Production method of NM400E wear-resistant steel plate with low cost and high low-temperature toughness

Abstract

The invention discloses a production method of a low-cost high-low-temperature-toughness NM400E wear-resistant steel plate. The production method comprises the steps of smelting, continuous casting, rolling and heat treatment. The heat preservation temperature is 900 + / -10 DEG C, heat preservation is conducted for 10-12 min after the whole temperature is reached, and quenching is conducted to the room temperature; the tempering temperature is 180 + / -5 DEG C, and after heat preservation is conducted for 60-70 min, the steel plate is discharged out of the furnace to be slowly cooled away from wind; the steel plate comprises the following chemical components in percentage by weight: 0.17 to 0.19 percent of C, 0.36 to 0.45 percent of S i, 1.15 to 1.19 percent of Mn, less than or equal to 0.012 percent of P, less than or equal to 0.004 percent of S, 0.008 to 0.018 percent of Ti and 0.0011 to 0.0015 percent of B. The low-temperature wear-resistant steel is extremely low in alloy component design cost and can be implemented through a simple and feasible process, and the NM400E-grade wear-resistant steel plate with high low-temperature toughness, high strength and high hardness is finally obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of wear-resistant steel, and in particular relates to a production method of a low-cost high-low temperature toughness NM400E wear-resistant steel plate. Background Art

[0002] As an important type of steel material, high-strength wear-resistant steel plates are widely used in mining machinery, vehicles, ships, bridges and other industries. With the rapid development of my country's national economy, the demand for high-strength wear-resistant plates has grown rapidly. At present, the cold bending and welding properties of domestic wear-resistant steel are poor. my country still needs to import a considerable amount of wear-resistant steel plates, especially high-strength wear-resistant plates above 400HB.

[0003] The invention with the authorization announcement number CN116904871B discloses a HB400 grade high toughness wear-resistant steel and a production method. A HB400 grade high toughness wear-resistant steel, its components and wt%: C: 0.10-0.18%, Mn: 0.2-1.3%, P≤0.020%, S≤0.010%, Al s: 0.03-0.06%, Nb: 0.010-0.02%, Ti: 0.005-0.02%, Si: ≤0.020% or B: ≤0.003% or a composite addition of the two in any proportion; production method: conventional smelting and casting into billets; heating the billets and then hot rolling; coiling and then continuously uncoiling and quenching; high-speed cooling; tempering after cross-cutting according to a fixed length; natural cooling to room temperature. The invention ensures that the product hardness HB is not less than 400, the yield strength is not less than 930MPa, the tensile strength is not less than 1100MPa, and the elongation is not less than 10%. The impact energy at -40℃ is not less than 50J, and the components are simple, and the production cost can be reduced by at least 2%. The difference between the present invention and the above invention lies in the obvious difference in the composition design. The present invention adopts a low-cost composition design, and the composition design does not contain the precious metal Nb. The present invention is a flat plate product produced by a wide and thick plate production line.

[0004] The invention with authorization announcement number CN111471928B discloses a wear-resistant steel plate with a basket-weaved martensitic metallographic structure and a production method. The chemical composition mass percentage of the wear-resistant steel plate is: C=0.15-0.25, Si=0.8-2.0, Mn=1.0-2.0, P≤0.020, S≤0.005, Ti=0.070-0.20, B=0.0010-0.0025, and the remainder is Fe and inevitable impurities; the metallographic structure of the wear-resistant steel plate is a basket-weaved martensitic structure formed by nucleation and shear growth within the original austenite crystal; the production method: steelmaking to produce slabs; rolling steel plates; offline quenching; tempering. This invention reduces the alloy content, does not use Cr, Mo, and Nb alloy elements; uses Ti oxide smelting technology; increases the tempering temperature; and flexibly produces various levels of wear-resistant steel plates, effectively improving the cold bending forming performance and welding performance of wear-resistant steel plates. The main difference between this invention and the above invention is that the composition and process are obviously different, and the thickness of the products produced by this invention and the above invention is different. This invention does not need to use the oxide metallurgy technology of the above invention.

