High-strength and high-toughness wear-resistant steel for soil-contacting part and preparation method thereof

Abstract

The invention belongs to the technical field of steel and iron materials, and relates to high-strength and high-toughness wear-resistant steel for a soil-contacting part and a preparation method of the wear-resistant steel. The steel comprises the following chemical components in percentage by weight: 0.38%-0.42% of C, 0.35%-0.45% of Si, 1.35%-1.45% of Mn, 0.55%-0.65% of Cr, 0.08%-0.12% of V, 0.01%-0.03% of Nb, 0.0008%-0.0015% of B, less than or equal to 0.03% of Al, less than or equal to 0.012% of S, less than or equal to 0.020% of P, less than or equal to 0.0050% of N, less than or equal to 0.0010% of O and the balance of Fe and inevitable impurities. The wear-resistant steel with high strength, high hardness, high toughness and high wear resistance is finally obtained by adopting a new component design thought and combining corresponding rolling and heat treatment processes.

Description

Technical Field

[0001] The invention belongs to the technical field of steel materials and relates to a wear-resistant steel for a soil-contacting component with high strength and high toughness and a preparation method thereof. Background Art

[0002] In recent years, with the country's increasing emphasis on agriculture, my country's agricultural arable land is gradually achieving farm centralization and large-scale development. At the same time, agricultural production methods are also moving towards full mechanization, which places higher performance requirements on the development and use of agricultural machinery. During field operations, soil-contacting parts are often subjected to impact and vibration, and are prone to problems such as wear, breakage, poor performance, and short service life, which in turn lead to serious economic losses to crops and directly affect the level of agricultural mechanization development. In the existing technology, the hardness of the soil-contacting part material obtained by quenching and low-temperature tempering ranges from 40 to 45HRC, and the wear resistance is poor, which cannot well meet the wear resistance requirements of agricultural soil-contacting parts.

[0003] Currently, to increase the service life of soil-contacting parts, many patents have been filed regarding agricultural soil-contacting materials. For example, patent CN 107803577A, a surface-strengthening coating suitable for soil-contacting parts of agricultural machinery and its preparation method, discloses that a welding wire is fixed and deposited on the surface of the soil-contacting parts of agricultural machinery by cold welding, resulting in a reinforced coating with an average hardness of 65HRC, thereby improving the surface hardness and wear resistance of the parts. Patent CN 117327957B, a cladding powder material and its application as a surface-strengthening coating for soil-contacting parts of agricultural machinery, discloses the use of cladding powder material to strengthen the surface of furrowing plow tips. After heat treatment, the hardness of the cladding layer reaches 980.7HV0.5, reducing wear by 22%. Patent CN 112159938B describes a method for preparing a highly wear-resistant field soil-contacting agricultural tool. Using cladding technology, the surface-strengthened soil-contacting component is obtained. The resulting material has a tensile strength of 1652-1710 MPa and a Rockwell hardness of 69.5-74.1 HRC. The wear weight loss after 40 minutes of wear on an M-200 wear tester is 0.0028-0.1096 g. Patent CN 115747602B describes a highly wear-resistant soil-contacting tool for tillage machinery and its preparation method. The blade of the disclosed soil-contacting tool component is made of a diamond composite material with a hardness of 58-69 HRC and an impact toughness of 1.5-3 J / cm². Using Si3N4 dual friction load of 50 N for 20 minutes, the friction mass loss is 0.71-1.87 mg.

[0004] The patent for the above-mentioned soil-contacting component material mainly uses surface modification technology to form a high-hardness, high-wear-resistant working layer on the surface of the raw material, thereby achieving the purpose of improving the wear resistance of the material. However, during field operations, the coating will be continuously worn, resulting in the exposure of the substrate. Especially during hard soil operations, the failure of the coating is more serious. In addition, due to the existence of secondary processing technology, the manufacturing cost is increased, and it cannot be widely used in agricultural components. Therefore, there is an urgent need for a new type of soil-contacting component wear-resistant material with a simple production process, high strength and high toughness. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a wear-resistant steel for soil-contacting parts with high strength and toughness and a preparation method thereof, which has the characteristics of simple production process, high strength, high toughness, high wear resistance and low cost.

