Dual-phase wear-resistant steel and preparation method thereof

Abstract

The invention discloses dual-phase wear-resistant steel and a preparation method thereof. The metallographic structure of the double-phase wear-resistant steel comprises ferrite and martensite, and based on the total mass of the double-phase wear-resistant steel, the double-phase wear-resistant steel comprises the following components: 0.18%-0.22% of C, 0.10%-0.20% of Si, 1.1%-1.30% of Mn, less than or equal to 0.015% of P, less than or equal to 0.002% of S, 0.25%-0.35% of Cr, 0.01%-0.03% of Ti, 0.02%-0.06% of Als, 0.015%-0.025% of Nb and the balance of Fe and inevitable trace elements. The double-phase wear-resistant steel has a low yield ratio and also has high tensile strength and hardness, and the wear resistance is more excellent.

Description

Technical Field

[0001] The present application belongs to the technical field of wear-resistant steel, and in particular to a dual-phase wear-resistant steel and a preparation method thereof. Background Art

[0002] Wear-resistant steel is a kind of wear-resistant material widely used in various wear conditions. Among them, low-alloy wear-resistant steel was developed in the 1970s and 1980s and is widely used in mining machinery, engineering machinery, wear-resistant linings, agricultural machinery, building materials, electric power machinery, railway transportation and other departments, such as dump truck compartments, concrete mixer barrels and blades, various mechanical equipment linings, baffles and bottom plates. Wear-resistant steel plates have harsh service environments and require extremely high strength, hardness and wear resistance. With the complexity and lightweight of various types of mechanical equipment, wear-resistant steel plates need to have better processing and forming properties on the basis of high strength, high hardness and high wear resistance. However, existing wear-resistant steels have large differences in longitudinal and transverse performance, large internal stress, and large fluctuations in processing and forming. Summary of the invention

[0003] The embodiment of the present application provides a dual-phase wear-resistant steel and a preparation method thereof. The dual-phase wear-resistant steel has a low yield strength ratio, high tensile strength and hardness, and better wear resistance.

[0004] In a first aspect, a dual-phase wear-resistant steel is provided, the metallographic structure of the dual-phase wear-resistant steel comprising ferrite and martensite, and the components of the dual-phase wear-resistant steel comprising, based on the total mass of the dual-phase wear-resistant steel, 0.18% to 0.22% C, 0.10% to 0.20% Si, 1.1% to 1.30% Mn, ≤0.015% P, ≤0.002% S, 0.25% to 0.35% Cr, 0.01% to 0.03% Ti, 0.02% to 0.06% Als, 0.015% to 0.025% Nb, and the remainder of Fe and unavoidable trace elements.

[0005] The dual-phase wear-resistant steel of the present application has a small difference in longitudinal and transverse performance, and also has higher tensile strength and hardness, and better wear resistance; at the same time, the dual-phase wear-resistant steel of the present application is designed with a low alloy component, and the lower carbon equivalent makes the dual-phase wear-resistant steel have good welding performance, and less precious alloys are added, which reduces the preparation cost of the steel.

[0006] In some specific embodiments, the metallographic structure of the dual-phase wear-resistant steel includes 25 vol% to 35 vol% ferrite and 65 vol% to 75 vol% martensite.

[0007] In the above specific implementation, the dual-phase wear-resistant steel of the present application improves the processing and forming performance of the dual-phase wear-resistant steel by controlling the content of ferrite and martensite in the metallographic structure, while obtaining higher hardness and strength to improve its wear resistance.

[0008] In some specific embodiments, the dual-phase wear-resistant steel satisfies at least one of the following: (1) the yield strength of the dual-phase wear-resistant steel is 600MPa-750MPa; (2) the tensile strength of the dual-phase wear-resistant steel is 1000MPa-1150MPa; (3) the hardness of the dual-phase wear-resistant steel is 300HBW-350HBW; (4) the elongation of the dual-phase wear-resistant steel is 10%-16%; (5) the yield strength ratio of the dual-phase wear-resistant steel is ≤0.65.

