Rare-earth-containing 500HB-grade high-toughness wear-resistant steel plate and production method thereof

Abstract

The invention discloses a rare earth-containing 500HB-grade high-toughness wear-resistant steel plate, which is characterized by comprising the following chemical components in percentage by mass: 0.24 to 0.28 percent of C, 0.15 to 0.25 percent of Si, 0.30 to 0.55 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.0015 percent of S, 0.90 to 1.10 percent of Cr, 0.05 to 0.70 percent of Mo, 0.05 to 0.25 percent of Ni, 0.002 to 0.005 percent of Ti, 0.055 to 0.065 percent of Nb, 0.010 to 0.020 percent of V, 0.0005 to 0.0010 percent of B, 0.070 to 0.085 percent of Alt, less than or equal to 0.0050 percent of N, less than or equal to 0.0003 percent of H, less than or equal to 0.60 percent of Ceq, more than or equal to 80ppm of rare earth Ce and compared with conventional wear-resistant steel, the corrosion resistance is improved by 20%.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, in particular to a rare earth-containing 500HB-grade high-toughness wear-resistant steel plate 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. It is widely used in mining machinery, engineering machinery, coal mining machinery and other fields. In recent years, as the country's requirements for energy conservation and emission reduction have become increasingly stringent, wear materials have begun to take the path of lightweighting. Customers use high-grade wear-resistant steel, which not only requires the material to have good hardness and wear resistance, but also has higher requirements for strength and low-temperature impact toughness.

[0003] The patent with publication number CN113667881A discloses a production method of a high-performance wear-resistant steel plate NM500E. Although the low-temperature impact toughness at -40°C is ≥45J, it contains 1.15 to 1.30 Ni, and the steel plate production is extremely high, and cannot be promoted and applied.

[0004] The patented technology entitled "HB500-grade hot-rolled high-strength wear-resistant steel and its production method" with publication number CN103266269A adopts a lower alloy design, but the low-temperature impact absorption energy of the steel plate is low. On the other hand, the patent is based on hot rolling and is not suitable for wide and thick plate lines.

[0005] The patent document entitled "NM500 high-strength wear-resistant steel plate and its heat treatment process" with publication number CN102943212A uses lower alloy cost to produce NM500, but the steel plate has poor toughness and high content of P and S inclusions, which also affects the stability of the steel plate performance. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a rare earth-containing 500HB grade high-toughness wear-resistant steel plate and a production method thereof in view of the shortcomings of the above prior art.

[0007] The technical solution of the present invention to solve the above technical problems is: a rare earth-containing 500HB grade high-toughness wear-resistant steel plate, whose chemical composition and mass percentage are as follows: C: 0.24% ~ 0.28%, Si: 0.15% ~ 0.25%, Mn: 0.30% ~ 0.55%, P ≤ 0.015%, S ≤ 0.0015%, Cr: 0.90% ~ 1.10%, Mo: 0.05 ~ 0.70, Ni: 0 .05~0.25, Ti: 0.002%~0.005%, Nb: 0.055~0.065%, V: 0.010~0.020%, B: 0.0005%~0.0010%, Alt: 0.070%~0.085%, N≤0.0050%, H≤0.0003%, Ceq≤0.60, rare earth Ce≥80ppm, the rest is Fe and unavoidable impurities The present invention further defines the scheme: Preferably, its chemical composition and mass percentage are as follows: C: 0.25%-0.26%, Si: 0.15%-0.25%, Mn: 0.30%-0.40%, P≤0.015%, S≤0.0015%, Cr: 0.90%-1.00%, Mo: 0.02-0.15, Ni: 0.08%-0.18%, Ti: 0.002%-0.003%, Nb: 0.055-0.065%, V: 0.010-0.020%, B: 0.0005%-0.0010%, Alt: 0.075%-0.085%, N≤0.0050%, H≤0.0003%, Ceq≤0.60, rare earth Ce≥80ppm, and the rest is Fe and unavoidable impurities.

