-bending wear-resistant steel plate of Examples 1-10 of the present application is prepared by the following steps:

[0093] (1) The chemical elements are proportioned according to Table 1, and then refined and cast to obtain a cast blank;

[0094] (2) The cast blank is hot-rolled to obtain a hot-rolled steel plate. The heating temperature, heating holding time and final rolling temperature in the hot-rolling step are shown in Table 2, and the cooling speed and cooling midpoint temperature in the cooling step after rolling are shown in Table 2;

[0095] (3) The hot-rolled steel plate is heat-treated. The quenching treatment and tempering treatment in the heat treatment are carried out according to Table 3.

[0096] The steel plate of Comparative Examples 1-2 is proportioned according to the components and component contents shown in Table 1, and manufactured according to the process parameters of Tables 2-3.

[0097] Specifically, Table 1 lists the components and ferrite stabilizing element FEE values of the high cold-bending wear-resistant steel plate of Examples 1-10 and the steel plate of Comparative Examples 1-2, wherein the FEE can be calculated according to the formula .

[0098] Table 1 Components (wt.%) and FEE values of the high cold-bending wear-resistant steel plate of Examples 1-10 and the steel plate of Comparative Examples 1-2

[0099]

[0100] Table 2 lists the main process parameters of the hot-rolling step and the main process parameters in the cooling step after hot-rolling of Examples 1-10 and Comparative Examples 1-2.

[0101] Table 2 Main process parameters of the hot rolling step and main process parameters in the cooling step after hot rolling of Examples 1-10 and Comparative Examples 1-2

[0102]

[0103] Table 3 lists the main process parameters of the heat treatment step of Examples 1-10 and Comparative Examples 1-2.

[0104] Table 3 Main process parameters of the heat treatment step of Examples 1-10 and Comparative Examples 1-2

[0105]

[0106] The high cold-bending wear-resistant steel plate according to the embodiments of the present application, Figure 1 The metallographic diagram of the high cold-bending wear-resistant steel plate according to Embodiment 3 of the present application is shown, it can be seen that the surface layer of the high cold-bending wear-resistant steel plate has a layer of ferrite structure with an average thickness of 58 microns, and the average diameter of the ferrite is 35 microns; the transition layer has a layer of ferrite + tempered martensite structure with an average thickness of 80 microns, and the average diameter of the ferrite is 6 microns; the core of the high cold-bending wear-resistant steel plate is a tempered martensite structure, and the average diameter of the original austenite corresponding to the tempered martensite is 15 microns. Figure 2 The metallographic diagram of the steel plate according to Comparative Example 1 of the present application is shown, it can be seen that the surface layer and the core of Comparative Example 1 both form a martensite structure; Figure 3 The metallographic diagram of the steel plate according to Comparative Example 3 of the present application is shown, it can be seen that the surface layer and the core of Comparative Example 3 both form a martensite structure.

[0107] Next, the cold-bending performance and low-temperature impact toughness of the high cold-bending wear-resistant steel plate according to the embodiments of the present application are further verified through performance tests.

[0108] The high cold-bending wear-resistant steel plates according to Examples 1-10 and the steel plates according to Comparative Examples 1-2 are sampled respectively, and the cold-bending performance, Vickers hardness and low-temperature impact toughness of the high cold-bending wear-resistant steel plates according to Examples 1-10 and the steel plates according to Comparative Examples 1-2 are tested respectively. Table 4 lists the test results of Examples 1-10 and Comparative Examples 1-2.

[0109] Table 4 Test results of Examples 1-10 and Comparative Examples 1-2

[0110]

[0111] Note: I, II, III in Table 4 respectively represent the test results of three parallel samples corresponding to Examples 1-10 and Comparative Examples 1-2.

[0112] As can be seen from Tables 1-4, since each high cold-bending wear-resistant steel plate in Examples 1-10 has the mass percentage of chemical elements defined in the present application and is processed according to the manufacturing method provided in the present application, the high cold-bending wear-resistant steel plate of the present application has good cold-bending performance and low-temperature impact toughness and also has good wear resistance.

[0113] Specifically, the surface layer with a thickness of 50 microns or more and the transition layer with a thickness of 50 microns or more can be obtained, and the Vickers hardness of the surface layer is < 200 HV. That is, the surface layer forms a soft phase of ferrite, which has good cold-bending performance and low-temperature impact toughness. The Vickers hardness of the core is 400-550 HV, which can ensure the wear resistance of the high cold-bending wear-resistant steel plate. The high cold-bending wear-resistant steel plate 90° cold-bending, d = 3a is qualified. That is, the thickness of the high cold-bending wear-resistant steel plate is a, the bending diameter when 90° bending is D, and D = 3a is satisfied. The high cold-bending wear-resistant steel plate -60℃ impact energy > 80 J.

