Rare earth-containing high-strength wear-resistant steel plate for extremely cold region and manufacturing method therefor

Abstract

A rare earth-containing high-strength wear-resistant steel plate for an extremely cold region and a manufacturing method therefor, relating to the technical field of steel production. The steel plate comprises the following chemical components, in mass percent: C: 0.20%-0.24%, Si: 0.20%-0.35%, Mn: 0.4%-0.8%, Nb: 0.035%-0.065%, V: 0.035%-0.065%, Ti: 0.001%-0.006%, Cr: 0.3%-1.0%, B: 0.0003%-0.0020%, Alt: 0.04%-0.07%, N≤0.0050%, H≤0.0002%, P≤0.015%, S≤0.0020%, Ce≥10 ppm, with the balance being Fe and inevitable impurities. The steel plate has impact energy KV2 of 64-75 J at -60°C, yield strength of 1,236-1,260 MPa, tensile strength of 1,464-1,498 MPa, elongation A50 of 14-17%, and surface hardness of 449-458 HB.

Description

A high-strength wear-resistant steel plate containing rare earth for extremely cold areas and its preparation method Technical Field

[0001] The present invention relates to the technical field of steel production, and in particular to a high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions and a preparation method thereof. Background Art

[0002] Wear-resistant steel, due to its excellent comprehensive mechanical properties, has become the most widely used wear-resistant material in industries such as mining, machinery, metallurgy, and military. Due to the rapid development of the domestic steel industry, there are increasing orders for export mining vehicles. Some construction machinery is deployed in extremely cold regions, facing harsh working environments. This places high demands on wear-resistant steel, requiring not only good hardness, wear resistance, and yield strength, but also good low-temperature toughness.

[0003] To improve the low-temperature impact toughness of steel plates, process designers typically add a certain amount of nickel alloy to the molten steel, which significantly increases costs. Some technicians also add rare earth alloys to the molten steel, but improper addition of rare earth alloys can contaminate the molten steel and affect the mechanical properties of the steel plates.

[0004] Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions and a preparation method thereof.

[0006] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0007] A high-strength wear-resistant steel plate containing rare earths for use in extremely cold areas has the following chemical composition and mass percentages: C: 0.20%-0.24%, Si: 0.20%-0.35%, Mn: 0.4%-0.8%, Nb: 0.035%-0.065%, V: 0.035%-0.065%, Ti: 0.001%-0.006%, Cr: 0.3%-1.0%, B: 0.0003%-0.0020%, Alt: 0.04%-0.07%, N≤0.0050%, H≤0.0002%, P≤0.015%, S≤0.0020%, Ce≥10ppm, and the remainder being Fe and unavoidable impurities.

[0008] As a preferred embodiment of the high-strength wear-resistant steel plate containing rare earths for use in extremely cold regions according to the present invention, its chemical composition and mass percentage are as follows: C: 0.20% to 0.22%, Si: 0.20% to 0.31%, Mn: 0.4% to 0.6%, Nb: 0.035% to 0.058%, V: 0.035% to 0.062%, Ti: 0.001% to 0.004%, Cr: 0.3% to 0.9%, B: 0.0003% to 0.0017%, Alt: 0.04% to 0.05%, N≤0.0050%, H≤0.0002%, P≤0.015%, S≤0.0020%, Ce≥10ppm, and the rest are Fe and unavoidable impurities.

[0009] As a preferred embodiment of the high-strength wear-resistant steel plate containing rare earths for use in extremely cold regions according to the present invention, its chemical composition and mass percentage are as follows: C: 0.22% to 0.24%, Si: 0.23% to 0.35%, Mn: 0.5% to 0.8%, Nb: 0.041% to 0.065%, V: 0.039% to 0.065%, Ti: 0.003% to 0.006%, Cr: 0.5% to 1.0%, B: 0.0006% to 0.0020%, Alt: 0.05% to 0.07%, N≤0.0050%, H≤0.0002%, P≤0.015%, S≤0.0020%, Ce≥10ppm, and the rest are Fe and unavoidable impurities.

[0010] As a preferred embodiment of the high-strength wear-resistant steel plate containing rare earths for use in extremely cold regions according to the present invention, its chemical composition and mass percentage are as follows: C: 0.21% to 0.23%, Si: 0.22% to 0.32%, Mn: 0.5% to 0.7%, Nb: 0.039% to 0.062%, V: 0.038% to 0.062%, Ti: 0.002% to 0.004%, Cr: 0.5% to 0.8%, B: 0.0005% to 0.0017%, Alt: 0.05% to 0.06%, N≤ 0.0050%, H≤ 0.0002%, P≤ 0.015%, S≤ 0.0020%, Ce≥ 10ppm, and the rest are Fe and unavoidable impurities.