[0008] Preferably, its chemical composition and mass percentage are as follows: C: 0.265% ~ 0.275%, Si: 0.15% ~ 0.25%, Mn: 0.45% ~ 0.55%, P ≤ 0.015%, S ≤ 0.0015%, Cr: 1.00% ~ 1.10%, Mo: 0.15 ~ 0.55, Ni: 0.15% ~ 0.25%, Ti: 0.004% ~ 0.005%, Nb: 0.055 ~ 0.065%, V: 0.010 ~ 0.020%, B: 0.0005% ~ 0.0010%, Alt: 0.075% ~ 0.085%, N ≤ 0.0050%, H ≤ 0.0003%, Ceq ≤ 0.60, rare earth Ce ≥ 80ppm, and the rest is Fe and unavoidable impurities.

[0009] Preferably, the steel plate has a width of ≥2000 mm and a thickness of 4 to 50 mm.

[0010] The present invention provides a production method of a rare earth-containing 500HB grade high-toughness wear-resistant steel plate, which specifically includes the following processes: preparation of alloy raw and auxiliary materials - pretreatment of molten iron desulfurization - converter smelting - LF and RH - continuous casting - ingot acceptance - ingot heating - dephosphorization - rolling - air cooling - flaw detection - shot blasting - quenching - tempering; The alloys and raw materials need to be baked before production; the baking time of the tundish should be adjusted according to the month; Add new slag after slagging in molten iron pretreatment; Aluminum blocks are added during converter smelting to ensure Alt ≥ 0.015; rare earth alloys are added before converter steel is tapped; In the LF process, deoxidizer, top slag modifier and calcium carbide are added to quickly make white slag to reduce the oxygen content in the slag, and no alloy is added 15 minutes before refining and leaving the station; Throw in 15 to 20 bags of carbonized rice husk before RH enters the station. During static stirring, the argon flow rate should be controlled so that the molten steel creeps without being exposed. Throw in 8 to 10 bags of carbonized rice husk after RH leaves the station. RH outbound requirement: T.O+TN≤40ppm; The temperature of molten steel in the tundish is controlled at liquidus temperature of +30~45℃; The continuous casting uses a wire feeder to feed rare earth alloy wire from the tundish. The wire feeding speed is the Ce content of the wire fed per unit time divided by the amount of steel passed. The continuous casting billet is heated, the furnace time is 150 to 390 minutes, the soaking time is ≥30 minutes, and the steel tapping temperature is between 1190 and 1240°C; after heating, controlled rolling is carried out, the second stage rolling temperature is Tnr±10°C, and air cooling is carried out to room temperature after rolling; After rolling, off-line heat treatment is carried out and quenching is carried out in a roller hearth heat treatment furnace.

[0011] Preferably, the alloy and raw and auxiliary materials need to be baked for 2 hours before production; at the same time, the baking time of the tundish is adjusted according to the month, wherein the tundish is baked for ≥10 hours from May to September, and the tundish is baked for ≥6 hours from October to April.

[0012] Preferably, 400 kg of aluminum blocks are added during converter smelting and steel production to ensure that Alt ≥ 0.015; and 60 to 100 kg of rare earth alloy are added before the converter steel production.

[0013] Preferably, after rolling, offline heat treatment is performed, and 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 15 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. After tempering, the steel plate is taken out of the furnace and air-cooled.

[0014] Preferably, the microstructure of the steel plate is tempered martensite The beneficial effects of the present invention are as follows: the mechanical properties of the steel plate of the present invention reach the following levels: yield strength ≥1300MPa, tensile strength ≥1700MPa, elongation ≥15%, surface Brinell hardness ≥500HB, -40°C low-temperature impact energy ≥50J; Under the condition of low carbon equivalent, the present invention achieves better low-temperature impact toughness, good welding performance and certain corrosion resistance through reasonable steelmaking process optimization, composition design, micro-alloy elements and rolling-heat treatment process optimization, and the corrosion resistance is improved by 20% compared with conventional wear-resistant steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a metallographic structure photograph of a rare earth-containing 500HB grade high-toughness wear-resistant steel plate in Example 1; DETAILED DESCRIPTION Example Example

