Dual-phase wear-resistant steel and preparation method therefor

Abstract

The present application discloses dual-phase wear-resistant steel and a preparation method therefor. The dual-phase wear-resistant steel has a metallographic microstructure comprising ferrite and martensite. On the basis of a total mass of the dual-phase wear-resistant steel, components of the dual-phase wear-resistant steel comprise: C: 0.18%-0.22%, Si: 0.10%-0.20%, Mn: 1.1%-1.30%, P: ≤ 0.015%, S: ≤ 0.002%, Cr: 0.25%-0.35%, Ti: 0.01%-0.03%, Als: 0.02%-0.06%, Nb: 0.015%-0.025%, and a balance being Fe and unavoidable trace elements. The dual-phase wear-resistant steel has a low yield-to-tensile strength ratio, high tensile strength and high hardness, and superior wear resistance.

Description

Duplex wear-resistant steel and its preparation method Technical Field

[0001] This application belongs to the field of wear-resistant steel technology, and particularly relates to a duplex wear-resistant steel and its preparation method. Background Technology

[0002] Wear-resistant steel is a widely used wear-resistant material in various wear conditions. Low-alloy wear-resistant steel, developed in the 1970s and 80s, is widely used in mining machinery, engineering machinery, wear-resistant liners, agricultural machinery, building materials, power machinery, and railway transportation, such as dump truck bodies, concrete mixer cylinders and blades, and various mechanical equipment liners, baffles, and base plates. Wear-resistant steel plates serve in harsh environments, requiring extremely high strength, hardness, and wear resistance. With the increasing complexity and lightweighting of various mechanical equipment, wear-resistant steel plates, in addition to high strength, high hardness, and high wear resistance, need to possess better processing and forming properties. However, existing wear-resistant steels suffer from significant differences in longitudinal and transverse properties, high internal stress, and large fluctuations in processing and forming characteristics. Summary of the Invention

[0003] This application provides a duplex wear-resistant steel and its preparation method. The duplex wear-resistant steel has a low yield strength ratio, high tensile strength and hardness, and excellent wear resistance.

[0004] In a first aspect, a duplex wear-resistant steel is provided, the microstructure of which includes ferrite and martensite, and the composition of the duplex wear-resistant steel, based on the total mass of the duplex wear-resistant steel, comprises:

[0005] C: 0.18%~0.22%, Si: 0.10%~0.20%, Mn: 1.1%~1.30%, P: ≤0.015%, S: ≤0.002%, Cr: 0.25%~0.35%, Ti: 0.01%~0.03%, Als: 0.02%~0.06%, Nb: 0.015%~0.025%, and the balance being Fe and unavoidable trace elements.

[0006] The duplex wear-resistant steel of this application has small differences in longitudinal and transverse properties, as well as high tensile strength and hardness, and superior wear resistance. At the same time, the duplex wear-resistant steel of this application adopts a low alloy composition design, and the low carbon equivalent gives the duplex wear-resistant steel good weldability. In addition, the addition of less precious alloys reduces the preparation cost of the steel.

[0007] In some specific embodiments, the microstructure of the duplex wear-resistant steel comprises 25 vol% to 35 vol% ferrite and 65 vol% to 75 vol% martensite.

[0008] In the above specific embodiments, the duplex wear-resistant steel of this application improves the processing and forming performance of the duplex wear-resistant steel by controlling the content of ferrite and martensite in the metallographic structure, while also enabling it to obtain higher hardness and strength to improve its wear resistance.

[0009] In some specific embodiments, the duplex wear-resistant steel satisfies at least one of the following: (1) the yield strength of the duplex wear-resistant steel is 600MPa~750MPa; (2) the tensile strength of the duplex wear-resistant steel is 1000MPa~1150MPa; (3) the hardness of the duplex wear-resistant steel is 300HBW~350HBW; (4) the elongation of the duplex wear-resistant steel is 10%~16%; (5) the yield strength ratio of the duplex wear-resistant steel is ≤0.65.

[0010] In a second aspect, a method for preparing duplex wear-resistant steel according to the first aspect includes the following steps: obtaining molten steel after desulfurization, converter smelting, and refining, and continuously casting it to obtain a continuously cast billet; heating the continuously cast billet to obtain a heated continuously cast billet; rough rolling the heated continuously cast billet to obtain a rough-rolled slab; finishing rolling the rough-rolled slab to obtain a finished-rolled steel plate; sequentially coiling and transversely cutting the finished-rolled steel plate to obtain a steel plate to be heat-treated; quenching and low-temperature tempering of the steel plate to be heat-treated to obtain duplex wear-resistant steel, wherein the heating temperature of the quenching treatment is 20℃~30℃ below AC3.