[0009] In the second aspect, a preparation method of the dual-phase wear-resistant steel of the first aspect comprises the following steps: obtaining molten steel after desulfurization treatment, converter smelting and refining, and continuously casting to obtain a continuous casting billet; heating the continuous casting billet to obtain a heated continuous casting billet; rough rolling the heated continuous casting billet to obtain a rough-rolled slab; finish rolling the rough-rolled slab to obtain a finish-rolled steel plate; coiling and cross-cutting the finish-rolled steel plate in sequence to obtain a steel plate to be heat-treated; quenching and low-temperature tempering the steel plate to be heat-treated to obtain the dual-phase wear-resistant steel, wherein the heating temperature for the quenching treatment is 20°C to 30°C below AC3.

[0010] The preparation method of the present application controls the heating temperature of the quenching treatment to be 20°C to 30°C below AC3, so that the steel is quenched in the two-phase region, and a two-phase structure is obtained. Combined with tempering to relieve stress, the performance of the two-phase wear-resistant steel is more uniform and stable.

[0011] In some specific embodiments, in the step of quenching and low-temperature tempering the steel plate to be heat treated to obtain dual-phase wear-resistant steel, the heating temperature for the quenching treatment is 760°C to 800°C, and the holding time for the quenching treatment is 20min to 50min; and / or, the heating temperature for the tempering treatment is 180°C to 240°C, and the holding time for the tempering treatment is 20min to 40min.

[0012] In the above specific embodiment, the preparation method of the present application controls the degree of austenitization during the heating process by controlling the quenching temperature to 760°C to 800°C and the quenching time to 20min to 50min, thereby controlling the proportion of martensite, improving the tensile strength, and reducing the yield strength ratio.

[0013] In some specific embodiments, in the step of obtaining molten steel after desulfurization treatment, converter smelting and refining for continuous casting to obtain continuously cast billets, the argon station temperature is ≥1520°C; and / or the refining time in the ladle refining furnace is ≥40min; and / or the superheat of the tundish is 10°C to 25°C; and / or the continuous casting drawing speed is 0.8m / min to 1.2m / min, and the thickness of the continuously cast billet is 230mm to 240mm.

[0014] In some specific embodiments, in the step of heating the continuous casting billet to obtain the heated continuous casting billet, the heating treatment temperature is 1220° C. to 1280° C., and the heating treatment time is 170 min to 230 min.

[0015] In some specific embodiments, 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°C to 1140°C.

[0016] In the above specific implementation, when the surface temperature of the slab after rough rolling is 1070° C. to 1140° C., the plasticity of the austenite structure in the steel can be improved.

[0017] In some specific embodiments, in the step of performing finish rolling on the rough-rolled slab to obtain the finish-rolled steel plate, the surface temperature of the finish-rolled steel plate is 880°C to 950°C.

[0018] In the above specific embodiment, when the surface temperature of the slab after rough rolling is 1070°C to 1140°C and / or the surface temperature of the steel plate after finish rolling is 880°C to 950°C, the grains can be further refined and the strength and toughness of the steel can be improved.

[0019] In some specific embodiments, in the steps of sequentially coiling and cross-cutting the finish-rolled steel plate to obtain the steel plate to be heat-treated, the coiling temperature is 580°C to 650°C.

[0020] In the above specific implementation, when the coiling temperature is 580°C to 650°C, the oxide on the surface of the steel is more compact and is not easy to fall off during the unrolling of the steel coil, thereby reducing the surface pressure caused by the straightening process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1It is a metallographic structure diagram of a dual-phase wear-resistant steel in one embodiment of the present application.

[0023] Figure 2 It is a metallographic structure diagram of a dual-phase wear-resistant steel in another embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to make the invention purpose, technical scheme and beneficial technical effect of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.

[0025] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0026] In the description herein, when a composition is described as containing, comprising or including specific components, or when a process is described as containing, comprising or including specific process steps, it is expected that the composition of the present application also consists essentially of or consists of the components, and the process of the present application also consists essentially of or consists of the process steps.

[0027] The use of the terms "including," "comprising," "containing," and "having" should generally be interpreted as open ended and non-limiting unless expressly stated otherwise.

[0028] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and the “multiple” in “one or more” means more than two.

