Production method of NM500D wear-resistant steel plate with high strength and high low-temperature toughness

Abstract

The invention discloses a production method of a high-strength and high-low-temperature-toughness NM500D wear-resistant steel plate. The production method comprises the following steps: heating a casting blank in a heating furnace; rolling is conducted; heat treatment; the steel comprises the following chemical components in percentage by mass: 0.281%-0.291% of C, 0.351%-0.395% of S i, 1.21%-1.26% of Mn, less than or equal to 0.014% of P, less than or equal to 0.008% of S, 0.40%-0.44% of Cr, 0.051%-0.061% of V, 0.0006%-0.0009% of B, 0.012%-0.018% of T i, 0.017%-0.027% of Nb, 0.0006%-0.0016% of Ca and 0.0005%-0.0008% of Ce. The NM500D-grade wear-resistant steel with high low-temperature toughness, high hardness, high strength and low welding crack sensitivity is obtained by designing rare earth components and matching with a proper process.

Description

Technical Field

[0001] The present invention belongs to the technical field of wear-resistant steel, and particularly relates to a production method of a high-strength NM500D wear-resistant steel plate with good low-temperature and high-temperature toughness. Background Art

[0002] Wear-resistant steel refers to special plate products specifically for use under large-area wear conditions, mainly featuring high hardness and high wear resistance. With the vigorous development of China's infrastructure construction in recent years, wear-resistant steel has been widely used in industries such as mining, construction, agriculture, and metallurgy, and is developing towards the direction of low cost, lightweight, and long life. Therefore, the research and development of new wear-resistant materials is of great significance. Compared with traditional steel plates, the NM500-grade wear-resistant steel with good low-temperature toughness can meet the service requirements in harsh environments such as low temperature and strong impact, and replace low-grade wear-resistant steel to achieve lightweight assembly of mechanical materials.

[0003] The invention with the application publication number CN 106566993A discloses an NM500 thick plate with excellent low-temperature impact toughness and its production method, which includes heating, rolling processes, and heat treatment processes; the thick plate is composed of the following components by weight percentage: C≤0.31%, Si≤0.50%, Mn≤1.60%, P≤0.015%, S≤0.010%, Cr≤1.50%, Mo≤0.50%, Ni≤1.00%, 0.020%≤Al≤0.050%, B≤0.002%, Ti≤0.020, Nb≤0.05%, V≤0.05%, and the balance is Fe and inevitable impurities. This method adopts a low carbon equivalent composition design to ensure the welding performance of the steel plate, and by adding appropriate alloying elements and suitable rolling and heat treatment processes, the produced steel plate has a uniform and fine microstructure and excellent comprehensive mechanical properties; the maximum thickness of the thick plate obtained by this method can reach 80 mm, featuring moderate strength and excellent low-temperature impact toughness at -40°C at 1 / 4 of the plate thickness, and has broad application prospects. The difference between the present invention and the above invention lies first in the obvious difference in composition design, as well as the manufacturing process and manufacturing requirements.

[0004] The invention with the publication number of CN 116555678 A discloses an NM500 grade wear-resistant steel with good low-temperature toughness and its manufacturing method, including molten steel smelting, slab continuous casting, slab heating, steel plate rolling, online quenching, and tempering heat treatment. The thickness of the steel plate is 20 - 40 mm. The present invention adopts a composition design of medium carbon, low manganese, and vanadium-nitrogen microalloying, and couples clean steel control technology, controlled rolling system, and online quenching process technology. The manufactured wear-resistant steel plate has a surface Brinell hardness ≥ 500 HB, yield strength ≥ 1400 MPa, tensile strength ≥ 1500 Mpa, qualified bending at 180 °C, and -50 °C Charpy V-notch longitudinal impact energy ≥ 45 J. The difference between the present invention and the above invention lies in the obvious difference in the composition design. The manufacturing process and manufacturing requirements are also different. The present invention has lower requirements for production and manufacturing conditions and a wider application range.

[0005] The invention with the publication number of CN 113667881 A discloses a production method of a high-performance wear-resistant steel plate NM500E. The steel plate contains the following chemical components by mass percentage: C 0.25 - 0.30, Si 0.15 - 0.35, Mn 1.40 - 1.55, P ≤ 0.010, S ≤ 0.003, Als 0.010 - 0.050, Mo 0.33 - 0.45, B 0.0012 - 0.0025, Ni 1.15 - 1.30, Cr 1.10 - 1.30, and the rest are Fe and residual elements; the steel plate has a martensite structure, hardness 483 - 497 HB, yield strength ≥ 1400 MPa, tensile strength ≥ 1500 MPa, and -40 °C V-notch low-temperature impact absorption energy ≥ 45 J. The difference between the present invention and the above invention lies in the obvious difference in the composition design. The manufacturing process and manufacturing requirements are different. The present invention has lower requirements for production and manufacturing conditions and a wider application range. The manufactured products are suitable for different thicknesses. Summary of the Invention