[0011] The preparation method of this application controls the heating temperature of the quenching treatment to be 20℃~30℃ below AC3, so that the steel is quenched in the two-phase region, and the combined tempering and stress relief of the two-phase structure makes the properties of the two-phase wear-resistant steel more uniform and stable.

[0012] In some specific embodiments, in the step of quenching and low-temperature tempering the steel plate to be heat-treated to obtain duplex wear-resistant steel, the heating temperature of the quenching treatment is 760℃~800℃, and the holding time of the quenching treatment is 20min~50min; and / or, the heating temperature of the tempering treatment is 180℃~240℃, and the holding time of the tempering treatment is 20min~40min.

[0013] In the above specific embodiments, the preparation method of this application controls the degree of austenitization during the heating process by controlling the quenching temperature to 760℃~800℃ and the quenching time to 20min~50min, thereby controlling the proportion of martensite, improving tensile strength, and reducing yield strength ratio.

[0014] In some specific embodiments, in the step of obtaining molten steel after desulfurization, converter smelting, and refining and then continuously casting it to obtain a continuously cast billet, the argon station temperature is ≥1520℃; and / or, the refining time in the ladle refining furnace is ≥40min; and / or, the superheat of the tundish is 10℃~25℃; and / or, the continuous casting speed is 0.8m / min~1.2m / min, and the thickness of the continuously cast billet is 230mm~240mm.

[0015] In some specific embodiments, in the step of obtaining a heated continuous casting billet after heat treatment, the heat treatment temperature is 1220℃~1280℃ and the heat treatment time is 170min~230min.

[0016] In some specific embodiments, in the step of rough rolling the heated continuous casting billet to obtain the rough rolled slab, the surface temperature of the rough rolled slab is 1070℃~1140℃.

[0017] In the above specific embodiments, when the surface temperature of the rough-rolled slab is 1070℃~1140℃, the plasticity of the austenitic structure in the steel can be improved.

[0018] In some specific embodiments, in the step of finishing rolling the rough-rolled slab to obtain the finished steel plate, the surface temperature of the finished steel plate is 880℃~950℃.

[0019] In the above specific embodiments, when the surface temperature of the rough-rolled slab is 1070℃~1140℃ and / or the surface temperature of the finish-rolled steel plate is 880℃~950℃, the grains can be further refined, and the strength and toughness of the steel can be improved.

[0020] In some specific embodiments, in the step of sequentially coiling and transversely cutting the finished steel plate to obtain the steel plate to be heat-treated, the coiling temperature is 580℃~650℃.

[0021] In the above specific embodiments, when the winding temperature is 580℃~650℃, the oxide on the surface of the steel is more dense and is not easy to fall off during the steel coil opening and leveling process, reducing the surface pressing caused by the straightening process. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 is a metallographic diagram of the duplex wear-resistant steel in one embodiment of this application.

[0024] Figure 2 is a metallographic diagram of the duplex wear-resistant steel in another embodiment of this application. Detailed Implementation

[0025] To make the inventive objectives, technical solutions, and beneficial technical effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the embodiments described in this specification are merely illustrative and not intended to limit the scope of this application.

[0026] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an unspecified range.

[0027] In the description herein, when a composition is described as containing, comprising, or including a specific component, or when a process is described as containing, comprising, or including a specific process step, it is anticipated that the composition of this application is also primarily composed of or consisting of the said component, and that the process of this application is also primarily composed of or consisting of the said process step.

[0028] Unless otherwise expressly stated, the use of the terms “including,” “contains,” “comprising,” “containing,” and “having” should generally be interpreted as open-ended and non-restrictive.

[0029] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, and "multiple" in "one or more" means two or more.

[0030] The foregoing description of this invention is not intended to describe every disclosed embodiment or implementation. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are merely representative and should not be construed as exhaustive.