[0016] The present embodiment provides a rare earth-containing 500HB grade high-toughness wear-resistant steel plate with a width of 2500 mm and a thickness of 20 mm, and its chemical composition and mass percentage are as follows: C: 0.255%, Si: 0.18%, Mn: 0.35%, P: 0.010%, S: 0.0010%, Cr: 0.95%, Mo: 0.03%, Ni: 0.10%, Ti: 0.0025%, Nb: 0.061%, V: 0.017%, B: 0.0008%, Alt: 0.082%, N≤0.0040%, H≤0.0002%, rare earth Ce: 100 ppm, and the rest is Fe and unavoidable impurities.

[0017] This embodiment provides a production method of a rare earth-containing 500HB grade high-toughness wear-resistant steel plate, including the following processes: preparation of alloy raw and auxiliary materials - hot metal desulfurization pretreatment - converter smelting - LF and RH - continuous casting - ingot acceptance - ingot heating - dephosphorization - rolling - air cooling - flaw detection - shot blasting - quenching - tempering, specifically: Alloys and raw materials need to be baked for 2 hours before production; the baking time of the tundish should be adjusted according to the month, with the baking time of the tundish being ≥10 hours from May to September and ≥6 hours from October to April; Add new slag after slagging in molten iron pretreatment; 400 kg of aluminum blocks are added when smelting steel in the converter, Alt: 0.016; 60 kg of rare earth alloy is added before the converter is smelted.

[0018] In the LF process, deoxidizers, top slag modifiers and calcium carbide are added to quickly produce white slag to reduce the oxygen content in the slag. No alloy is added 15 minutes before refining to prevent contamination of the molten steel.

[0019] 18 bags of carbonized rice husks are thrown into the RH before it enters the station. During static stirring, the argon flow rate is controlled so that the molten steel creeps without being exposed. After leaving the station, 10 bags of carbonized rice husks are thrown into the RH. RH outbound requirement is T.O+TN 35ppm; The superheat degree of molten steel in the tundish is 40℃; The continuous casting process uses a wire feeder to feed rare earth alloy wire from the tundish, and the wire feeding speed is 0.80m / s.

[0020] The continuous casting billet was heated, the furnace time was 262 minutes, the soaking time was 40 minutes, and the steel tapping temperature was 1230°C; after heating, controlled rolling was carried out, the second stage rolling temperature was 980°C, and air-cooled to room temperature after rolling; After rolling, offline heat treatment is carried out and quenching is carried out in a roller bottom heat treatment furnace. The quenching temperature is controlled at 928±5℃, the heating rate is 1.80±0.1min / mm, and the holding time is 30min. The quenched steel plate is tempered in a car bottom heat treatment furnace. The tempering temperature is controlled at 210±5℃, the heating rate is 5.5min / mm, and the holding time is 45min. After tempering, it is taken out of the furnace and air-cooled. Example

[0021] The present embodiment provides a method for producing a rare earth-containing 500HB grade high-toughness wear-resistant steel plate with a width of 2500 mm and a thickness of 45 mm. The chemical composition and mass percentage thereof are as follows: C: 0.27%, Si: 0.22%, Mn: 0.51%, P: 0.009%, S: 0.0011%, Cr: 1.08%, Mo: 0.20%, Ni: 0.18%, Ti: 0.0045%, Nb: 0.062%, V: 0.017%, B: 0.0009%, Alt: 0.080%, N≤0.0040%, H≤0.0002%, rare earth Ce: 108 ppm, and the rest is Fe and unavoidable impurities.