[0011] The present invention also provides a method for preparing high-strength wear-resistant steel plates containing rare earths for use in extremely cold regions, comprising the following steps: molten iron desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - ingot stack cooling - ingot acceptance - ingot heating - dephosphorization - rolling - air cooling - flaw detection - shot blasting - quenching - tempering - straightening - cutting and sampling - printing identification - inspection - warehousing.

[0012] As a preferred solution of the method for preparing high-strength wear-resistant steel plates containing rare earth for use in extremely cold regions according to the present invention, the mass fraction of S in the molten iron after deslagging after the molten iron desulfurization pretreatment is ≤0.0030%.

[0013] As a preferred solution of the method for preparing high-strength wear-resistant steel plates containing rare earths for use in extremely cold regions according to the present invention, 300 kg of aluminum blocks are added for deoxidation after the converter smelting.

[0014] As a preferred embodiment of the method for preparing high-strength wear-resistant steel plates containing rare earth for use in extremely cold regions according to the present invention, rare earth alloys are added in the RH refining before vacuum treatment, 5 to 15 minutes after vacuum treatment, and after the vacuum treatment.

[0015] As a preferred solution of the method for preparing the high-strength wear-resistant steel plate containing rare earth for extremely cold regions according to the present invention, the intermediate package baking time in the continuous casting process is ≥5 hours.

[0016] As a preferred embodiment of the method for preparing high-strength wear-resistant steel plates containing rare earths for extremely cold regions according to the present invention, weak controlled rolling is adopted in the rolling process, and the final rolling temperature is ≤910°C, the quenching temperature is 870-930°C, and the tempering temperature is 140-240°C.

[0017] The beneficial effects of the present invention are:

[0018] (1) The present invention eliminates Ni alloy from the chemical composition of molten steel and adds a certain amount of rare earth alloy before RH vacuum treatment, after a period of vacuum treatment, and after the vacuum treatment. By adding rare earth alloy in steps, deep deoxidation is carried out, inclusions are fully modified, and the number of inclusions is reduced, thereby ensuring the hardness, wear resistance and yield strength of the steel plate in extremely cold areas and reducing the preparation cost.

[0019] (2) The steel plate prepared by the present invention has an impact energy KV2 of 64 to 75 J at -60°C, a yield strength of 1236 to 1260 MPa, a tensile strength of 1464 to 1498 MPa, an elongation A50 of 14 to 17%, and a surface hardness of 449 to 458 HB. DETAILED DESCRIPTION

[0020] In order to make the contents of the present invention more clearly understood, the present invention is further described below in detail based on specific implementation methods in conjunction with the accompanying drawings.

[0021] Example 1: This example provides a high-strength wear-resistant steel plate containing rare earths for use in extremely cold regions, whose chemical composition and mass percentages are as follows: C: 0.22%, Si: 0.21%, Mn: 0.50%, Nb: 0.055%, V: 0.050%, Ti: 0.003%, Cr: 0.40%, B: 0.0008%, Alt: 0.055%, N≤0.0050%, H: 0.0001%, P: 0.012%, S: 0.0008%, Ce: 15ppm, and the rest is Fe and unavoidable impurities.

[0022] The preparation method of the above-mentioned high-strength wear-resistant steel plate containing rare earth for extremely cold areas is as follows: molten iron desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - ingot stack cooling - ingot acceptance - ingot heating - dephosphorization - rolling - air cooling - flaw detection - shot blasting - quenching - tempering - straightening - cutting, sampling - printing marking - inspection - warehousing.

[0023] Among them, the mass fraction of S in the molten iron after slag removal after molten iron desulfurization pretreatment is ≤0.0030%. 300 kg of aluminum blocks need to be added for deoxidation after converter smelting. The alloy needs to be baked in advance when adding the alloy in LF. In RH refining, 30 kg of rare earth alloy is added before vacuum treatment, 8 minutes after vacuum treatment, and after the end of vacuum treatment. After the RH vacuum treatment is completed and rare earth is added, static stirring is carried out for 13 minutes. The intermediate ladle baking time during the continuous casting process is 5.5 hours. Weak controlled rolling is adopted in the rolling process, and the final rolling temperature is 902 ° C, the quenching temperature is 870 ° C, and the tempering temperature is 210 ° C.

[0024] The mechanical properties of the steel plate are shown in Table 1.

[0025] Example 2: This embodiment provides a method for preparing a rare earth-containing high-strength wear-resistant steel plate for extremely cold regions, which is characterized by: C: 0.23%, Si: 0.22%, Mn: 0.60%, Nb: 0.060%, V: 0.048%, Ti: 0.004%, Cr: 0.75%, B: 0.0010%, Alt: 0.058%, N≤0.0050%, H: 0.0001%, P: 0.012%, S: 0.0008%, Ce: 20ppm, and the rest is Fe and unavoidable impurities.