[0031] Wear-resistant steel is a widely used wear-resistant material in various wear conditions. Low-alloy wear-resistant steel, developed in the 1970s and 80s, is widely used in mining machinery, engineering machinery, wear-resistant liners, agricultural machinery, building materials, power machinery, and railway transportation, such as dump truck bodies, concrete mixer cylinders and blades, and various mechanical equipment liners, baffles, and base plates. Wear-resistant steel plates serve in harsh environments, requiring extremely high strength, hardness, and wear resistance. With the increasing complexity and lightweighting of various mechanical equipment, wear-resistant steel plates, in addition to high strength, high hardness, and high wear resistance, need to possess better processing and forming properties. However, existing wear-resistant steels use a post-rolling online quenching process, resulting in significant differences in longitudinal and transverse properties, high internal stress, and large fluctuations in processing and forming.

[0032] Based on the above problems, this application provides a dual-phase wear-resistant steel and its preparation method. The dual-phase wear-resistant steel has a low yield strength ratio, high tensile strength and hardness, and excellent wear resistance.

[0033] The duplex wear-resistant steel of this application will be introduced below.

[0034] Duplex wear-resistant steel

[0035] A duplex wear-resistant steel, the microstructure of which includes ferrite and martensite, comprises, based on the total mass of the duplex wear-resistant steel, the composition of which includes: C: 0.18%~0.22%, Si: 0.10%~0.20%, Mn: 1.1%~1.30%, P: ≤0.015%, S: ≤0.002%, Cr: 0.25%~0.35%, Ti: 0.01%~0.03%, Als: 0.02%~0.06%, Nb: 0.015%~0.025%, and the balance being Fe and unavoidable trace elements.

[0036] The duplex wear-resistant steel of this application has small differences in longitudinal and transverse properties, as well as high tensile strength and hardness, and superior wear resistance. At the same time, the duplex wear-resistant steel of this application adopts a low alloy composition design, and the low carbon equivalent gives the duplex wear-resistant steel good weldability. In addition, the addition of less precious alloys reduces the preparation cost of the steel.

[0037] In some specific embodiments, as shown in Figures 1 and 2, the microstructure of the duplex wear-resistant steel comprises 25 vol% to 35 vol% ferrite and 65 vol% to 75 vol% martensite.

[0038] As an example, the metallographic structure of the biaxial wear-resistant steel in this application may include 25 vol% ferrite and the balance of martensite, 28 vol% ferrite and the balance of martensite, 30 vol% ferrite and the balance of martensite, 32 vol% ferrite and the balance of martensite, 35 vol% ferrite and the balance of martensite, or a range consisting of any two of these values.

[0039] In the above specific embodiments, the duplex wear-resistant steel of this application improves the processing and forming performance of the duplex wear-resistant steel by controlling the content of ferrite and martensite in the metallographic structure, while also enabling it to obtain higher hardness and strength to improve its wear resistance.

[0040] In some specific embodiments, the duplex wear-resistant steel satisfies at least one of the following: (1) the yield strength of the duplex wear-resistant steel is 600MPa~750MPa, for example, the yield strength of the duplex wear-resistant steel can be 600MPa, 620MPa, 650MPa, 680MPa, 700MPa, 720MPa, 750MPa or any two of these values; (2) the tensile strength of the duplex wear-resistant steel is 1000MPa~1150MPa, for example, the tensile strength of the duplex wear-resistant steel can be 1000MPa, 1020MPa, 1050MPa, 1080MPa, 1100MPa, 1120MPa, 1150MPa or any two of these values. (3) The hardness of duplex wear-resistant steel is 300HBW~350HBW. For example, the hardness of duplex wear-resistant steel can be 300HBW, 310HBW, 320HBW, 330HBW, 340HBW, 350HBW or any two of these values; (4) The elongation of duplex wear-resistant steel is 10%~16%. For example, the elongation of duplex wear-resistant steel can be 10%, 11%, 12%, 13%, 14%, 15% or any two of these values; (5) The yield strength ratio of duplex wear-resistant steel is ≤0.65. For example, the yield strength ratio of duplex wear-resistant steel can be 0.65, 0.60, 0.58, 0.55, 0.52, 0.50 or any two of these values.

[0041] Preparation method of duplex wear-resistant steel

[0042] A method for preparing the above-mentioned duplex wear-resistant steel includes the following steps: obtaining molten steel after desulfurization, converter smelting, and refining, and continuously casting it to obtain a continuously cast billet; heating the continuously cast billet to obtain a heated continuously cast billet; rough rolling the heated continuously cast billet to obtain a rough-rolled slab; finishing rolling the rough-rolled slab to obtain a finished-rolled steel plate; sequentially coiling and transversely cutting the finished-rolled steel plate to obtain a steel plate to be heat-treated; quenching and low-temperature tempering of the steel plate to be heat-treated to obtain duplex wear-resistant steel, wherein the heating temperature of the quenching treatment is 20℃~30℃ below AC3.