[0006] The technical solution adopted by the present invention is: a wear-resistant steel for soil-contacting parts with high strength and toughness, wherein the chemical composition of the steel is as follows by weight: C: 0.38% to 0.42%, Si: 0.35% to 0.45%, Mn: 1.35% to 1.45%, Cr: 0.55% to 0.65%, V: 0.08% to 0.12%, Nb: 0.01% to 0.03%, B: 0.0008% to 0.0015%, Al: ≤0.03%, S≤0.012%, P≤0.020%, N≤0.0050%, O≤0.0010%, and the rest is Fe and unavoidable impurities.

[0007] Furthermore, the wear-resistant steel has a microstructure of tempered martensite, a yield strength of ≥1550 MPa, a tensile strength of ≥1890 MPa, a room temperature impact energy of ≥44 J, a Rockwell hardness of ≥51.5 HRC, and a weight loss due to wear of ≤1.7429 g.

[0008] The present invention also provides a method for preparing wear-resistant steel for soil-contacting parts with high strength and toughness, comprising the following key process steps:

[0009] (1) Smelting: Hot metal pretreatment, converter refining and RH furnace refining are adopted. During hot metal pretreatment, deep desulfurization technology is adopted. The converter steelmaking adopts the top and bottom blowing process. The converter end point C ≥ 0.12%, the steel tapping temperature ≥ 1630 ° C, and argon soft blowing is performed after degassing in the RH process;

[0010] (2) Continuous casting: the casting speed is 0.7-0.9 m / min, the secondary cooling water volume is 0.15-0.25 L / kg, the cooling water volume of the crystallizer is 135±10 m3 / h, the electromagnetic stirring of the crystallizer is 300±10 A / 3±1 Hz, the electromagnetic stirring of the terminal is 450±10 A / 6±1 Hz, and the soft reduction process is adopted. The billet is slowly cooled after continuous casting.

[0011] (3) Hot rolling: The hot rolling adopts a two-stage controlled rolling process, the temperature of the heating furnace is 980-1040℃, the starting rolling temperature of the recrystallization zone rolling is 960-1020℃, the first stage final rolling temperature is 860-880℃, the starting rolling temperature of the non-recrystallization zone controlled rolling is 830-850℃, and the final rolling temperature is 800-820℃;

[0012] (4) Heat treatment: The wear-resistant steel after hot rolling is quenched and tempered at low temperature. The heating temperature during quenching is 880-900℃, and after keeping warm for 40 minutes, it is water-cooled to room temperature. The temperature during low temperature tempering is 200-250℃, and after keeping warm for 60 minutes, it is air-cooled to room temperature.

[0013] Furthermore, in the smelting stage, after deep desulfurization is completed, the S in the molten iron is ≤ 0.01%, and the pure degassing time of the RH process is greater than 12 minutes.

[0014] Furthermore, in the continuous casting stage, the size of the continuous casting billet is 240 mm×300 mm, and the cooling rate is less than 0.03° C. / s.

[0015] Furthermore, during the hot rolling stage, the residual oxygen content in the heating furnace is ≤1%, and the steel is taken out of the furnace for rolling after being kept warm for 2 hours.

[0016] The effects of the various chemical elements in the present invention are mainly based on the following principles:

[0017] Carbon (C): Carbon is the primary element that determines the hardness and wear resistance of wear-resistant steel and is also the primary strengthening element in steel. High carbon content increases hardness and improves wear resistance, but higher carbon content reduces the matrix's hardenability and impact toughness. Low carbon content results in insufficient hardness and wear resistance, and also impairs casting properties. To ensure a good balance of hardness and toughness in wear-resistant steel for optimal wear resistance, the present invention controls the carbon content to 0.38% to 0.42%.

