Wear-resistant steel for easily-drilled high-toughness large-thickness artificial board and production method of wear-resistant steel

Abstract

The invention relates to the technical field of steel production, in particular to wear-resistant steel easy to drill, high in toughness and large in thickness for artificial boards and a production method thereof, and the production method comprises the steps of molten iron pretreatment, converter smelting, LF and RH refining, continuous casting, rolling cooling control, air cooling and heat treatment. In the first stage of continuous casting, the thickness of a continuous casting blank is 320 / 370 / 460 mm, the width of the continuous casting blank is 75%-85% of the width of a steel plate, and the low pulling speed of 0.2-0.65 m / min is adopted; weak water cooling is adopted, the secondary cooling specific water flow is 0.2-0.4 Kg / L, and the water ratio of the wide surface to the narrow surface is (2: 1)-(3.5: 1). According to the wear-resistant steel obtained through the method, the hardness of 10 mm under the surface is larger than or equal to 400 HB, the yield strength is larger than or equal to 850 MPa, the tensile strength is larger than or equal to 1050 MPa, the ductility is larger than or equal to 8%, and the-20 DEG C low-temperature impact And the 1 / 2 thickness hardness of the core part is 280-350 HB.

Description

Technical Field

[0001] The present invention relates to the technical field of steel production, and particularly to a wear-resistant steel for high-toughness large-thickness particleboard with easy drillability and a production method thereof. Background Art

[0002] Wear-resistant steel has excellent comprehensive mechanical properties and has become the most widely used wear-resistant material, being widely applied in fields such as mining machinery, construction machinery, coal mine machinery, and particleboard machinery. As a wear-resistant material, since the wear-resistant plate has to rub against the pressing plate, the upper surface of the steel plate should have a certain hardness, and holes need to be drilled through the steel plate for hot oil cooling inside. If the hardness of the core part is too high, it will waste drill bits and reduce processing efficiency. Therefore, it is necessary to reasonably design the sectional hardness of the steel plate and control the macrosegregation of the steel plate. For this reason, the present invention provides a wear-resistant steel for high-toughness large-thickness particleboard with easy drillability and a production method thereof. Summary of the Invention

[0003] Aiming at the above technical problems and overcoming the shortcomings of the prior art, the present invention provides a wear-resistant steel for high-toughness large-thickness particleboard with easy drillability and a production method thereof. The obtained wear-resistant steel has a hardness of ≥400 HB at 10 mm below the surface, a yield strength of ≥850 MPa, a tensile strength of ≥1050 MPa, an elongation of ≥8%, and a low-temperature impact energy of ≥17 J at -20 °C; the hardness of the core part at 1 / 2 thickness is between 280 and 350 HB.

[0004] In a first aspect, the present invention provides a production method of a wear-resistant steel for high-toughness large-thickness particleboard with easy drillability, which specifically includes the following steps: hot metal pretreatment, converter smelting, LF and RH refining, continuous casting, rolling and controlled cooling, air cooling, and heat treatment; wherein, the specific parameters in the first stage of the continuous casting include: (1) the thickness of the continuous casting billet is selected as 320 / 370 / 460 mm; (2) the width of the continuous casting billet is selected as 75%-85% of the width of the steel plate; (3) a low casting speed of 0.2-0.65 m / min is adopted; (4) weak water cooling is adopted, and the secondary cooling water ratio is 0.2-0.4 Kg / L; (5) the water ratio of the wide face to the narrow face is 2:1-3.5:1.

[0005] Furthermore, the specific parameters of the pressing process during continuous casting are: (1) the solid phase rate in the pressing interval is 40%-180%; (2) the total reduction is 510 mm; (3) the pressing interval is 4-5 pressure rolls; (4) the reduction amount of each roll is controlled at 1-3 mm.

[0006] Furthermore, after the first stage of continuous casting, the continuous casting billet is reheated, the time in the furnace is 330-470 min, the soaking time is ≥30 min, and the tapping temperature is between 1190 and 1240 °C; then controlled rolling is carried out, the starting rolling temperature in the second stage is Tnr±30 °C, and it is air-cooled to room temperature after rolling.

[0007] Furthermore, the starting rolling temperature in the second stage is Tnr ± 30°C. Descalers are used in the last two passes after the first stage rolling, with a reduction of ≥ 40 mm. The reduction in the 1st and 2nd passes of the second stage rolling is ≥ 25 mm, and the rolled product is air-cooled until it stops.

[0008] Furthermore, the heat treatment process is specifically as follows: quenching is carried out using a roller hearth heat treatment furnace, with the quenching temperature controlled between 900 and 930°C, the heating rate being 1.80 ± 0.1 min / mm, the holding time being 20 - 40 min. The quenched steel plate is tempered using a car-bottom heat treatment furnace, with the tempering temperature controlled at 200 - 220°C, the heating rate being 5.5 min / mm, the holding time being 45 - 100 min, and then air-cooled after tempering and taken out of the furnace.