[0043] It should be noted that AC3 temperature refers to the final temperature at which all ferrite is transformed into austenite when hypoeutectoid steel is heated.

[0044] As an example, the heating temperature for quenching is 20°C, 22°C, 25°C, 28°C, or 30°C below AC3, or a range of any two of these values.

[0045] The preparation method of this application controls the heating temperature of the quenching treatment to be 20℃~30℃ below AC3, so that the steel is quenched in the two-phase region, and the combined tempering and stress relief of the two-phase structure makes the properties of the two-phase wear-resistant steel more uniform and stable.

[0046] In some specific embodiments, in the step of quenching and low-temperature tempering the steel plate to be heat-treated to obtain duplex wear-resistant steel, the quenching temperature is 760℃~800℃, for example, the quenching temperature can be 760℃, 770℃, 780℃, 790℃, 800℃ or any two of these values, and the quenching holding time is 20min~50min, for example, the quenching holding time can be 20min, 25min, 30min, 35min, 40min, 45min, etc. 50 min or a range of any two of these values; and / or, the heating temperature for tempering is 180℃~240℃, for example, the heating temperature for tempering can be 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃ or a range of any two of these values, and the holding time for tempering is 20 min~40 min, for example, the holding time for quenching can be 20 min, 25 min, 30 min, 35 min, 40 min or a range of any two of these values.

[0047] In the above specific embodiments, the preparation method of this application controls the degree of austenitization during the heating process by controlling the quenching temperature to 760℃~800℃ and the quenching time to 20min~50min, thereby controlling the proportion of martensite, improving tensile strength, and reducing yield strength ratio.

[0048] In some specific embodiments, in the step of obtaining continuously cast billets from molten steel after desulfurization, converter smelting, and refining, the argon station temperature is ≥1520℃; and / or, the refining time in the ladle refining furnace is ≥40min; and / or, the tundish superheat is 10℃~25℃, for example, the tundish superheat can be 10℃, 12℃, 15℃, 18℃, 20℃, 22℃, 25℃ or any two of these values; and / or, the continuous casting speed is 0.8m / min~1.2m / min, for example, the continuous casting speed can be 0.8m / min, 0.85m / min, 0.9m / min, 0.95m / min, 1m / min, 1.05m / min, 1.1m / min, 1.15m / min, 1.2m / min or any two of these values, and the thickness of the continuously cast billet is 230mm~240mm.

[0049] It should be noted that the desulfurization of molten iron can be carried out using the KR method, and the refining can be carried out using a ladle refining furnace (LF refining).

[0050] In some specific embodiments, in the step of obtaining a heated continuous casting billet after heat treatment, the heat treatment temperature is 1220℃~1280℃. For example, the heat treatment temperature can be 1220℃, 1230℃, 1240℃, 1250℃, 1260℃, 1270℃, 1280℃, or any two of these values. The heat treatment time is 170min~230min. For example, the heat treatment time can be 170min, 180min, 190min, 200min, 210min, 220min, 230min, or any two of these values.

[0051] In some specific embodiments, in the step of rough rolling the heated continuously cast billet to obtain the rough-rolled slab, the surface temperature of the rough-rolled slab is 1070℃~1140℃. For example, the surface temperature of the rough-rolled slab can be 1070℃, 1080℃, 1090℃, 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, or a range of any two of these values.

[0052] In the above specific embodiments, when the surface temperature of the rough-rolled slab is 1070℃~1140℃, the plasticity of the austenitic structure in the steel can be improved.

[0053] In some specific embodiments, in the step of finishing rolling the rough-rolled slab to obtain the finished-rolled steel plate, the surface temperature of the finished-rolled steel plate is 880℃~950℃. For example, the surface temperature of the finished-rolled steel plate can be 880℃, 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, or a range of any two of these values.

[0054] In the above specific embodiments, when the surface temperature of the rough-rolled slab is 1070℃~1140℃ and / or the surface temperature of the finish-rolled steel plate is 880℃~950℃, the grains can be further refined, and the strength and toughness of the steel can be improved.