[0018] Si: Si can increase the strength of steel without significantly adversely affecting its plasticity, impact toughness, cold bending properties, or weldability. Therefore, the Si content is controlled within the range of 0.35% to 0.45%.

[0019] Mn: Mn is a commonly used strengthening element in steel. It effectively increases the strength of steel without significantly reducing its plasticity and impact toughness. It can also eliminate the hot brittleness effects of sulfur and oxygen on steel, improving its hot working properties. However, excessive Mn content can make the steel brittle and hard, and reduce its rust resistance and weldability. Therefore, in the present invention, the Mn content is controlled to 1.35% to 1.45%.

[0020] Cr: Cr is one of the basic elements of wear-resistant steel. It can improve the hardenability of steel and has the effect of solid solution strengthening and refining the matrix. It forms various carbides with C and has a significant effect on the wear resistance of steel. In the present invention, the Cr content is controlled at 0.55% to 0.65%.

[0021] Nb, V: Nb and V are common microalloying elements in wear-resistant steel. They can form fine carbonitrides with C and N, which can refine grains and strengthen the matrix, and make significant contributions to the toughening of steel. In the present invention, the Nb and V content distribution is controlled to be 0.01% to 0.03% and 0.08% to 0.12% respectively.

[0022] Al: Al can refine the grain structure of steel and improve the low-temperature toughness of steel. However, too high an Al content will affect the hot working properties of steel. Therefore, in the present invention, the Al content is controlled to be less than or equal to 0.03%.

[0023] B: B can significantly improve the hardenability and hot rolling properties of steel and increase strength, but excessive content will coarsen the grains. In the present invention, the B content is controlled within a range of 0.0008% to 0.0015%.

[0024] P: P will segregate at the grain boundaries, resulting in reduced formability and toughness of the steel, increased cold brittleness of the steel, and deteriorated welding performance. In the present invention, the P content is controlled to be less than or equal to 0.020%.

[0025] S: S is usually a harmful element in steel, causing hot brittleness in the steel and cracks during forging and rolling. The lower its content, the better. In the present invention, the S content is controlled to be less than or equal to 0.012%.

[0026] N: N is a harmful element in steel. A too high N content will result in oversized precipitates. Therefore, in the present invention, the N content is controlled to be less than or equal to 0.0050%.

[0027] The production process of the wear-resistant steel of the present invention is described as follows:

[0028] During hot rolling, a two-stage controlled rolling and controlled cooling process is adopted. The temperature of the heating furnace is 980-1040℃, and the steel is kept at this temperature for 2 hours before being rolled out of the furnace. The starting rolling temperature of the recrystallization zone rolling is 960-1020℃. Rolling is carried out above the austenite recrystallization temperature to cause the austenite to recrystallize, thereby refining the austenite grains. The first stage finishing rolling temperature is 860-880℃. The starting rolling temperature of the non-recrystallization zone controlled rolling is 830-850℃. After rolling, the deformed austenite does not recrystallize. The austenite grains are flattened and elongated, forming a large number of dislocations and deformation bands, thereby obtaining fine ferrite grains and improving the toughness of the steel. The finishing rolling temperature is 800-820℃.

[0029] The heat treatment involves quenching and low-temperature tempering. The quenching temperature is 880-900°C, held for 40 minutes, and then water-cooled to room temperature. The low-temperature tempering temperature is 200-250°C, held for 60 minutes, and then air-cooled to room temperature. Tempering within this temperature range results in the transformation of the microstructure into tempered martensite.

[0030] Obtaining excellent wear-resistant steel for soil-contacting parts is not only related to the composition design, but also to its production process. Only through reasonable composition control combined with optimized production process can the expected microstructure be obtained, thereby improving the comprehensive mechanical properties of wear-resistant steel.