[0022] The manufacturing method includes the following processes: preparation of alloy raw materials and auxiliary materials - pretreatment of molten iron desulfurization - converter smelting - LF and RH - continuous casting - ingot acceptance - ingot heating - dephosphorization - rolling - air cooling - flaw detection - shot blasting - quenching - tempering, specifically: Alloys and raw materials need to be baked for 2 hours before production; the baking time of the tundish should be adjusted according to the month, with the baking time of the tundish being ≥10 hours from May to September and ≥6 hours from October to April; Add new slag after slagging in molten iron pretreatment; When smelting steel in the converter, add 400 kg of aluminum blocks to ensure Alt: 0.016; add 70 kg of rare earth alloy before the converter taps the steel.

[0023] In the LF process, deoxidizers, top slag modifiers and calcium carbide are added to quickly produce white slag to reduce the oxygen content in the slag. No alloy is added 15 minutes before refining to prevent contamination of the molten steel.

[0024] 18 bags of carbonized rice husks are thrown into the RH before it enters the station. During static stirring, the argon flow rate is controlled so that the molten steel creeps without being exposed. After leaving the station, 10 bags of carbonized rice husks are thrown into the RH. RH outbound requirement T.O+TN: 35ppm; The superheat of molten steel in the tundish is 38℃; The continuous casting uses a wire feeder to feed the rare earth alloy wire from the tundish, and the wire feeding speed is 0.85m / s; The continuous casting billet was heated, the furnace time was 352 minutes, the soaking time was 35 minutes, and the steel tapping temperature was 1235°C; after heating, controlled rolling was carried out, the second stage rolling temperature was 965°C, and air-cooled to room temperature after rolling; After rolling, offline heat treatment is carried out and quenching is carried out in a roller bottom heat treatment furnace. The quenching temperature is controlled between 925±5℃, the heating rate is 1.80±0.1min / mm, and the holding time is 35min. The quenched steel plate is tempered in a car bottom heat treatment furnace. The tempering temperature is controlled at 210℃, the heating rate is 5.5min / mm, and the holding time is 75min. After tempering, it is taken out of the furnace and air-cooled.

[0025] The mechanical properties of the steel plates prepared in Examples 1 and 2 were tested, wherein the strength was measured according to the room temperature tensile test method for metal materials in GB / T228-2002, the low temperature impact toughness was measured according to the metal Charpy V-notch impact test method in GB / T 229-2007, and the hardness was measured according to the GB / T231.1-2009 method. The performance test results are shown in Table 1.

[0026] Table 1 Mechanical properties of the steel plate of the present invention Example Yield strength / MPa Tensile strength / MPa Elongation A50 / % -40℃ impact energy KV2 / J Surface hardness / HB Corrosion rate μm / Y 1 1341 1710 16 78 516 43.3 2 1305 1723 15 66 506 42.1 contrast 1259 1690 14 30 502 56.5 It can be seen from Table 1 that the wear-resistant steel of the present invention has a yield strength of ≥1300MPa, a tensile strength of ≥1700MPa, an elongation of ≥15%, a surface Brinell hardness of ≥500HB, and a low-temperature impact energy of -40°C of ≥50J. It can be seen that the wear-resistant steel of the present invention has good plasticity and wear resistance, as well as good low-temperature impact toughness and corrosion resistance.

[0027] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A rare earth-containing 500HB grade high-toughness wear-resistant steel plate, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.24%~0.28%, Si: 0.15%~0.25%, Mn: 0.30%~0.55%, P≤0.015%, S≤0.0015%, Cr: 0.90%~1.10%, Mo: 0.05~0.70, Ni: 0.05~0.25, Ti: 0.002%~0.005%, Nb: 0.055~0.065%, V: 0.010~0.020%, B: 0.0005%~0.0010%, Alt: 0.070%~0.085%, N≤0.0050%, H≤0.0003%, Ceq≤0.60, rare earth Ce≥80ppm, and the rest are Fe and unavoidable impurities.

2. The rare earth-containing 500HB grade high-toughness wear-resistant steel plate according to claim 1, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.25%~0.26%, Si: 0.15%~0.25%, Mn: 0.30%~0.40%, P≤0.015%, S≤0.0015%, Cr: 0.90%~1.00%, Mo: 0.02~0.15, Ni: 0.08%~0.18%, Ti: 0.002%~0.003%, Nb: 0.055~0.065%, V: 0.010~0.020%, B: 0.0005%~0.0010%, Alt: 0.075%~0.085%, N≤0.0050%, H≤0.0003%, Ceq≤0.60, rare earth Ce≥80ppm, and the rest are Fe and unavoidable impurities.