[0055] In some specific embodiments, in the step of sequentially coiling and cross-cutting the finished steel sheet to obtain the steel sheet to be heat-treated, the coiling temperature is 580℃~650℃. For example, the coiling temperature can be 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, or a range of any two of these values.

[0056] In the above specific embodiments, when the winding temperature is 580℃~650℃, the oxide on the steel surface is more dense and is less likely to fall off during the steel coil opening and leveling process, reducing surface pressing caused by the straightening process.

[0057] Example

[0058] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0059] Example 1

[0060] A duplex wear-resistant steel, based on its total mass, comprises the following components: C: 0.201%, Si: 0.153%, Mn: 1.18%, P: 0.007%, S: 0.0015%, Cr: 0.286%, Ti: 0.026%, Als: 0.048%, Nb: 0.021%, and the balance being Fe and other unavoidable trace elements. The microstructure of the duplex wear-resistant steel comprises 29 vol% ferrite and 70 vol% martensite.

[0061] The above-mentioned duplex wear-resistant steel is prepared by the following steps:

[0062] Molten iron is successively desulfurized by the KR method, steelmaking in a converter, refining in an LF furnace, and cast into a continuous casting billet. The continuous casting billet has a thickness of 230 mm and a width of 1600 mm. The temperature of the converter argon station is 1525℃, the refining time of the molten steel in the LF furnace is 45 min, the superheating degree of the tundish is 13℃, and the casting speed of the continuous casting billet is 1.1 m / min.

[0063] After being slowly cooled in the finished product warehouse for 12 hours, the continuously cast billet is loaded into the furnace for heating treatment. The temperature of the soaking zone of the heating furnace is set at 1240℃, and the total time of the steel plate in the furnace is 200 minutes, resulting in the heated slab.

[0064] The heated slab was subjected to 7 passes of rough rolling to obtain the rough-rolled slab. The surface temperature of the rough-rolled slab was measured to be 1133℃.

[0065] The rough-rolled slab is then finished-rolled to obtain a finished steel plate. The surface temperature of the finished steel plate is 910℃.

[0066] The finished steel sheet is cooled using a layer cooling process, then coiled at an average temperature of 610℃. The coils are then sent to the finished product warehouse for packaging and printing, and slowly cooled to room temperature in a slow cooling box. The hot-rolled steel coils have a specification of 4.0mm × 1600mm. The coiled steel coils are then cross-cut to obtain the steel sheet to be heat-treated.

[0067] The steel plate to be heat-treated was subjected to quenching and tempering. The quenching temperature was 780℃ and the holding time was 40min. The tempering temperature was 220℃ and the holding time was 25min. After tempering, it was slowly cooled on a cooling bed to obtain duplex wear-resistant steel.

[0068] Example 2

[0069] A duplex wear-resistant steel, based on its total mass, comprises the following components: C: 0.205%, Si: 0.163%, Mn: 1.21%, P: 0.008%, S: 0.0014%, Cr: 0.266%, Ti: 0.024%, Als: 0.039%, Nb: 0.019%, and the balance being Fe and other unavoidable trace elements. The microstructure of the duplex wear-resistant steel comprises 27 vol% ferrite and 72 vol% martensite.

[0070] The above-mentioned duplex wear-resistant steel is prepared by the following steps:

[0071] Molten iron is successively desulfurized by the KR method, steelmaking in a converter, refining in an LF furnace, and cast into a continuous casting billet. The continuous casting billet has a thickness of 230 mm and a width of 1600 mm. The temperature of the converter argon station is 1524℃, the refining time of the molten steel in the LF furnace is 43 min, the superheating degree of the tundish is 12℃, and the casting speed of the continuous casting billet is 1.05 m / min.

[0072] After being slowly cooled in the finished product warehouse for 12 hours, the continuously cast billet was loaded into the furnace for heating treatment. The temperature of the soaking zone of the heating furnace was set at 1235℃, and the total time of the steel plate in the furnace was 202 minutes, resulting in the heated slab.

[0073] The heated slab was subjected to 7 passes of rough rolling to obtain the rough-rolled slab. The surface temperature of the rough-rolled slab was measured to be 1136℃.

[0074] The rough-rolled slab is then finished-rolled to obtain a finished steel plate. The surface temperature of the finished steel plate is 912℃.