[0114] In comparison, since the mass percentage of some chemical elements in the steel plate in Comparative Example 1-2 has exceeded the range defined in the technical solution of the present application, and the processing process is not processed according to the manufacturing method provided in the present application, the cold-bending performance and low-temperature impact toughness of the steel plate in Comparative Example 1-2 are poor. Specifically, as shown in Tables 1-4, the mass percentages of Al, Cr, Mo, and ferrite stabilizing element FEE in Comparative Example 1-2 are not within the range defined in the technical solution of the present application, and the holding time of the quenching treatment in the cooling step after hot rolling and the furnace oxygen content in the heat treatment of the manufacturing method are not according to the manufacturing method provided in the present application, thereby affecting the cold-bending performance and low-temperature impact toughness of the steel plate in Comparative Example 1-2.

[0115] The above describes the preferred embodiments of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A high-temperature cold-bending wear-resistant steel plate, characterized in that, From the surface inwards, the components are as follows: The surface layer has a metallographic structure of ferrite and a thickness of 50 micrometers or more. A transition layer, located below the surface layer, wherein the metallographic structure of the transition layer is a mixture of ferrite and tempered martensite, and the thickness of the transition layer is 50 micrometers or more; The core portion, wherein the metallographic structure of the core portion is tempered martensite; The total thickness of the high cold-bending wear-resistant steel plate is 4mm or more; With the thickness of the high cold-bending wear-resistant steel plate as a, the bending diameter when bending at 90° is D, satisfying D=na, where n is 2-4; The high cold-bending wear-resistant steel plate comprises an iron-based matrix and chemical elements dispersed in the iron-based matrix in the following mass percentages: C: 0.190%~0.250%, Mn: 0.60%~2.0%, Si: 0.05%~1.0%, Al: 0.030%~0.080%, Cr: 0.20%~0.80%, B: 0.00050%~0.0030%, P≤0.020%, S≤0.0050%, Mo≤0.30%, W≤0.30%, and microalloying elements≤0.20%, wherein the microalloying elements include any one or more of Nb, Ti, and V; The high cold bending wear-resistant steel plate has an impact energy of >80J at -60℃, the Vickers hardness of the surface layer is <200HV, and the Vickers hardness of the core is 400~550HV.

2. The high cold-bending wear-resistant steel plate according to claim 1, characterized in that, The microalloying elements include: Nb: 0.010%–0.040%, Ti: 0.010%–0.050%, and V: 0.010%–0.03%.

3. The high cold-bending wear-resistant steel plate according to claim 1, characterized in that, The mass percentage of chemical elements in the high-temperature cold-bending wear-resistant steel plate satisfies: 10.2* +3.5*Cr-5.2*Mo-4.6*W>2.

5.

4. The high cold-bending wear-resistant steel plate according to claim 1, characterized in that, The high cold bending wear-resistant steel plate also contains, by mass percentage: Cu≤0.40%, Ni≤0.6%.

5. A method for manufacturing a high-temperature cold-bending wear-resistant steel plate, applied to the high-temperature cold-bending wear-resistant steel plate according to any one of claims 1-4, characterized in that, Includes the following steps: S1 is formulated according to the chemical element composition, then refined and cast to obtain a billet; S2, hot rolling the billet from step S1 to obtain a hot-rolled steel plate, step S2 includes: S21, the billet is placed in a heating furnace and heated to 1200~1260℃, and held at that temperature for 1~3 hours; S22, the billet in step S21 is rolled in one or more passes to obtain the hot-rolled steel plate, wherein the final rolling temperature in the hot rolling step is 820~900℃. S23, Cool the hot-rolled steel plate from step S22; S3, the hot-rolled steel plate obtained in step S2 is subjected to heat treatment to obtain the high cold bending wear-resistant steel plate.

6. The method according to claim 5, characterized in that, Step S23 includes: S231, the hot-rolled steel plate in step S22 is cooled to 500~600℃ at a cooling rate of 20℃ / s or higher; S232, the hot-rolled steel plate cooled to 500~600℃ in step S231 is further air-cooled to room temperature.

7. The method according to claim 5, characterized in that, Step S3 includes: S31. Under a protective gas atmosphere, the hot-rolled steel plate from step S2 is placed in a quenching furnace for quenching treatment. The quenching temperature is 880~950℃, and after holding for 8~20 minutes, it is rapidly cooled to room temperature at a cooling rate of 50~200℃ / s. S32, the hot-rolled steel plate from step S31 is tempered at a temperature of 180~250℃, held for 10~40 minutes and then air-cooled to room temperature.

8. The method according to claim 7, characterized in that, In step S31, the oxygen content of the quenching furnace is 50~300ppm.

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