[0031] The beneficial effects of the present invention are as follows: through reasonable composition design and optimized process control, the microstructure of the wear-resistant steel is tempered martensite, and a large number of fine and dispersed VC and NbC precipitates are distributed in the matrix, ensuring that the wear-resistant steel of the present invention has both high strength and high hardness, high toughness and good wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 This is the microstructure diagram of the wear-resistant steel for the soil-contacting component prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] The chemical compositions of Examples 1 to 5 are shown in Table 1, the production process parameters are shown in Table 2, and the mechanical properties and abrasion weight loss are shown in Table 3.

[0036] Example 1:

[0037] The chemical composition of the steel is as follows by weight: C: 0.42%, Si: 0.35%, Mn: 1.40%, Cr: 0.65%, V: 0.10%, Nb: 0.02%, B: 0.0010%, Al: 0.028%, N: 0.0050%, and the rest is Fe and unavoidable impurities.

[0038] The process steps are:

[0039] (1) Smelting: Pretreatment of hot metal, converter refining and RH furnace refining are carried out in sequence. KR desulfurization (deep desulfurization technology) is used for hot metal pretreatment. After KR desulfurization, the S in the hot metal is made ≤ 0.01% to ensure that the S in the final spring flat steel is ≤ 0.01%. The converter steelmaking adopts the top and bottom blowing process, the converter end point C ≥ 0.12%, and the steel tapping temperature is 1635℃. The RH furnace is used for refining, and the pure degassing time of the RH process is 13 minutes, followed by argon soft blowing.

[0040] (2) Continuous casting: The continuous casting billet size is 240mm×300mm, the billet drawing rate is 0.7m / min, the secondary cooling water volume is 0.15L / kg, and the crystallizer cooling water volume is 135m 3 / h, the crystallizer electromagnetic stirring speed is 300A / 3Hz, the end electromagnetic stirring speed is 450A / 6Hz, and a soft reduction process is adopted. After continuous casting, the ingot is slowly cooled to ensure that the cooling rate is less than 0.03℃ / s.

[0041] (3) Hot rolling: Hot rolling adopts a two-stage controlled rolling process. The temperature of the heating furnace is 980℃, the residual oxygen content in the heating furnace is ≤1%, and the steel is kept at this temperature for 2 hours before being taken out of the furnace for rolling. The starting rolling temperature of the recrystallization zone rolling is 960℃, and the final rolling temperature is 860℃; the starting rolling temperature of the non-recrystallization zone controlled rolling is 830℃, and the final rolling temperature is 810℃.

[0042] (4) Heat treatment: After hot rolling and cooling, the wear-resistant steel is subjected to quenching and low-temperature tempering. The heating temperature during quenching is 880°C, kept at this temperature for 40 minutes, and then water-cooled to room temperature; the temperature during low-temperature tempering is 200°C, kept at this temperature for 60 minutes, and then air-cooled to room temperature.

[0043] The properties and wear loss of the wear-resistant steel for soil-contacting parts produced according to the above process are shown in Table 3. The microstructure is shown in Table 3. Figure 1 shown.

[0044] Example 2:

[0045] The chemical composition of the steel is as follows by weight: C: 0.40%, Si: 0.38%, Mn: 1.35%, Cr: 0.55%, V: 0.08%, Nb: 0.03%, B: 0.0008%, Al: 0.026%, N: 0.003%, and the rest is Fe and unavoidable impurities.

[0046] The process steps are:

[0047] (1) Smelting: Hot metal pretreatment, converter refining, and RH furnace refining are carried out in sequence. During hot metal pretreatment, KR desulfurization (deep desulfurization technology) is used. After KR desulfurization, the sulfur content in the hot metal is reduced to ≤0.01% to ensure that the sulfur content in the final spring flat steel is ≤0.01%. The converter steelmaking adopts a top-bottom combined blowing process, with the converter end point C ≥0.12% and the steel tapping temperature of 1640°C. RH furnace refining is carried out, and the pure degassing time of the RH process is 15 minutes, followed by argon soft blowing.