[0075] The finished steel sheet is cooled using a layer cooling process, then coiled at an average coiling temperature of 607℃. The coils are then sent to the finished product warehouse for packaging and printing, and slowly cooled to room temperature in a slow cooling box. The hot-rolled steel coils have a specification of 4.0mm × 1600mm. The coiled steel coils are then cross-cut to obtain the steel sheet to be heat-treated.

[0076] The steel plate to be heat-treated was subjected to quenching and tempering. The quenching temperature was 780℃ and the holding time was 40min. The tempering temperature was 220℃ and the holding time was 25min. After tempering, it was slowly cooled on a cooling bed to obtain duplex wear-resistant steel.

[0077] Example 3

[0078] A duplex wear-resistant steel, based on its total mass, comprises the following components: C: 0.198%, Si: 0.148%, Mn: 1.21%, P: 0.008%, S: 0.0013%, Cr: 0.275%, Ti: 0.024%, Als: 0.035%, Nb: 0.022%, and the balance being Fe and other unavoidable trace elements. The microstructure of the duplex wear-resistant steel comprises 30 vol% ferrite and 69 vol% martensite.

[0079] The above-mentioned duplex wear-resistant steel is prepared by the following steps:

[0080] Molten iron is successively desulfurized by the KR method, steelmaking in a converter, refining in an LF furnace, and cast into a continuous casting billet. The continuous casting billet has a thickness of 230 mm and a width of 1600 mm. The temperature of the converter argon station is 1527℃, the refining time of the molten steel in the LF furnace is 46 min, the superheating degree of the tundish is 14℃, and the casting speed of the continuous casting billet is 1.08 m / min.

[0081] After being slowly cooled in the finished product warehouse for 13 hours, the continuously cast billet was loaded into the furnace for heating treatment. The temperature of the soaking zone of the heating furnace was set at 1238℃, and the total time of the steel plate in the furnace was 195 minutes, resulting in the heated slab.

[0082] The heated slab was subjected to 7 passes of rough rolling to obtain the rough-rolled slab. The surface temperature of the rough-rolled slab was measured to be 1135℃.

[0083] The rough-rolled slab is then finished-rolled to obtain a finished steel plate. The surface temperature of the finished steel plate is 905℃.

[0084] The finished steel sheet is cooled using a layer cooling process, then coiled at an average temperature of 600℃. The coils are then sent to the finished product warehouse for packaging and printing, and slowly cooled to room temperature in a slow cooling box. The hot-rolled steel coils have a specification of 4.0mm × 1600mm. The coiled steel coils are then cross-cut to obtain the steel sheet to be heat-treated.

[0085] The steel plate to be heat-treated was subjected to quenching and tempering. The quenching temperature was 780℃ and the holding time was 40min. The tempering temperature was 220℃ and the holding time was 25min. After tempering, it was slowly cooled on a cooling bed to obtain duplex wear-resistant steel.

[0086] Comparative Example 1

[0087] The only difference between this comparative example and Example 1 is that the quenching temperature during the preparation process is 700°C. The other raw materials and preparation process are the same as in Example 1. The metallographic structure of this steel is mainly ferrite + pearlite.

[0088] Comparative Example 2

[0089] The only difference between this comparative example and Example 1 is that the quenching temperature during the preparation process is 880°C. The other raw materials and preparation process are the same as in Example 1. The metallographic structure of this steel is tempered martensite.

[0090] Comparative Example 3

[0091] The only difference between this comparative example and Example 1 is that the tempering temperature during the preparation process is 600°C. The other raw materials and preparation process are the same as in Example 1. The metallographic structure of this steel is ferrite + tempered sorbite.

[0092] Test section

[0093] The samples prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, tensile tests, and hardness tests. The tensile tests were conducted according to the standard GB / T 228.1-2010, and the hardness tests were conducted according to the method of GB / T 231.1-2009. The results are shown in Table 1.

[0094] Table 1. Performance of Samples from Examples 1-3 and Comparative Examples 1-3

[0095]

[0096] As shown in Table 1, the wear-resistant steel plates in Examples 1-3 have a yield strength ratio of approximately 0.58, an elongation of ≥11%, and a surface Brinell hardness of approximately 325 HBW. In Comparative Example 1, the quenching temperature was lowered, resulting in a decrease in the degree of austenitization during the heating process, which led to a decrease in the proportion of martensite after quenching and a rapid decrease in tensile strength. In Comparative Example 2, the quenching temperature was increased to 840℃, which increased the proportion of martensite and decreased the proportion of ferrite after quenching, resulting in an increase in tensile strength and yield strength ratio. In Comparative Example 3, the tempering temperature was increased to 600℃, and no martensite was found in the microstructure, resulting in a significant decrease in strength and hardness.