[0006] The purpose of the present invention is to provide a production method of a high-strength NM500D wear-resistant steel plate with high and low-temperature toughness. Through the composition design of adding rare earth and cooperating with appropriate processes, an NM500D grade wear-resistant steel with high and low-temperature toughness, high hardness, high strength, and low welding crack sensitivity is obtained.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A production method of a high-strength NM500D wear-resistant steel plate with high and low-temperature toughness of the present invention, the main production process and parameters are as follows:

[0009] Use low-S hot metal and low-sulfur scrap steel for smelting, and through converter, refining, and RH vacuum treatment to ensure the composition and molten steel gas content;

[0010] The molten steel is continuously cast into a slab with a thickness of 200 - 300 mm by a continuous caster, and the cast slab is cut off and slowly cooled. Soft reduction is applied during continuous casting to improve the quality of the cast slab; the requirements for the cast slab are [H] ≤ 1.5 ppm, [O] ≤ 30 ppm, and [N] ≤ 50 ppm;

[0011] The cast slab is fed into a heating furnace for heating. The continuous casting slab is heated through a preheating section, a heating section, and a soaking section, and the heating furnace outlet temperature is 1200 - 1230 °C;

[0012] Rolling process: A two-stage rolling process is adopted. The starting rolling temperature in the first stage is 1070 - 1180 °C, the starting rolling temperature in the second stage is 890 ± 15 °C, the total reduction ratio is ≥ 7 times, and the finishing rolling temperature is 820 ± 15 °C;

[0013] Heat treatment quenching, the quenching temperature is 880 ± 10 °C; heat treatment tempering, the tempering temperature is 200 ± 10 °C, and the tempering time is 30 ± 10 min;

[0014] The chemical composition of the said steel plate by weight percentage is C: 0.281 - 0.291%, Si: 0.351 - 0.395%, Mn: 1.21 - 1.26%, P: ≤ 0.014%, S: ≤ 0.008%, Cr: 0.40 - 0.44%, V: 0.051 - 0.061%, B: 0.0006 - 0.0009%, Ti: 0.012 - 0.018%, Nb: 0.017 - 0.027%, Ca: 0.0006

[0015] - 0.0016%, Ce: 0.0005 - 0.0008%, and the balance is Fe and unavoidable impurities.

[0016] Furthermore, the heating furnace outlet temperature for rolling the continuous casting slab is 1200 °C; the rolling of the slab adopts two-stage rolling, the finishing rolling temperature of the finish rolling is 810 °C, and it is stacked and slowly cooled after rolling; quenching process: the quenching holding temperature is 875 °C, and it is quenched after holding for 30 min; tempering process: the tempering holding temperature is 190 °C, and the tempering time is 35 min; then the said steel plate can be obtained; the metallographic structure of the steel plate is tempered martensite structure plus retained austenite.

[0017] Furthermore, the heating furnace outlet temperature for rolling the continuous casting slab is 1220 °C; the rolling of the slab adopts two-stage rolling, the finishing rolling temperature of the finish rolling is 820 °C, and it is stacked and slowly cooled after rolling; quenching process: the quenching holding temperature is 880 °C, and it is quenched after holding for 30 min; tempering process: the tempering holding temperature is 200 °C, and the tempering time is 30 min; then the said steel plate can be obtained; the metallographic structure of the steel plate is tempered martensite structure plus retained austenite.

[0018] Furthermore, the heating furnace tapping temperature for continuous casting slab rolling is 1230 °C; the slab rolling adopts two-stage rolling, the finishing rolling final rolling temperature is 830 °C, and it is stacked and slowly cooled after rolling; quenching process: the quenching holding temperature is 890 °C, and it is quenched after holding for 30 min; tempering process: the tempering holding temperature is 210 °C, and the tempering time is 25 min; then the steel plate can be obtained; the metallographic structure of the steel plate is martensite tempered structure plus retained austenite.

[0019] Furthermore, the chemical composition of the steel plate is by weight percentage: C: 0.282%, Si: 0.35%, Mn: 1.21%, P: 0.012%, S: 0.005%, Cr: 0.44%, V: 0.051%, B: 0.0007%, Ti: 0.012%, Nb: 0.017%, Ca: 0.0006%, Ce: 0.0005%, and the balance is Fe and unavoidable impurities.