[0029] The above-mentioned summary of the invention of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example, enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0030] Wear-resistant steel is a kind of wear-resistant material widely used in various wear conditions. Among them, low-alloy wear-resistant steel was developed in the 1970s and 1980s and is widely used in mining machinery, engineering machinery, wear-resistant linings, agricultural machinery, building materials, electric power machinery, railway transportation and other departments, such as dump truck compartments, concrete mixer barrels and blades, various mechanical equipment linings, baffles and bottom plates. Wear-resistant steel plates have harsh service environments and require extremely high strength, hardness and wear resistance. With the complexity and lightweight of various types of mechanical equipment, wear-resistant steel plates need to have better processing and forming properties on the basis of high strength, high hardness and high wear resistance. However, the existing wear-resistant steel adopts the online quenching process after rolling, which makes the longitudinal and transverse performance differences of wear-resistant steel large, the internal stress is large, and the processing and forming fluctuations are large.

[0031] Based on the above problems, the present application provides a dual-phase wear-resistant steel and a preparation method thereof, wherein the dual-phase wear-resistant steel has a low yield strength ratio, high tensile strength and hardness, and better wear resistance.

[0032] The following first introduces the dual-phase wear-resistant steel of the present application.

[0033] Duplex wear resistant steel

[0034] A dual-phase wear-resistant steel, the metallographic structure of the dual-phase wear-resistant steel includes ferrite and martensite, and based on the total mass of the dual-phase wear-resistant steel, the components of the dual-phase wear-resistant steel include: 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 remainder of Fe and inevitable trace elements.

[0035] The dual-phase wear-resistant steel of the present application has a small difference in longitudinal and transverse performance, and also has higher tensile strength and hardness, and better wear resistance; at the same time, the dual-phase wear-resistant steel of the present application is designed with a low alloy component, and the lower carbon equivalent makes the dual-phase wear-resistant steel have good welding performance, and less precious alloys are added, which reduces the preparation cost of the steel.

[0036] In some specific embodiments, Figure 1 and Figure 2 As shown, the metallographic structure of the dual-phase wear-resistant steel includes 25 vol% to 35 vol% ferrite and 65 vol% to 75 vol% martensite.

[0037] As an example, the metallographic structure of the bidirectional wear-resistant steel in the present application may include 25 vol% ferrite and the remainder martensite, 28 vol% ferrite and the remainder martensite, 30 vol% ferrite and the remainder martensite, 32 vol% ferrite and the remainder martensite, 35 vol% ferrite and the remainder martensite, or a range consisting of any two of these values.

[0038] In the above specific embodiments, the dual-phase wear-resistant steel of the present application improves the processing and forming performance of the dual-phase wear-resistant steel by controlling the content of ferrite and martensite in the metallographic structure, while obtaining higher hardness and strength to improve its wear resistance.

[0039] In some specific embodiments, the dual-phase wear-resistant steel satisfies at least one of the following: (1) the yield strength of the dual-phase wear-resistant steel is 600MPa-750MPa, for example, the yield strength of the dual-phase wear-resistant steel can be 600MPa, 620MPa, 650MPa, 680MPa, 700MPa, 720MPa, 750MPa, or a range consisting of any two of the values; (2) the tensile strength of the dual-phase wear-resistant steel is 1000MPa-1150MPa, for example, the tensile strength of the dual-phase wear-resistant steel can be 1000MPa, 1020MPa, 1050MPa, 1080MPa, 1100MPa, 1120MPa, 1150MPa, or a range consisting of any two of the values; (3) The hardness of the dual-phase wear-resistant steel is 300 HBW to 350 HBW, for example, the hardness of the dual-phase wear-resistant steel can be 300 HBW, 310 HBW, 320 HBW, 330 HBW, 340 HBW, 350 HBW or a range consisting of any two values ​​therein; (4) The elongation of the dual-phase wear-resistant steel is 10% to 16%, for example, the elongation of the dual-phase wear-resistant steel can be 10%, 11%, 12%, 13%, 14%, 15% or a range consisting of any two values ​​therein; (5) The yield strength ratio of the dual-phase wear-resistant steel is ≤ 0.65, for example, the yield strength ratio of the dual-phase wear-resistant steel can be 0.65, 0.60, 0.58, 0.55, 0.52, 0.50 or a range consisting of any two values ​​therein.