[0005] The invention with the authorization announcement number CN103014543B discloses a production process for wear-resistant steel NM400E medium and thick plates. The production method adopted by the invention includes: converter smelting, LF refining, vacuum refining, pouring, heating of ingot, rolling, slow cooling, heat treatment and other process controls. Through reasonable chemical composition design, LF+VD process is used to ensure the cleanliness of steel, and through effective implementation of heating, rolling and tempering treatment processes, 30mm-40mm high-strength NM400E steel is successfully developed, and its yield strength is controlled at 1000-1100MPa, and the tensile strength is controlled at 1200-1300MPa; the elongation is controlled at 13%-17%; the -40℃ V-type impact energy is controlled at 60-80J; the Brinell hardness in the high-temperature tempering state is 380-420. The difference between the present invention and the above invention lies first in the obvious difference in the composition design. The present invention adopts a low-cost composition design, and the composition design does not contain precious metals such as Nb, V, Cr, Ni, and Mo. The thickness of the steel plate produced by the present invention is different from that of the above invention. Summary of the invention

[0006] The purpose of the present invention is to provide a method for producing a low-cost high-low temperature toughness NM400E wear-resistant steel plate. In order to obtain a low-cost high-toughness wear-resistant steel plate for a mining vehicle bottom plate with a thickness of 12-19 mm, the low-temperature wear-resistant steel alloy composition design cost of the present invention is extremely low, and can be implemented through a simple and easy process, and finally obtains a NM400E grade wear-resistant steel plate with high low temperature toughness, high strength and high hardness.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for producing a low-cost high-low temperature toughness NM400E wear-resistant steel plate, comprising:

[0009] 1). Smelting process

[0010] The S content of the molten iron used for smelting is ≤0.005%, the tapping temperature of the converter is ≥1620℃, and the composition of the molten steel is adjusted to the design target through refining; the vacuum treatment time in the vacuum smelting process is greater than or equal to 20 minutes, the vacuum degree is below 0.35MPa, and the state is adjusted to the soft blowing state after vacuum treatment, and the soft blowing time is greater than 12 minutes;

[0011] 2). Continuous casting process

[0012] During the continuous casting process, the protective pouring method is adopted, the steel drawing speed of the casting machine is 1.0-1.1m / min, and the steel drawing speed should be kept constant as much as possible; after the continuous casting billet is off the line, it is stacked in a windproof place for slow cooling. If the ambient temperature is below zero, insulation measures such as insulation cotton covering are required to ensure the slow cooling effect;

[0013] 3). Slab rolling process

[0014] The temperature of the continuous casting billet is 1171-1190℃; in the rolling stage, large reduction rolling is adopted as much as possible, the total reduction ratio is not less than 4, and the final rolling temperature range of the rolling is 810-830℃;

[0015] 4). Heat treatment process

[0016] The steel plate adopts quenching and low temperature tempering process:

[0017] Quenching process: holding temperature 900±10℃, hold temperature for 10-12min before quenching, quench the steel plate to room temperature;

[0018] Low temperature tempering process: tempering temperature is 180±5℃, keep warm for 60-70min after the whole reaches the temperature, then take out of the furnace and cool slowly away from wind;

[0019] The chemical composition of the steel plate is C: 0.17-0.19%, Si: 0.36-0.45%, Mn: 1.15-1.19%, P: ≤0.012%, S: ≤0.004%, Ti: 0.008-0.018%, B: 0.0011-0.0015%, and the balance is Fe and unavoidable impurities.

[0020] Furthermore, the final structure of the steel plate after heat treatment is a tempered martensite structure.

[0021] Furthermore, the chemical composition of the steel plate is C: 0.188%, Si: 0.36%, Mn: 1.19%, P: 0.012%, S: 0.003%, Ti: 0.009%, B: 0.0015% by weight, and the remainder is Fe and unavoidable impurities.