[0026] The preparation method of the above-mentioned high-strength wear-resistant steel plate containing rare earth for extremely cold areas is as follows: molten iron desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - ingot stack cooling - ingot acceptance - ingot heating - dephosphorization - rolling - air cooling - flaw detection - shot blasting - quenching - tempering - straightening - cutting, sampling - printing marking - inspection - warehousing.

[0027] The mass fraction of sulfur in the molten iron after slag removal after desulfurization pretreatment is ≤0.0030%. 300 kg of aluminum blocks are required for deoxidation after converter smelting. The alloy must be pre-baked when adding it to the LF. During RH refining, 30 kg of rare earth alloy is added before vacuum treatment, 5 minutes after vacuum treatment, and after the vacuum treatment is completed. After the RH vacuum treatment is completed and rare earth is added, static stirring is carried out for 18 minutes. The intermediate ladle baking time during the continuous casting process is 5 hours. Weak controlled rolling is adopted during the rolling process, and the final rolling temperature is 880°C. The quenching temperature is 880°C, and the tempering temperature is 210°C.

[0028] The mechanical properties of the steel plate are shown in Table 1.

[0029] Table 1 Mechanical properties of steel plates in the examples

[0030] In addition to the above embodiments, the present invention may also have other implementation methods; any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.20% ~ 0.24%, Si: 0.20% ~ 0.35%, Mn: 0.4% ~ 0.8%, Nb: 0.035% ~ 0.065%, V: 0.035% ~ 0.065%, Ti: 0.001% ~ 0.006%, Cr: 0.3% ~ 1.0%, B: 0.0003% ~ 0.0020%, Alt: 0.04% ~ 0.07%, N ≤ 0.0050%, H ≤ 0.0002%, P ≤ 0.015%, S ≤ 0.0020%, Ce ≥ 10ppm, and the rest are Fe and unavoidable impurities.

2. The high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions according to claim 1, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.20% ~ 0.22%, Si: 0.20% ~ 0.31%, Mn: 0.4% ~ 0.6%, Nb: 0.035% ~ 0.058%, V: 0.035% ~ 0.062%, Ti: 0.001% ~ 0.004%, Cr: 0.3% ~ 0.9%, B: 0.0003% ~ 0.0017%, Alt: 0.04% ~ 0.05%, N ≤ 0.0050%, H ≤ 0.0002%, P ≤ 0.015%, S ≤ 0.0020%, Ce ≥ 10ppm, and the rest are Fe and unavoidable impurities.

3. The high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions according to claim 1, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.22% ~ 0.24%, Si: 0.23% ~ 0.35%, Mn: 0.5% ~ 0.8%, Nb: 0.041% ~ 0.065%, V: 0.039% ~ 0.065%, Ti: 0.003% ~ 0.006%, Cr: 0.5% ~ 1.0%, B: 0.0006% ~ 0.0020%, Alt: 0.05% ~ 0.07%, N ≤ 0.0050%, H ≤ 0.0002%, P ≤ 0.015%, S ≤ 0.0020%, Ce ≥ 10ppm, and the rest are Fe and unavoidable impurities.

4. The high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions according to claim 1, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.21% ~ 0.23%, Si: 0.22% ~ 0.32%, Mn: 0.5% ~ 0.7%, Nb: 0.039% ~ 0.062%, V: 0.038% ~ 0.062%, Ti: 0.002% ~ 0.004%, Cr: 0.5% ~ 0.8%, B: 0.0005% ~ 0.0017%, Alt: 0.05% ~ 0.06%, N ≤ 0.0050%, H ≤ 0.0002%, P ≤ 0.015%, S ≤ 0.0020%, Ce ≥ 10ppm, and the rest are Fe and unavoidable impurities.

5. A method for preparing a high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: Hot metal desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - ingot cooling - ingot acceptance - ingot heating - dephosphorization - rolling - air cooling - flaw detection - shot blasting - quenching - tempering - straightening - cutting, sampling - printing identification - inspection - warehousing.

6. The method for preparing a high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions according to claim 5, characterized in that: The mass fraction of S in the molten iron after slagging after the molten iron desulfurization pretreatment is ≤0.0030%.

7. The method for preparing a high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions according to claim 5, characterized in that: After the converter smelting, 300 kg of aluminum blocks were added for deoxidation.

8. The method for preparing a high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions according to claim 5, characterized in that: In the RH refining, rare earth alloy is added before vacuum treatment, after 5 to 15 minutes of vacuum treatment, and after the vacuum treatment is completed.

9. The method for preparing a high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions according to claim 5, characterized in that: The intermediate package baking time in the continuous casting process is ≥5 hours.

10. The method for preparing a high-strength wear-resistant steel plate containing rare earth for use in extremely cold regions according to claim 5, characterized in that: The rolling process adopts weak controlled rolling, and the final rolling temperature is ≤910°C, the quenching temperature is 870-930°C, and the tempering temperature is 140-240°C.

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