[0048] (2) Continuous casting: The continuous casting billet size is 240mm×300mm, the billet drawing rate is 0.9m / min, the secondary cooling water volume is 0.25L / kg, and the crystallizer cooling water volume is 145m 3 / h, the crystallizer electromagnetic stirring speed is 300A / 3Hz, the end electromagnetic stirring speed is 450A / 6Hz, and a soft reduction process is adopted. After continuous casting, the ingot is slowly cooled to ensure that the cooling rate is less than 0.03℃ / s.

[0049] (3) Hot rolling: Hot rolling adopts a two-stage controlled rolling process. The temperature of the heating furnace is 1000℃, the residual oxygen content in the heating furnace is ≤1%, and the steel is kept at this temperature for 2 hours before being taken out of the furnace for rolling. The starting rolling temperature of the recrystallization zone rolling is 980℃, and the final rolling temperature is 880℃; the starting rolling temperature of the non-recrystallization zone controlled rolling is 850℃, and the final rolling temperature is 800℃.

[0050] (4) Heat treatment: After hot rolling and cooling, the wear-resistant steel is subjected to quenching and low-temperature tempering. The heating temperature during quenching is 890°C, kept at this temperature for 40 minutes, and then cooled to room temperature with water; the temperature during low-temperature tempering is 210°C, kept at this temperature for 60 minutes, and then cooled to room temperature with air.

[0051] The performance and wear weight loss of the wear-resistant steel of the soil-contacting parts produced according to the above process are shown in Table 3.

[0052] Example 3:

[0053] The chemical composition of the steel is as follows by weight: C: 0.42%, Si: 0.40%, Mn: 1.40%, Cr: 0.63%, V: 0.10%, Nb: 0.02%, B: 0.0008%, Al: 0.028%, N: 0.003%, and the rest is Fe and unavoidable impurities.

[0054] The process steps are:

[0055] (1) Smelting: Hot metal pretreatment, converter refining, and RH furnace refining are carried out in sequence. KR desulfurization (deep desulfurization technology) is used for hot metal pretreatment. After KR desulfurization, the sulfur content in the hot metal is reduced to ≤0.01% to ensure that the sulfur content in the final spring flat steel is ≤0.01%. The converter steelmaking adopts a top-bottom combined blowing process, with the converter end point C ≥0.12% and the steel tapping temperature of 1635°C. RH furnace refining is carried out, and the pure degassing time of the RH process is 13 minutes, followed by argon soft blowing.

[0056] (2) Continuous casting: The continuous casting billet size is 240mm×300mm, the billet drawing rate is 0.78m / min, the secondary cooling water volume is 0.20L / kg, and the crystallizer cooling water volume is 145m 3 / h, the crystallizer electromagnetic stirring is 310A / 3Hz, the end electromagnetic stirring is 460A / 5Hz, and a soft reduction process is adopted. After continuous casting, the ingot is slowly cooled to ensure that the cooling rate is less than 0.03℃ / s.

[0057] (3) Hot rolling: Hot rolling adopts a two-stage controlled rolling process. The temperature of the heating furnace is 1000℃, the residual oxygen content in the heating furnace is ≤1%, and the steel is kept at this temperature for 2 hours before being taken out of the furnace for rolling. The starting rolling temperature of the recrystallization zone rolling is 990℃, and the final rolling temperature is 870℃; the starting rolling temperature of the non-recrystallization zone controlled rolling is 840℃, and the final rolling temperature is 810℃.

[0058] (4) Heat treatment: After hot rolling and cooling, the wear-resistant steel is subjected to quenching and low-temperature tempering. The heating temperature during quenching is 890°C, kept at this temperature for 40 minutes, and then cooled to room temperature with water. The temperature during low-temperature tempering is 225°C, kept at this temperature for 60 minutes, and then cooled to room temperature with air.

[0059] The performance and wear weight loss of the wear-resistant steel of the soil-contacting parts produced according to the above process are shown in Table 3.