[0022] Furthermore, the chemical composition of the steel plate is C: 0.182%, Si: 0.41%, Mn: 1.17%, P: 0.012%, S: 0.002%, Ti: 0.014%, B: 0.0013% by weight, and the remainder is Fe and unavoidable impurities.

[0023] Furthermore, the chemical composition of the steel plate is C: 0.171%, Si: 0.45%, Mn: 1.15%, P: 0.011%, S: 0.004%, Ti: 0.018%, B: 0.0012% by weight, and the remainder is Fe and unavoidable impurities.

[0024] Compared with the prior art, the beneficial technical effects of the present invention are:

[0025] The present invention obtains wear-resistant steel plates with high and low temperature toughness, high strength and high hardness at extremely low production costs, thereby extending the life of the product, saving social resources and contributing to the construction of a low-carbon society. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 The metallographic structure of Example 1;

[0028] Figure 2 The metallographic structure of Example 2;

[0029] Figure 3 This is the metallographic structure of Example 3. DETAILED DESCRIPTION

[0030] The present invention aims to provide a low-cost, high-low temperature toughness NM400E wear-resistant steel plate with a thickness of 12-19 mm and a production method thereof. The low-temperature wear-resistant steel alloy composition design cost of the present invention is extremely low, and can be implemented through a simple and easy process, and a NM400E grade wear-resistant steel plate with high low temperature toughness, high strength and high hardness can be obtained.

[0031] The production method specifically comprises the following steps:

[0032] 1. Smelting process

[0033] The S content of the molten iron used for smelting is ≤0.005%, the tapping temperature of the converter is ≥1620℃, and the composition of the molten steel is adjusted to the design target through refining. The vacuum treatment time in the vacuum smelting process is greater than or equal to 20 minutes, the vacuum degree is below 0.35MPa, and the state is adjusted to soft blowing after vacuum treatment, and the soft blowing time is greater than 12 minutes.

[0034] Continuous Casting Process

[0035] During the continuous casting process, the protective pouring method is adopted, and the steel drawing speed of the casting machine is 1.0-1.1m / min, and the steel drawing speed should be kept constant as much as possible. After the continuous casting billet is off the line, it is stacked in a windproof place for slow cooling. If the ambient temperature is below zero, insulation measures such as insulation cotton covering are required to ensure the slow cooling effect.

[0036] 3. Slab rolling process

[0037] The temperature of the continuous casting billet is 1171-1190℃. In the steel rolling stage, large reduction rolling is adopted as much as possible, the total reduction ratio is not less than 4, and the final rolling temperature range of steel rolling is 810-830℃.

[0038] 4. Heat treatment process

[0039] The steel plate adopts quenching and low temperature tempering process.

[0040] Quenching process: Holding temperature is 900±10℃. After the whole body reaches the temperature, keep it warm for 10-12 minutes for quenching. The steel plate is quenched to room temperature.

[0041] Low temperature tempering process: The tempering temperature is 180±5℃. After the whole product reaches the temperature, keep it warm for 60-70 minutes and then take it out of the furnace and cool it slowly away from wind.

[0042] The final structure of the steel plate after heat treatment is tempered martensite structure.

[0043] Example 1

[0044] The chemical composition is shown in Table 1 below (weight percentage). The furnace temperature of the continuous casting billet is 1171°C. The final rolling temperature after rolling is 815°C. Quenching process: the holding temperature is 890°C, and the whole is kept warm for 10 minutes before quenching. Tempering process: the holding temperature is 177°C, and the whole is kept warm for 70 minutes before being slowly cooled out of the furnace. The steel plate can be obtained. The properties of the steel plate are shown in Table 2, and the metallographic structure is shown in Figure 1 , the structure is martensite tempered structure.

[0045] Example 2

[0046] The chemical composition is shown in Table 1 below (weight percentage). The furnace temperature of the continuous casting billet is 1185℃. The final rolling temperature after rolling is 820℃. Quenching process: the holding temperature is 900℃, and the whole is kept warm for 11 minutes before quenching. Tempering process: the holding temperature is 180℃, and the whole is kept warm for 65 minutes before being slowly cooled out of the furnace. The steel plate can be obtained. The properties of the steel plate are shown in Table 2, and the metallographic structure is shown in Figure 1 , the structure is martensite tempered structure.