[0020] Furthermore, the chemical composition of the steel plate is by weight percentage: C: 0.287%, Si: 0.382%, Mn: 1.24%, P: 0.013%, S: 0.004%, Cr: 0.44%, V: 0.061%, B: 0.0007%, Ti: 0.018%, Nb: 0.026%, Ca: 0.0009%, Ce: 0.0007%, and the balance is Fe and unavoidable impurities.

[0021] Furthermore, the chemical composition of the steel plate is by weight percentage: C: 0.291%, Si: 0.395%, Mn: 1.26%, P: 0.012%, S: 0.004%, Cr: 0.42%, V: 0.055%, B: 0.0009%, Ti: 0.015%, Nb: 0.021%, Ca: 0.0014%, Ce: 0.0008%, and the balance is Fe and unavoidable impurities.

[0022] The welding crack sensitivity index CEV ≤ 0.6 (CEV = C + Mn / 6 + (Cr + V + Mo) / 5 + (Ni + Cu) / 15).

[0023] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0024] Through the present invention, an NM500D grade low-temperature wear-resistant steel plate with a thickness of 21 - 29 mm and its production method can be obtained. Through the composition design with rare earth addition and in combination with an appropriate process, an NM500D grade wear-resistant steel with high and low temperature toughness, high hardness, high strength, and low welding crack sensitivity is obtained. The wear-resistant steel of the present invention has the characteristics of high strength, high hardness, excellent low-temperature toughness, good bendability, and low welding crack sensitivity index, which promotes the lightweight of steel usage and the low-carbon development of society, and has obvious economic and social benefits. Brief Description of the Drawings

[0025] The present invention will be further described below in conjunction with the drawings.

[0026] Figure 1 For the metallographic structure of Example 1;

[0027] Figure 2 For the metallographic structure of Example 2;

[0028] Figure 3 For the metallographic structure of Example 3. Detailed Description of the Invention

[0029] Example 1

[0030] The chemical composition of the steel plate in Example 1 is shown in Table 1. The tapping temperature of the reheating furnace for continuous casting slab rolling is 1200 °C. The slab rolling adopts two-stage rolling, and the finishing rolling temperature is 810 °C. After rolling, it is stacked and slowly cooled. Quenching process: The quenching holding temperature is 875 °C, and after holding for 30 minutes, it is quenched. Tempering process: The tempering holding temperature is 190 °C, and the tempering time is 35 minutes. Then the steel plate can be obtained. The mechanical properties of the steel plate are shown in Table 2, and the metallographic structure of the steel plate is as Figure 1 shown, and the structure is tempered martensite structure plus retained austenite.

[0031] Example 2

[0032] The chemical composition of the steel plate in Example 2 is shown in Table 1. The tapping temperature of the reheating furnace for continuous casting slab rolling is 1220 °C. The slab rolling adopts two-stage rolling, and the finishing rolling temperature is 820 °C. After rolling, it is stacked and slowly cooled. Quenching process: The quenching holding temperature is 880 °C, and after holding for 30 minutes, it is quenched. Tempering process: The tempering holding temperature is 200 °C, and the tempering time is 30 minutes. Then the steel plate can be obtained. The mechanical properties of the steel plate are shown in Table 2, and the metallographic structure of the steel plate is as Figure 1 shown, and the structure is tempered martensite structure plus retained austenite.

[0033] Example 3

[0034] The chemical composition of the steel plate in Example 3 is shown in Table 1. The tapping temperature of the reheating furnace for continuous casting slab rolling is 1230 °C. The slab rolling adopts two-stage rolling, and the finishing rolling temperature is 830 °C. After rolling, it is stacked and slowly cooled. Quenching process: The quenching holding temperature is 890 °C, and after holding for 30 minutes, it is quenched. Tempering process: The tempering holding temperature is 210 °C, and the tempering time is 25 minutes. Then the steel plate can be obtained. The mechanical properties of the steel plate are shown in Table 2, and the metallographic structure of the steel plate is as Figure 1 shown, and the structure is tempered martensite structure plus retained austenite.

[0035] Table 1: Chemical composition of the steel plates in each example (wt%)

[0036]

[0037] Table 2: Steel plate properties of each embodiment

[0038]

[0039]