3. The rare earth-containing 500HB grade high-toughness wear-resistant steel plate according to claim 1, characterized in that: Its chemical composition and mass percentage are as follows: C: 0.265%~0.275%, Si: 0.15%~0.25%, Mn: 0.45%~0.55%, P≤0.015%, S≤0.0015%, Cr: 1.00%~1.10%, Mo: 0.15~0.55, Ni: 0.15%~0.25%, Ti: 0.004%~0.005%, Nb: 0.055~0.065%, V: 0.010~0.020%, B: 0.0005%~0.0010%, Alt: 0.075%~0.085%, N≤0.0050%, H≤0.0003%, Ceq≤0.60, rare earth Ce≥80ppm, and the rest are Fe and unavoidable impurities.

4. The rare earth-containing 500HB grade high-toughness wear-resistant steel plate according to claim 1, characterized in that: The steel plate has a width of ≥2000 mm and a thickness of 4 to 50 mm.

5. The method for producing a rare earth-containing 500HB grade high-toughness wear-resistant steel plate according to any one of claims 1 to 4, characterized in that: The specific process includes the following: preparation of alloy raw materials and auxiliary materials - hot metal desulfurization pretreatment - converter smelting - LF and RH - continuous casting - ingot acceptance - ingot heating - dephosphorization - rolling - air cooling - flaw detection - shot blasting - quenching - tempering; The alloys and raw materials need to be baked before production; the baking time of the tundish should be adjusted according to the month; Add new slag after slagging in molten iron pretreatment; Aluminum blocks are added during converter smelting to ensure Alt ≥ 0.015; rare earth alloys are added before converter steel is tapped; In the LF process, deoxidizer, top slag modifier and calcium carbide are added to quickly make white slag to reduce the oxygen content in the slag, and no alloy is added 15 minutes before refining and leaving the station; Throw in 15 to 20 bags of carbonized rice husk before RH enters the station. During static stirring, the argon flow rate should be controlled so that the molten steel creeps without being exposed. Throw in 8 to 10 bags of carbonized rice husk after RH leaves the station. RH outbound requirement: T.O+TN≤40ppm; The temperature of molten steel in the tundish is controlled at liquidus temperature of +30~45℃; The continuous casting uses a wire feeder to feed rare earth alloy wire from the tundish. The wire feeding speed is the Ce content of the wire fed per unit time divided by the amount of steel passed. The continuous casting billet is heated, the furnace time is 150 to 390 minutes, the soaking time is ≥30 minutes, and the steel tapping temperature is between 1190 and 1240°C; after heating, controlled rolling is carried out, the second stage rolling temperature is Tnr±10°C, and air cooling is carried out to room temperature after rolling; After rolling, off-line heat treatment is carried out and quenching is carried out in a roller hearth heat treatment furnace.

6. The method for producing a rare earth-containing 500HB grade high-toughness wear-resistant steel plate according to claim 5, characterized in that: Before production, the alloy and raw and auxiliary materials need to be baked for 2 hours; at the same time, the baking time of the tundish is adjusted according to the month, with the tundish baking time being ≥10 hours from May to September and ≥6 hours from October to April.

7. The method for producing a rare earth-containing 500HB grade high-toughness wear-resistant steel plate according to claim 5, characterized in that: When smelting steel in the converter, add 400 kg of aluminum blocks to ensure that Alt ≥ 0.015; add 60 to 100 kg of rare earth alloy before the converter taps the steel.

8. The method for producing a rare earth-containing 500HB grade high-toughness wear-resistant steel plate according to claim 5, characterized in that: After rolling, offline heat treatment is carried out, and quenching is carried out 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 15 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. After tempering, it is taken out of the furnace and air-cooled.

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