[0047] Example 3

[0048] The chemical composition is shown in Table 1 below (weight percentage). The furnace temperature of the continuous casting billet is 1190℃. The final rolling temperature after rolling is 830℃. Quenching process: the holding temperature is 910℃, and the whole is kept warm for 12 minutes before quenching. Tempering process: the holding temperature is 185℃, and the whole is kept warm for 60 minutes before being slowly cooled out of the furnace. The steel plate can be obtained. The properties of the steel plate are shown in Table 2, and the metallographic structure is shown in Figure 1 , the structure is martensite tempered structure.

[0049] Table 1: Chemical composition of steel plate (wt%)

[0050]

[0051] Table 2: Steel plate properties

[0052]

[0053] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing low-cost high and low temperature toughness NM400E wear-resistant steel plate, characterized by: include: 1). Smelting process The S content of the molten iron used for smelting is ≤0.005%, the tapping temperature of the converter is ≥1620℃, and the composition of the molten steel is adjusted to the design target through refining; the vacuum treatment time in the vacuum smelting process is greater than or equal to 20 minutes, the vacuum degree is below 0.35MPa, and the state is adjusted to the soft blowing state after vacuum treatment, and the soft blowing time is greater than 12 minutes; 2). Continuous casting process During the continuous casting process, the protective pouring method is adopted, the steel drawing speed of the casting machine is 1.0-1.1m / min, and the steel drawing speed should be kept constant as much as possible; after the continuous casting billet is off the line, it is stacked in a windproof place for slow cooling. If the ambient temperature is below zero, insulation measures such as insulation cotton covering are required to ensure the slow cooling effect; 3). Slab rolling process The temperature of the continuous casting billet is 1171-1190℃; in the rolling stage, large reduction rolling is adopted as much as possible, the total reduction ratio is not less than 4, and the final rolling temperature range of the rolling is 810-830℃; 4). Heat treatment process The steel plate adopts quenching and low temperature tempering process: Quenching process: holding temperature 900±10℃, hold temperature for 10-12min before quenching, quench the steel plate to room temperature; Low temperature tempering process: tempering temperature is 180±5℃, keep warm for 60-70min after the whole reaches the temperature, then take out of the furnace and cool slowly away from wind; The chemical composition of the steel plate is C: 0.17-0.19%, Si: 0.36-0.45%, Mn: 1.15-1.19%, P: ≤0.012%, S: ≤0.004%, Ti: 0.008-0.018%, B: 0.0011-0.0015%, and the balance is Fe and unavoidable impurities.

2. The method for producing low-cost high and low temperature toughness NM400E wear-resistant steel plate according to claim 1, characterized in that: The final structure of the steel plate after heat treatment is tempered martensite structure.

3. The method for producing low-cost high and low temperature toughness NM400E wear-resistant steel plate according to claim 1, characterized in that: The chemical composition of the steel plate is C: 0.188%, Si: 0.36%, Mn: 1.19%, P: 0.012%, S: 0.003%, Ti: 0.009%, B: 0.0015% by weight, and the remainder is Fe and inevitable impurities.

4. The method for producing low-cost high and low temperature toughness NM400E wear-resistant steel plate according to claim 1, characterized in that: The chemical composition of the steel plate is C: 0.182%, Si: 0.41%, Mn: 1.17%, P: 0.012%, S: 0.002%, Ti: 0.014%, B: 0.0013% by weight, and the remainder is Fe and inevitable impurities.

5. The method for producing low-cost high and low temperature toughness NM400E wear-resistant steel plate according to claim 1, characterized in that: The chemical composition of the steel plate is C: 0.171%, Si: 0.45%, Mn: 1.15%, P: 0.011%, S: 0.004%, Ti: 0.018%, B: 0.0012% by weight, and the remainder is Fe and inevitable impurities.

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