[0040] Preparation method of dual-phase wear-resistant steel

[0041] A preparation method of the above-mentioned dual-phase wear-resistant steel comprises the following steps: obtaining molten steel after desulfurization treatment, converter smelting and refining, and continuously casting to obtain a continuous casting billet; heating the continuous casting billet to obtain a heated continuous casting billet; rough rolling the heated continuous casting billet to obtain a rough-rolled slab; finish rolling the rough-rolled slab to obtain a finish-rolled steel plate; coiling and cross-cutting the finish-rolled steel plate in sequence to obtain a steel plate to be heat-treated; quenching and low-temperature tempering the steel plate to be heat-treated to obtain the dual-phase wear-resistant steel, wherein the heating temperature of the quenching treatment is 20°C to 30°C below AC3.

[0042] 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.

[0043] As an example, the heating temperature for the quenching treatment is 20° C., 22° C., 25° C., 28° C., 30° C. or a range consisting of any two of the values ​​below AC3.

[0044] The preparation method of the present application controls the heating temperature of the quenching treatment to be 20°C to 30°C below AC3, so that the steel is quenched in the two-phase region, and a two-phase structure is obtained. Combined with tempering to relieve stress, the performance of the two-phase wear-resistant steel is more uniform and stable.

[0045] In some specific embodiments, in the step of performing quenching treatment and low-temperature tempering treatment on the steel plate to be heat treated to obtain the dual-phase wear-resistant steel, the heating temperature of the quenching treatment is 760°C to 800°C, for example, the heating temperature of the quenching treatment can be 760°C, 770°C, 780°C, 790°C, 800°C or a range consisting of any two values ​​therein, and the holding time of the quenching treatment is 20min to 50min, for example, the holding time of the quenching treatment can be 20min, 25min, 30min, 35min, 40min, 45min, 50min or a range consisting of any two of the values ​​therein; and / or, the heating temperature for tempering treatment is 180°C to 240°C, for example, the heating temperature for tempering treatment can be 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or a range consisting of any two of the values ​​therein, and the holding time for tempering treatment is 20min to 40min, for example, the holding time for quenching treatment can be 20min, 25min, 30min, 35min, 40min or a range consisting of any two of the values ​​therein.

[0046] In the above specific embodiments, the preparation method of the present application controls the degree of austenitization during the heating process by controlling the quenching temperature to 760°C to 800°C and the quenching time to 20min to 50min, thereby controlling the proportion of martensite, improving the tensile strength, and reducing the yield strength ratio.

[0047] In some specific embodiments, in the step of obtaining molten steel after desulfurization treatment, converter smelting and refining for continuous casting to obtain continuous casting billets, the argon station temperature is ≥1520°C; and / or the refining time in the ladle refining furnace is ≥40min; and / or the superheat of the tundish is 10°C to 25°C, for example, the superheat of the tundish can be 10°C, 12°C, 15°C, 18°C, 20°C, 22°C, 25°C or a range consisting of any two of the values ​​therein; and / or the speed of continuous casting billet drawing is 0.8m / min to 1.2m / min, for example, the speed of continuous casting billet drawing 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 a range consisting of any two of the values ​​therein, and the thickness of the continuous casting billet is 230mm to 240mm.

[0048] It should be noted that the molten iron desulfurization treatment can adopt the KR method desulfurization, and the refining can adopt the ladle refining furnace refining (LF refining).

[0049] In some specific embodiments, in the step of heating the continuous casting billet to obtain the heated continuous casting billet, the heating treatment temperature is 1220℃~1280℃, for example, the heating treatment temperature can be 1220℃, 1230℃, 1240℃, 1250℃, 1260℃, 1270℃, 1280℃ or a range consisting of any two of the values ​​therein, and the heating treatment time is 170min~230min, for example, the heating treatment time can be 170min, 180min, 190min, 200min, 210min, 220min, 230min or a range consisting of any two of the values ​​therein.

[0050] 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° C. to 1140° C. For example, the surface temperature of the rough rolled slab can be 1070° C., 1080° C., 1090° C., 1100° C., 1110° C., 1120° C., 1130° C., 1140° C., or a range consisting of any two of these values.