[0009] Furthermore, the width of the steel plate air-cooled after tempering and taken out of the furnace is 1500 - 2700 mm, and the thickness is 60 - 120 mm.

[0010] Furthermore, the metallographic structure within 2 - 10 mm below the surface of the steel plate is martensite, and the metallographic structure at 1 / 4 and 1 / 2 of the thickness is bainite.

[0011] In a second aspect, the present invention also provides a wear-resistant steel for high-toughness, large-thickness artificial boards with easy drillability, which is prepared by using the production method described in any one of the schemes in the first aspect.

[0012] Furthermore, the chemical composition of the wear-resistant steel by mass percentage is as follows: C: 0.18% - 0.25%, Si: 0.15% - 0.35%, Mn: 0.30% - 0.55%, P ≤ 0.020%, S ≤ 0.0020%, Cr: 0.30% - 0.80%, Mo: 0.02 - 0.25, Ni: 0.05 - 0.25, Ti: 0.002% - 0.005%, Nb: 0.015 - 0.055%, B: 0.0010% - 0.0030%, Al: 0.015% - 0.065%, N ≤ 0.0050%, H ≤ 0.0003%, and the balance is Fe and unavoidable impurities.

[0013] Furthermore, the chemical composition of the wear-resistant steel by mass percentage is as follows: C: 0.21% - 0.23%, Si: 0.15% - 0.25%, Mn: 0.30% - 0.40%, P ≤ 0.015%, S ≤ 0.0015%, Cr: 0.55% - 0.65%, Mo: 0.02 - 0.05, Ni: 0.10% - 0.20%, Ti: 0.002% - 0.003%, Nb: 0.015 - 0.025%, B: 0.0010% - 0.0020%, Al: 0.070% - 0.085%, N ≤ 0.0050%, H ≤ 0.0003%, and the balance is Fe and unavoidable impurities.

[0014] The beneficial effects of the present invention are as follows:

[0015] (1) The mechanical properties of the steel plate obtained by the production method of the present invention reach the following levels: the hardness at 10 mm below the surface ≥ 400 HB, the yield strength ≥ 850 MPa, the tensile strength ≥ 1050 MPa, the elongation ≥ 8%, and the low-temperature impact energy at -20 °C ≥ 17 J; the hardness at 1 / 2 thickness of the core is between 280 and 350 HB;

[0016] (2) Through reasonable optimization of the steelmaking process, composition design, and rolling - heat treatment process optimization, the present invention realizes that the surface hardness ≥ 400 HB has certain wear resistance, and the low core hardness is beneficial for drilling. Specific embodiments

[0017] An NM400 for easily drillable high - toughness large - thickness artificial board provided in this embodiment has a width of 2200 mm and a thickness of 90 mm. Its chemical composition and mass percentage are as follows: C: 0.22%, Si: 0.20%, Mn: 0.35%, P: 0.010%, S: 0.0010%, Cr: 0.60%, Mo: 0.03%, Ni: 0.15%, Ti: 0.0025%, Nb: 0.022%, B: 0.0015%, Alt: 0.083%, N ≤ 0.0040%, H ≤ 0.0002%, and the rest is Fe and inevitable impurities.

[0018] The production method includes the following processes: hot metal pretreatment - converter smelting - LF and RH - continuous casting - rolling controlled cooling - air cooling - heat treatment. Specifically:

[0019] The thickness of the continuous casting slab is selected as 370 mm, and the width of the slab is 2070 mm;

[0020] The continuous caster adopts a low casting speed of 0.55 m / min;

[0021] The continuous caster adopts weak water cooling, the secondary cooling water ratio is 0.37 Kg / L; the water ratio of the wide face to the narrow face (in the plate thickness direction) is 2.7:1;

[0022] The continuous casting reduction adopts an extended reduction interval. The solid - phase rate in the reduction interval is 50% - 140%, and the total reduction amount is 10 mm; the reduction interval is 4 reduction rolls, and the reduction amount of each roll is controlled at 2.5 mm;

[0023] The continuous casting slab is reheated. The time in the furnace is 380 min, the soaking time is 40 min, and the tapping temperature is 1230 °C; after heating, controlled rolling is carried out. The starting rolling temperature in the second stage is 940 °C, and it is air - cooled to room temperature after rolling;

[0024] After the first-stage rolling, descaling is required for both of the next two passes, and the reduction is 42 mm; for the first and second passes of the second-stage rolling, the reduction is 28 mm.

[0025] After rolling, off-line heat treatment is carried out. Quenching is performed using a roller hearth heat treatment furnace. The quenching temperature is 920 °C, the heating rate is 1.80 ± 0.1 min / mm, the holding time is 30 min. The quenched steel plate is tempered using a car-bottom heat treatment furnace. The tempering temperature is 215 °C, the heating rate is 5.5 min / mm, the holding time is 50 min, and after tempering, it is taken out of the furnace and air-cooled.

