Economical 900MPa-grade ultrahigh-strength quenched and tempered steel plate and production method thereof

Abstract

The invention relates to an economical 900MPa-grade ultrahigh-strength quenched and tempered steel plate. The steel plate comprises the following chemical components in percentage by mass: 0.155-0.175% of C, 0.10-0.30% of Si; 1.20-1.40% of Mn, less than or equal to 0.013% of P, less than or equal to 0.003% of S, 0.020-0.030% of Nb, 0.010-0.020% of Ti, 0.20-0.40% of Cr, 0.30-0.40% of Mo, 0.0010-0.0020% of B, 0.015-0.050% of Als, and the balance of Fe and other inevitable impurities. The invention further relates to a production method of the economical 900MPa-grade ultrahigh-strength quenched and tempered steel plate. In the heating process, a continuous casting billet is heated in a heating furnace, a high-temperature rolling and heating process is adopted, it is ensured that all alloy elements are completely dissolved, the temperature of a heating section is 1230-1270 DEG C, the temperature of a soaking section is 1210-1250 DEG C, and the total heating time coefficient is 9-10 min/cm.By optimizing the component design and improving the process, the 900MPa-grade ultrahigh-strength quenched and tempered steel plate which is excellent in strength and toughness, uniform in internal structure, good in welding performance and low in cost is produced.

Description

technical field [0001] The invention belongs to the technical field of metallurgical rolling, and in particular relates to an economical 900MPa-grade ultrahigh-strength tempered steel plate and a production method thereof. Background technique [0002] Construction machinery is an important part of the machinery industry. With the development of construction machinery, the strength level of steel used is getting higher and higher. With the development of large-scale equipment and parameter limit of construction machinery, higher requirements are put forward for the strength, toughness, cold formability and weldability of steel raw materials. Great improvement. [0003] At the same time, with the wide application of 900MPa ultra-high-strength steel in the field of construction machinery, the manufacturing cost of the steel plate is also a factor that cannot be ignored in the material selection process of the steel plate. The 900MPa ultra-high-strength tempered steel plate r...

AI Technical Summary

Problems solved by technology

The trouble caused by this composition design is that the price of the steel plate is high due to the high cost of the alloy, which is not conducive to market promotion.

[0004] Chinese invention patent application CN201811192029.9 discloses "a production method of nickel-free ultra-high-strength steel plate", which is designed with high Cr, high Mo, high V, high Ceq, and no Ni content, wherein the mass percentage of Cr is 1.20-1.30 %, the mass percentage of Mo is 0.40-0.60%, and the mass percentage of V is 0.050-0.080%. Although it does not contain noble metal Ni, the overall design of the alloy cost is still high; and the carbon equivalent Ceq value is 0.57-0.67%, and the carbon equivalent value The overall high is unfavorable to the welding performance of the steel plate; the Chinese invention patent application CN201811259167.4 discloses "a small amount of microalloying elements quenched and tempered high-strength and tough medium-thick steel plate", which adopts online quenching + offline tempering heat treatment process to produce yield For high-strength steel plates with a strength ≥ 730 MPa, the steel plates produced by this method have a lower strength level and cannot meet the rapid development of the construction machinery industry; moreover, this method uses the online quenching + offline tempering process to produce high-strength toughness steel plates, which is less stable than the quenching and tempering process

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