[0051] In the above specific embodiment, when the surface temperature of the slab after rough rolling is 1070° C. to 1140° C., the plasticity of the austenite structure in the steel can be improved.

[0052] In some specific embodiments, in the step of performing finish rolling on the rough-rolled slab to obtain the finished steel plate, the surface temperature of the finished steel plate is 880° C. to 950° C. For example, the surface temperature of the finished steel plate can be 880° C., 890° C., 900° C., 910° C., 920° C., 930° C., 940° C., 950° C., or a range consisting of any two of these values.

[0053] In the above specific embodiments, when the surface temperature of the slab after rough rolling is 1070°C to 1140°C and / or the surface temperature of the steel plate after finish rolling is 880°C to 950°C, the grains can be further refined and the strength and toughness of the steel can be improved.

[0054] In some specific embodiments, in the step of sequentially coiling and cross-cutting the finished rolled steel sheet to obtain the steel sheet to be heat treated, the coiling temperature is 580° C. to 650° C. For example, the coiling temperature may be 580° C., 590° C., 600° C., 610° C., 620° C., 630° C., 640° C., 650° C., or a range consisting of any two of these values.

[0055] In the above specific embodiment, when the coiling temperature is 580°C to 650°C, the oxide on the surface of the steel is more compact and is not easy to fall off during the unrolling of the steel coil, thereby reducing the surface pressure caused by the straightening process.

[0056] Example

[0057] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0058] Example 1

[0059] A dual-phase wear-resistant steel, based on the total mass of the dual-phase wear-resistant steel, has 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 remainder of Fe and other inevitable trace elements. The metallographic structure of the dual-phase wear-resistant steel includes 29 vol% ferrite and 70 vol% martensite.

[0060] The above-mentioned dual-phase wear-resistant steel is prepared by the following steps:

[0061] The molten iron is successively subjected to KR desulfurization, converter steelmaking, LF refining and continuous casting to obtain continuous casting billets. The thickness of the continuous casting billet is 230 mm and the width of the continuous casting billet is 1600 mm. Among them, the temperature of the converter argon station is 1525°C, the LF furnace refining time of the molten steel is 45 min, the superheat of the ladle is 13°C, and the continuous casting billet drawing speed is 1.1 m / min.

[0062] The continuous casting slab is slowly cooled in the finished product warehouse for 12 hours and then loaded into the furnace for heating treatment. The setting temperature of the soaking section of the heating furnace is 1240℃, and the total time of the steel plate in the furnace is 200 minutes to obtain the heated slab.

[0063] The heated slab was subjected to 7 passes of rough rolling to obtain a rough rolled slab, and the surface temperature of the rough rolled slab was measured to be 1133°C.

[0064] The rough-rolled slab was subjected to finish rolling to obtain a finish-rolled steel plate, and the surface temperature of the finish-rolled steel plate was 910°C.

[0065] The steel plate after finishing rolling is cooled by layer cooling process and then coiled. The average coiling temperature is 610℃. The steel coil is sent to the finished product warehouse for packaging and then printed. It is slowly cooled to room temperature in the slow cooling box. The hot rolled steel coil specification is 4.0mm×1600mm. The coiled steel coil is then cut horizontally to obtain the steel plate to be heat treated.

[0066] The steel plate to be heat treated is subjected to quenching and tempering treatments. The heating temperature for quenching treatment is 780°C, and the holding time for quenching treatment is 40 minutes; the heating temperature for tempering treatment is 220°C, and the holding time for tempering treatment is 25 minutes. After tempering treatment, it is slowly cooled on a cooling bed to obtain a dual-phase wear-resistant steel.

[0067] Example 2

[0068] A dual-phase wear-resistant steel, based on the total mass of the dual-phase wear-resistant steel, has 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 remainder of Fe and other inevitable trace elements. The metallographic structure of the dual-phase wear-resistant steel includes 27 vol% ferrite and 72 vol% martensite.