[0026] The mechanical properties of the steel plate in this example are tested. Among them, the strength is tested according to the method of GB / T228-2002 Metallic materials - Tensile testing at ambient temperature, the low-temperature impact toughness is determined according to the method of GB / T 229-2007 Metallic materials - Charpy V-notch impact test, and the hardness is measured according to the method of GB / T231.1-2009. The test results of the properties are shown in Table 1.

[0027] Table 1 Mechanical properties of the steel plate in the embodiment of the present invention

[0028]

[0029] As can be seen from Table 1, the mechanical properties of the wear-resistant steel plate obtained by the present invention reach the following levels: the hardness at 10 mm below the surface is ≥ 400 HB, the yield strength is ≥ 850 MPa, the tensile strength is ≥ 1050 MPa, the elongation is ≥ 8%, and the low-temperature impact energy at -20 °C is ≥ 17 J; the hardness at 1 / 2 thickness of the core is between 280 and 350 HB, meeting the customer requirements.

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

Claims

1. A method for producing wear-resistant steel for easy-drilling, high-toughness and large-thickness artificial panels, characterized in that: The following steps are involved: Hot metal pretreatment, converter smelting, LF and RH refining, continuous casting, rolling controlled cooling, air cooling and heat treatment; wherein, the specific parameters of the first stage of continuous casting include: (1) the thickness of the continuous casting billet is selected as 320 / 370 / 460mm; (2) the width of the continuous casting billet is selected as 75%-85% of the width of the steel plate; (3) a low drawing speed of 0.2-0.65m / min is adopted; (4) weak water cooling is adopted, and the secondary cooling water volume is 0.2-0.4Kg / L; (5) the water ratio of the wide side to the narrow side is 2:1-3.5:

1.

2. The production method according to claim 1, characterized in that The specific parameters of the reduction process during continuous casting are: (1) the solid phase ratio in the reduction range is 40% to 180%; (2) the total reduction amount is 510 mm; (3) the reduction range is 4 to 5 pressure rollers; (4) the pressure reduction amount of each roller is controlled at 1 to 3 mm.

3. The production method according to claim 2, characterized in that: After the first stage of continuous casting, the continuous casting billet is reheated, with the furnace time being 330 to 470 minutes, the soaking time being ≥30 minutes, and the steel-out temperature being between 1190 and 1240°C; then controlled rolling is carried out, with the second stage starting rolling temperature being Tnr±30°C, and air cooling to room temperature after rolling.

4. The production method according to claim 3, characterized in that: The rolling temperature at the second stage is Tnr±30℃. Dephosphorization is carried out in two passes after the first stage rolling, and the reduction is ≥40mm. The reduction of the first and second passes of the second stage rolling is ≥25mm, and air cooling is performed after rolling.

5. The production method according to claim 4, characterized in that: The heat treatment process is specifically as follows: quenching is performed in a roller bottom heat treatment furnace, the quenching temperature is controlled between 900 and 930°C, the heating rate is 1.80±0.1min / mm, and the holding time is 20 to 40min; the quenched steel plate is tempered in a car bottom heat treatment furnace, the tempering temperature is controlled between 200 and 220°C, the heating rate is 5.5min / mm, and the holding time is 45 to 100min; and after tempering, the steel plate is taken out of the furnace and air-cooled.

6. The production method according to claim 5, characterized in that The steel plate which is taken out of the furnace and air-cooled after tempering has a width of 1500-2700 mm and a thickness of 60-120 mm.

7. The production method according to claim 6, characterized in that: The metallographic structure of the steel plate below the surface 2 to 10 mm is martensite, and the metallographic structure of 1 / 4 and 1 / 2 of the thickness is bainite.

8. A wear-resistant steel for easy-drilling, high-toughness and thick artificial board, characterized in that: The method is used for preparation according to any one of claims 1 to 7.

9. The wear-resistant steel for artificial board according to claim 8, characterized in that: The chemical composition mass percentage of the wear-resistant steel is: C: 0.18%-0.25%, Si: 0.15%-0.35%, Mn: 0.30%-0.55%, P≤0.020%, S≤0.0020%, Cr: 0.30%-0.80%, Mo: 0.02-0.25, Ni: 0.05-0.25, Ti: 0.002%-0.005%, Nb: 0.015-0.055%, B: 0.0010%-0.0030%, Al: 0.015%-0.065%, N≤0.0050%, H≤0.0003%, and the rest is Fe and unavoidable impurities.

10. The wear-resistant steel for artificial board according to claim 8, characterized in that: The chemical composition mass percentage of the wear-resistant steel is: C: 0.21%-0.23%, Si: 0.15%-0.25%, Mn: 0.30%-0.40%, P≤0.015%, S≤0.0015%, Cr: 0.55%-0.65%, Mo: 0.02-0.05, Ni: 0.10%-0.20%, Ti: 0.002%-0.003%, Nb: 0.015-0.025%, B: 0.0010%-0.0020%, Al: 0.070%-0.085%, N≤0.0050%, H≤0.0003%, and the rest is Fe and unavoidable impurities.

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