[0040] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A production method of a high-strength NM500D wear-resistant steel plate with high and low temperature toughness, characterized in that: The main production processes and parameters are as follows: Smelting is carried out using low-S hot metal and low-sulfur scrap steel, and is processed through a converter, refining, and RH vacuum treatment to ensure the composition and gas content of the molten steel; The molten steel is continuously cast into slabs with a thickness of 200mm - 300mm by a continuous caster, and the cast slabs are cut off and slowly cooled. Soft reduction is applied during continuous casting to improve the quality of the cast slabs; the requirements for the cast slabs are [H] ≤ 1.5ppm, [O] ≤ 30ppm, [N] ≤ 50ppm; The cast slabs are put into a heating furnace for heating. The continuous cast slabs are heated through a preheating section, a heating section, and a soaking section, and the heating furnace outlet temperature is 1200 - 1230°C; Rolling process: Adopt a two-stage rolling process. The starting rolling temperature in the first stage is 1070 - 1180°C, the starting rolling temperature in the second stage is 890 ± 15°C, the total reduction ratio is ≥ 7 times, and the finishing rolling temperature is 820 ± 15°C; Heat treatment quenching, the quenching temperature is 880 ± 10°C; heat treatment tempering, the tempering temperature is 200 ± 10°C, and the tempering time is 30 ± 10min; The chemical composition of the said steel plate by weight percentage is C: 0.281 - 0.291%, Si: 0.351 - 0.395%, Mn: 1.21 - 1.26%, P: ≤ 0.014%, S: ≤ 0.008%, Cr: 0.40 - 0.44%, V: 0.051 - 0.061%, B: 0.0006 - 0.0009%, Ti: 0.012 - 0.018%, Nb: 0.017 - 0.027%, Ca: 0.0006 - 0.0016%, Ce: 0.0005 - 0.0008%, and the balance is Fe and unavoidable impurities.

2. The production method of the high-strength NM500D wear-resistant steel plate with high low-temperature toughness according to claim 1, characterized in that: The heating furnace outlet temperature for rolling the continuously cast slab is 1200°C; the rolling of the slab adopts two-stage rolling, the finishing rolling temperature of the finish rolling is 810°C, and it is stacked and slowly cooled after rolling; quenching process: the quenching holding temperature is 875°C, and it is quenched after holding for 30min; tempering process: the tempering holding temperature is 190°C, and the tempering time is 35min; then the said steel plate can be obtained; the metallographic structure of the steel plate is tempered martensite structure plus retained austenite.

3. The production method of the high-strength NM500D wear-resistant steel plate with high and low temperature toughness according to claim 1, characterized in that: The heating furnace outlet temperature for rolling the continuously cast slab is 1220°C; the rolling of the slab adopts two-stage rolling, the finishing rolling temperature of the finish rolling is 820°C, and it is stacked and slowly cooled after rolling; quenching process: the quenching holding temperature is 880°C, and it is quenched after holding for 30min; tempering process: the tempering holding temperature is 200°C, and the tempering time is 30min; then the said steel plate can be obtained; the metallographic structure of the steel plate is tempered martensite structure plus retained austenite.

4. The production method of the high-strength NM500D wear-resistant steel plate with high and low temperature toughness according to claim 1, characterized in that: The heating furnace outlet temperature for rolling the continuously cast slab is 1230°C; the rolling of the slab adopts two-stage rolling, the finishing rolling temperature of the finish rolling is 830°C, and it is stacked and slowly cooled after rolling; quenching process: the quenching holding temperature is 890°C, and it is quenched after holding for 30min; tempering process: the tempering holding temperature is 210°C, and the tempering time is 25min; then the said steel plate can be obtained; the metallographic structure of the steel plate is tempered martensite structure plus retained austenite.

5. The production method of the high-strength NM500D wear-resistant steel plate with high and low temperature toughness according to claim 2, characterized in that: The chemical composition of the steel plate by weight percentage is C: 0.282%, Si: 0.35%, Mn: 1.21%, P: 0.012%, S: 0.005%, Cr: 0.44%, V: 0.051%, B: 0.0007%, Ti: 0.012%, Nb: 0.017%, Ca: 0.0006%, Ce: 0.0005%, and the balance is Fe and inevitable impurities.

6. The production method of the high-strength NM500D wear-resistant steel plate with high and low temperature toughness according to claim 3, characterized in that: The chemical composition of the steel plate by weight percentage is C: 0.287%, Si: 0.382%, Mn: 1.24%, P: 0.013%, S: 0.004%, Cr: 0.44%, V: 0.061%, B: 0.0007%, Ti: 0.018%, Nb: 0.026%, Ca: 0.0009%, Ce: 0.0007%, and the balance is Fe and inevitable impurities.

7. The production method of the high-strength NM500D wear-resistant steel plate with high low-temperature toughness according to claim 4, characterized in that: The chemical composition of the steel plate by weight percentage is C: 0.291%, Si: 0.395%, Mn: 1.26%, P: 0.012%, S: 0.004%, Cr: 0.42%, V: 0.055%, B: 0.0009%, Ti: 0.015%, Nb: 0.021%, Ca: 0.0014%, Ce: 0.0008%, and the balance is Fe and inevitable impurities.

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