[0069] The above-mentioned dual-phase wear-resistant steel is prepared by the following steps:

[0070] The molten iron is successively subjected to KR desulfurization, converter steelmaking, LF refining and continuous casting to obtain continuous casting billets. The thickness of the continuous casting billet is 230 mm and the width of the continuous casting billet is 1600 mm. Among them, the temperature of the converter argon station is 1524°C, the LF furnace refining time of the molten steel is 43 min, the superheat of the tundish is 12°C, and the continuous casting billet drawing speed is 1.05 m / min.

[0071] The continuous casting slab is slowly cooled in the finished product warehouse for 12 hours and then loaded into the furnace for heating treatment. The setting temperature of the soaking section of the heating furnace is 1235℃. The total time of the steel plate in the furnace is 202 minutes, and the heated slab is obtained.

[0072] The heated slab was subjected to 7 passes of rough rolling to obtain a rough rolled slab, and the surface temperature of the rough rolled slab was measured to be 1136°C.

[0073] The rough-rolled slab was subjected to finish rolling to obtain a finish-rolled steel plate, and the surface temperature of the finish-rolled steel plate was 912°C.

[0074] The steel plate after finishing rolling is cooled by layer cooling process and then coiled. The average coiling temperature is 607℃. The steel coil is sent to the finished product warehouse for packaging and printing. It is slowly cooled to room temperature in the slow cooling box. The hot rolled steel coil specification is 4.0mm×1600mm. The coiled steel coil is then cut horizontally to obtain the steel plate to be heat treated.

[0075] The steel plate to be heat treated is subjected to quenching and tempering treatments. The heating temperature for quenching treatment is 780°C, and the holding time for quenching treatment is 40 minutes; the heating temperature for tempering treatment is 220°C, and the holding time for tempering treatment is 25 minutes. After tempering treatment, it is slowly cooled on a cooling bed to obtain a dual-phase wear-resistant steel.

[0076] Example 3

[0077] A dual-phase wear-resistant steel, based on the total mass of the dual-phase wear-resistant steel, has 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 remainder is Fe and other inevitable trace elements, and the metallographic structure of the dual-phase wear-resistant steel includes 30 vol% ferrite and 69 vol% martensite.

[0078] The above-mentioned dual-phase wear-resistant steel is prepared by the following steps:

[0079] The molten iron is successively subjected to KR desulfurization, converter steelmaking, LF refining and continuous casting to obtain continuous casting billets. The thickness of the continuous casting billet is 230 mm and the width of the continuous casting billet is 1600 mm. Among them, the temperature of the converter argon station is 1527°C, the LF furnace refining time of the molten steel is 46 min, the superheat of the ladle is 14°C, and the continuous casting billet drawing speed is 1.08 m / min.

[0080] The continuous casting slab was slowly cooled in the finished product warehouse for 13 hours and then loaded into the furnace for heating treatment. The setting temperature of the soaking section of the heating furnace was 1238°C. The total time of the steel plate in the furnace was 195 minutes, and the heated slab was obtained.

[0081] The heated slab was subjected to 7 rough rolling passes to obtain a rough rolled slab, and the surface temperature of the rough rolled slab was measured to be 1135°C.

[0082] The rough-rolled slab was subjected to finish rolling to obtain a finish-rolled steel plate, and the surface temperature of the finish-rolled steel plate was 905°C.

[0083] The steel plate after finishing rolling is cooled by layer cooling process and then coiled. The average coiling temperature is 600℃. The steel coil is sent to the finished product warehouse for packaging and printing. It is slowly cooled to room temperature in the slow cooling box. The hot rolled steel coil specification is 4.0mm×1600mm. The coiled steel coil is then cut horizontally to obtain the steel plate to be heat treated.

[0084] The steel plate to be heat treated is subjected to quenching and tempering treatments. The heating temperature for quenching treatment is 780°C, and the holding time for quenching treatment is 40 minutes; the heating temperature for tempering treatment is 220°C, and the holding time for tempering treatment is 25 minutes. After tempering treatment, it is slowly cooled on a cooling bed to obtain a dual-phase wear-resistant steel.

[0085] Comparative Example 1

[0086] The only difference between this comparative example and Example 1 is that the quenching temperature during the preparation process is 700° C., and the other raw materials and preparation process remain the same as those of Example 1. The metallographic structure of the steel is mainly ferrite+pearlite.