[0097] The duplex wear-resistant steel of this application has fewer precious alloys added, resulting in lower production costs. Its lower yield strength ensures good processing and forming performance, while its higher tensile strength ensures the wear resistance of the material. It is particularly suitable for manufacturing components with relatively complex structures and has good application prospects.

[0098] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A duplex wear-resistant steel, characterized in that, The microstructure of the duplex wear-resistant steel includes ferrite and martensite; based on the total mass of the duplex wear-resistant steel, the composition of the duplex wear-resistant steel includes: C: 0.18%~0.22%, Si: 0.10%~0.20%, Mn: 1.1%~1.30%, P: ≤0.015%, S: ≤0.002%, Cr: 0.25%~0.35%, Ti: 0.01%~0.03%, Als: 0.02%~0.06%, Nb: 0.015%~0.025%, and the balance being Fe and unavoidable trace elements.

2. The duplex wear-resistant steel according to claim 1, characterized in that, The microstructure of the duplex wear-resistant steel comprises 25 vol% to 35 vol% ferrite and 65 vol% to 75 vol% martensite.

3. The duplex wear-resistant steel according to claim 1, characterized in that, The duplex wear-resistant steel satisfies at least one of the following: (1) The yield strength of the duplex wear-resistant steel is 600MPa~750MPa; (2) The tensile strength of the duplex wear-resistant steel is 1000MPa~1150MPa; (3) The hardness of the duplex wear-resistant steel is 300HBW~350HBW; (4) The elongation of the duplex wear-resistant steel is 10%~16%; (5) The yield strength ratio of the duplex wear-resistant steel is ≤0.

65.

4. A method for preparing duplex wear-resistant steel as described in any one of claims 1 to 3, characterized in that, Includes the following steps: The molten steel after desulfurization, converter smelting, and refining is continuously cast to obtain a continuously cast billet; The continuously cast billet is heated to obtain a heated continuously cast billet; The heated continuous casting billet is rough rolled to obtain a rough rolled slab; The rough-rolled slab is then finished-rolled to obtain a finished-rolled steel plate; The precision-rolled steel plate is sequentially coiled and cross-cut to obtain a steel plate to be heat-treated. The steel plate to be heat-treated is subjected to quenching and low-temperature tempering to obtain the duplex wear-resistant steel, wherein the heating temperature of the quenching treatment is 20℃~30℃ below AC3.

5. The preparation method according to claim 4, characterized in that, In the step of quenching and low-temperature tempering the steel plate to be heat-treated to obtain the duplex wear-resistant steel, the heating temperature of the quenching treatment is 760℃~800℃, and the holding time of the quenching treatment is 20min~50min. And / or, the heating temperature of the tempering treatment is 180℃~240℃, and the holding time of the tempering treatment is 20min~40min.

6. The preparation method according to claim 4, characterized in that, In the step of continuously casting molten iron after desulfurization pretreatment into continuously cast billets after smelting in a converter and refining in a ladle refining furnace, the temperature of the argon station is ≥1520℃. And / or, the refining time in the ladle refining furnace is ≥40 min; And / or, the superheat of the tundish is 10℃~25℃; And / or, the continuous casting billet pulling speed is 0.8m / min to 1.2m / min, and the thickness of the continuous casting billet is 230mm to 240mm.

7. The preparation method according to claim 4, characterized in that, In the step of obtaining a heated continuous casting billet by heating the billet, the heating temperature is 1220℃~1280℃ and the heating time is 170min~230min.

8. The preparation method according to claim 4, characterized in that, In the step of rough rolling the heated continuous casting billet to obtain a rough rolled slab, the surface temperature of the rough rolled slab is 1070℃~1140℃.

9. The preparation method according to claim 4, characterized in that, In the step of finishing rolling the rough-rolled slab to obtain a finished steel plate, the surface temperature of the finished steel plate is 880℃~950℃.

10. The preparation method according to claim 4, characterized in that, In the step of sequentially coiling and transversely cutting the finished steel plate to obtain the steel plate to be heat-treated, the coiling temperature is 580℃~650℃.

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