[0060] Example 4:

[0061] The chemical composition of the steel is as follows by weight: C: 0.38%, Si: 0.45%, Mn: 1.45%, Cr: 0.60%, V: 0.12%, Nb: 0.01%, B: 0.0015%, Al: 0.030%, N: 0.005%, and the rest is Fe and unavoidable impurities.

[0062] The process steps are:

[0063] (1) Smelting: Hot metal pretreatment, converter refining, and RH furnace refining are carried out in sequence. KR desulfurization (deep desulfurization technology) is used for hot metal pretreatment. After KR desulfurization, the sulfur content in the hot metal is reduced to ≤0.01% to ensure that the sulfur content in the final spring flat steel is ≤0.01%. The converter steelmaking adopts a top-bottom combined blowing process, with the converter end point C ≥0.12% and the steel tapping temperature of 1638°C. RH furnace refining is carried out, and the pure degassing time of the RH process is 18 minutes, followed by argon soft blowing.

[0064] (2) Continuous casting: The continuous casting billet size is 240mm×300mm, the billet drawing rate is 0.82m / min, the secondary cooling water volume is 0.23L / kg, and the crystallizer cooling water volume is 125m 3 / h, the crystallizer electromagnetic stirring is 290A / 3Hz, the end electromagnetic stirring is 440A / 5Hz, and a soft reduction process is adopted. After continuous casting, the ingot is slowly cooled to ensure that the cooling rate is less than 0.03℃ / s.

[0065] (3) Hot rolling: Hot rolling adopts a two-stage controlled rolling process. The temperature of the heating furnace is 1030℃, the residual oxygen content in the heating furnace is ≤1%, and the steel is kept at this temperature for 2 hours before being taken out of the furnace for rolling. The starting rolling temperature of the recrystallization zone rolling is 1010℃, and the final rolling temperature is 872℃; the starting rolling temperature of the non-recrystallization zone controlled rolling is 845℃, and the final rolling temperature is 820℃.

[0066] (4) Heat treatment: The wear-resistant steel after hot rolling and cooling is subjected to quenching + low-temperature tempering treatment. The heating temperature during quenching is 900℃, and it is kept warm for 40 minutes and then water-cooled to room temperature; the temperature during low-temperature tempering is 230℃, and it is kept warm for 60 minutes and then air-cooled to room temperature.

[0067] The performance and wear weight loss of the wear-resistant steel of the soil-contacting parts produced according to the above process are shown in Table 3.

[0068] Example 5:

[0069] The chemical composition of the steel is as follows by weight: C: 0.41%, Si: 0.42%, Mn: 1.43%, Cr: 0.60%, V: 0.08%, Nb: 0.02%, B: 0.0010%, Al: 0.026%, N: 0.005%, and the rest is Fe and unavoidable impurities.

[0070] The process steps are:

[0071] (1) Smelting: Hot metal pretreatment, converter refining, and RH furnace refining are carried out in sequence. KR desulfurization (deep desulfurization technology) is used for hot metal pretreatment. After KR desulfurization, the sulfur content in the hot metal is reduced to ≤0.01% to ensure that the sulfur content in the final spring flat steel is ≤0.01%. The converter steelmaking adopts a top-bottom combined blowing process, with the converter end point C ≥0.12% and the steel tapping temperature of 1633°C. RH furnace refining is carried out, and the pure degassing time of the RH process is 16 minutes, followed by argon soft blowing.

[0072] (2) Continuous casting: The continuous casting billet size is 240mm×300mm, the billet drawing rate is 0.85m / min, the secondary cooling water volume is 0.18L / kg, and the crystallizer cooling water volume is 125m 3 / h, the crystallizer electromagnetic stirring is 290A / 3Hz, the end electromagnetic stirring is 440A / 5Hz, and a soft reduction process is adopted. After continuous casting, the ingot is slowly cooled to ensure that the cooling rate is less than 0.03℃ / s.