[0087] Comparative Example 2

[0088] The difference between this comparative example and Example 1 is that the quenching temperature during the preparation process is 880° C., and the other raw materials and the preparation process remain the same as those of Example 1. The metallographic structure of the steel is tempered martensite.

[0089] Comparative Example 3

[0090] The only difference between this comparative example and Example 1 is that the tempering temperature during the preparation process is 600° C., and the other raw materials and the preparation process remain the same as those of Example 1. The metallographic structure of the steel is ferrite+tempered troostite.

[0091] Test Section

[0092] The samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance tests, tensile tests and hardness tests. The tensile test was conducted in accordance with GB / T 228.1-2010, and the hardness test was conducted in accordance with GB / T 231.1-2009. The results are shown in Table 1.

[0093] Table 1 Performance of samples of Examples 1-3 and Comparative Examples 1-3

[0094]

[0095]

[0096] As shown in Table 1, the yield strength ratio of the wear-resistant steel plates of Examples 1-3 reached about 0.58, the elongation was ≥11%, and the surface Brinell hardness reached about 325 HBW. In Comparative Example 1, the quenching temperature was lowered, and the degree of austenitization during the heating process decreased, resulting in 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°C, and the proportion of martensite increased and the proportion of ferrite decreased after quenching, resulting in an increase in tensile strength and yield strength ratio; in Comparative Example 3, the tempering temperature was increased to 600°C, and no martensite was found in the organization, and the strength and hardness decreased significantly.

[0097] The dual-phase wear-resistant steel of the present application has less precious alloy addition, low production cost, lower yield strength to ensure good processing and forming performance, and higher tensile strength to ensure the wear resistance of the material. It is particularly suitable for making parts with more complex structures and has good application prospects.

[0098] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A dual-phase wear-resistant steel, characterized in that: The metallographic structure of the dual-phase wear-resistant steel includes ferrite and martensite. Based on the total mass of the dual-phase wear-resistant steel, the components of the dual-phase wear-resistant steel include: C: 0.18% to 0.22%, Si: 0.10% to 0.20%, Mn: 1.1% to 1.30%, P: ≤0.015%, S: ≤0.002%, Cr: 0.25% to 0.35%, Ti: 0.01% to 0.03%, Als: 0.02% to 0.06%, Nb: 0.015% to 0.025%, and the remainder of Fe and inevitable trace elements.

2. The dual-phase wear-resistant steel according to claim 1, characterized in that: The metallographic structure of the dual-phase wear-resistant steel includes 25 vol% to 35 vol% of ferrite and 65 vol% to 75 vol% of martensite.

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

65.

4. A method for preparing the dual-phase wear-resistant steel according to any one of claims 1 to 3, characterized in that: The steps include: The molten steel after desulfurization, converter smelting and refining is continuously cast to obtain a continuous casting billet; Heat-treating the continuous casting billet to obtain a heated continuous casting billet; Rough rolling the heated continuous casting billet to obtain a rough rolled slab; Finish rolling the rough-rolled slab to obtain a finish-rolled steel plate; The finish-rolled steel plate is coiled and cross-cut in sequence to obtain a steel plate to be heat-treated; The dual-phase wear-resistant steel is obtained by subjecting the steel plate to be heat treated to quenching treatment and low-temperature tempering treatment, wherein the heating temperature of the quenching treatment is 20° C. to 30° C. below AC3.

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

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

7. The preparation method according to claim 4, characterized in that: In the step of heating the continuous casting billet to obtain the heated continuous casting billet, the heating treatment temperature is 1220° C. to 1280° C., and the heating treatment time is 170 min to 230 min.

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°C to 1140°C.

9. The preparation method according to claim 4, characterized in that: In the step of performing finish rolling on the rough-rolled slab to obtain the finish-rolled steel plate, the surface temperature of the finish-rolled steel plate is 880°C to 950°C.

10. The preparation method according to claim 4, characterized in that: In the step of sequentially coiling and cross-cutting the finish-rolled steel plate to obtain the steel plate to be heat-treated, the coiling temperature is 580°C to 650°C.

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