[0073] (3) Hot rolling: The hot rolling adopts a two-stage controlled rolling process. The temperature of the heating furnace is 1040℃, the residual oxygen content in the heating furnace is ≤1%, and the steel is taken out of the furnace for rolling after holding for 2 hours. The starting rolling temperature of the recrystallization zone rolling is 1010℃, and the final rolling temperature is 868℃; the starting rolling temperature of the non-recrystallization zone controlled rolling is 836℃, and the final rolling temperature is 820℃.

[0074] (4) Heat treatment: The wear-resistant steel after hot rolling and cooling is subjected to quenching + low-temperature tempering treatment. The heating temperature during quenching is 900℃, and after keeping warm for 40 minutes, it is water-cooled to room temperature; the temperature during low-temperature tempering is 250℃, and after keeping warm for 60 minutes, it is air-cooled to room temperature.

[0075] The performance and wear weight loss of the wear-resistant steel of the soil-contacting parts produced according to the above process are shown in Table 3.

[0076] Table 1 Chemical composition of Examples 1-5 (mass fraction, %)

[0077] serial number C Si Mn Cr V Nb B Al N Example 1 0.42 0.35 1.40 0.65 0.10 0.02 0.0010 0.028 0.005 Example 2 0.40 0.38 1.35 0.55 0.08 0.03 0.0008 0.026 0.003 Example 3 0.42 0.40 1.40 0.63 0.10 0.02 0.0008 0.028 0.003 Example 4 0.38 0.45 1.45 0.60 0.12 0.01 0.0015 0.030 0.005 Example 5 0.41 0.42 1.43 0.60 0.08 0.02 0.0010 0.026 0.005

[0078] Table 2 Production process parameters of Examples 1 to 5

[0079]

[0080] Table 3 Mechanical properties and abrasion weight loss of Examples 1 to 5:

[0081] serial number Yield strength / MPa Tensile strength / MPa Hardness / HRC Impact energy / J Wear weight loss / Δg Example 1 1570 2001 52.4 46 1.4867 Example 2 1568 1975 52.3 45 1.5584 Example 3 1570 1932 51.8 45 1.6452 Example 4 1550 1960 51.7 44 1.6957 Example 5 1562 1890 51.5 45 1.7429

[0082] The chemical compositions of Comparative Examples 1 to 4 are shown in Table 4, and the mechanical properties of Comparative Examples 1 to 4 are shown in Table 5.

[0083] Comparative Example 1:

[0084] Compared with Example 1, the C content is reduced to 0.35%, and the others are consistent with Example 1.

[0085] Comparative Example 2:

[0086] Compared with Example 2, the C content in Comparative Example 2 is increased, and the C content is 0.47%. Other aspects are consistent with Example 2.

[0087] Comparative Example 3:

[0088] Compared with Example 3, no V element was added, and the other components were the same as those in Example 3.

[0089] Comparative Example 4:

[0090] Compared with Example 4, no Nb element was added, and the rest was consistent with Example 4.

[0091] Table 4 Chemical composition of comparative examples 1-4 (mass fraction, %)

[0092] serial number C Si Mn Cr V Nb B Al N Comparative Example 1 0.35 0.35 1.40 0.65 0.10 0.02 0.0010 0.028 0.005 Comparative Example 2 0.47 0.38 1.35 0.55 0.08 0.03 0.0008 0.026 0.003 Comparative Example 3 0.42 0.40 1.40 0.63 — 0.02 0.0008 0.028 0.003 Comparative Example 4 0.38 0.45 1.45 0.60 0.12 — 0.0015 0.030 0.005

[0093] Table 5 Mechanical properties of comparative examples 1 to 4

[0094] serial number Yield strength / MPa Tensile strength / MPa Hardness / HRC Impact energy / J Wear weight loss / Δg Comparative Example 1 1495 1873 50.7 47 1.8152 Comparative Example 2 1596 2035 52.8 43 1.4861 Comparative Example 3 1538 1890 51.2 44 1.6643 Comparative Example 4 1520 1875 51.4 43 1.7285

[0095] As shown in Table 3, Examples 1-5 all have yield strengths ≥1550 MPa, tensile strengths ≥1890 MPa, room temperature impact energies ≥44 J, Rockwell hardnesses ≥51.5 HRC, and weight losses ≤1.7429 g. Table 5 also shows that reducing carbon content reduces strength, hardness, and wear resistance; increasing carbon content reduces toughness; and reducing Nb and V also reduces mechanical properties and wear resistance.

[0096] In summary, the wear-resistant steel prepared by the technical solution of the present invention can have high strength, high hardness, high toughness and wear resistance, and is suitable for the production of soil-contacting parts with high requirements for strength, toughness and wear resistance.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A wear-resistant steel with high strength and high toughness for soil-contacting parts, characterized in that: The chemical composition of steel by weight percentage is: C: 0.38%~0.42%, Si: 0.35%~0.45%, Mn: 1.35%~1.45%, Cr: 0.55%~0.65%, V: 0.08%~0.12%, Nb: 0.01%~0.03%, B: 0.0008%~0.0015%, Al: ≤0.03%, S≤0.012%, P≤0.020%, N≤0.0050%, O≤0.0010%, and the rest is Fe and unavoidable impurities.

2. The wear-resistant steel for soil-contacting parts with high strength and toughness as claimed in claim 1, characterized in that: The wear-resistant steel has a microstructure of tempered martensite, a yield strength of ≥1550 MPa, a tensile strength of ≥1890 MPa, a room temperature impact energy of ≥44 J, a Rockwell hardness of ≥51.5 HRC, and a weight loss due to wear of ≤1.7429 g.

3. The method for preparing wear-resistant steel for soil-contacting parts with high strength and toughness according to claim 2, characterized in that: The key process steps include: (1) Smelting: Hot metal pretreatment, converter refining and RH furnace refining are adopted. During hot metal pretreatment, deep desulfurization technology is adopted. The converter steelmaking adopts the top and bottom blowing process. The converter end point C ≥ 0.12%, the steel tapping temperature ≥ 1630 ° C, and argon soft blowing is performed after degassing in the RH process; (2) Continuous casting: the casting speed is 0.7-0.9 m / min, the secondary cooling water volume is 0.15-0.25 L / kg, the cooling water volume of the crystallizer is 135±10 m3 / h, the electromagnetic stirring of the crystallizer is 300±10 A / 3±1 Hz, the electromagnetic stirring of the terminal is 450±10 A / 6±1 Hz, and the soft reduction process is adopted. The billet is slowly cooled after continuous casting. (3) Hot rolling: The hot rolling adopts a two-stage controlled rolling process, the temperature of the heating furnace is 980-1040℃, the starting rolling temperature of the recrystallization zone rolling is 960-1020℃, the first stage final rolling temperature is 860-880℃, the starting rolling temperature of the non-recrystallization zone controlled rolling is 830-850℃, and the final rolling temperature is 800-820℃; (4) Heat treatment: The wear-resistant steel after hot rolling is quenched and tempered at low temperature. The heating temperature during quenching is 880-900℃, and after keeping warm for 40 minutes, it is water-cooled to room temperature. The temperature during low temperature tempering is 200-250℃, and after keeping warm for 60 minutes, it is air-cooled to room temperature.

4. The method for preparing wear-resistant steel for soil-contacting parts with high strength and toughness according to claim 3, characterized in that: In the smelting stage, after deep desulfurization is completed, the S content in the molten iron is ≤0.01%, and the pure degassing time of the RH process is greater than 12 minutes.

5. The method for preparing wear-resistant steel for soil-contacting parts with high strength and toughness according to claim 3, characterized in that: In the continuous casting stage, the size of the continuous casting billet is 240 mm×300 mm, and the cooling rate is less than 0.03° C. / s.

6. The method for preparing wear-resistant steel for soil-contacting parts with high strength and toughness according to claim 3, characterized in that: In the hot rolling stage, the residual oxygen content in the heating furnace is ≤1%, and the steel is taken out of the furnace for rolling after being kept warm for 2 hours.

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