Rare earth treated 690MPa-grade high strength steel plate with low preheating temperature, and preparation method of steel plate

Abstract

The invention provides a rare earth treated 690MPa-grade high strength steel plate with a low preheating temperature, and a preparation method of the steel plate. The steel plate is prepared from thefollowing chemical components by mass percent: 0.09-0.15% of C, 0.30-0.45% of Si, 1.58-1.75% of Mn, less than or equal to 0.02% of P, less than or equal to 0.010% of S, 0.04-0.08% of Nb, 0.05-0.08% ofV, 0.010-0.020% of Ti, 0.20-0.40% of Cr, less than or equal to 0.030% of La, 0.020-0.050% of Alt, less than or equal to 0.005% of N and less than or equal to 0.004% of O. The 690MPa-grade high strength steel plate is prepared by adding rare but without Ni and Mo, and has the low preheating temperature, so that the cost is lowered; furthermore, by adopting rare earth treatment, the comprehensive mechanical properties are improved, the service life is prolonged, and the obtained steel plate has good economic benefit.

Description

Technical field [0001] The invention belongs to the technical field of metallurgical materials, particularly the field of high-strength steel for engineering machinery, and specifically relates to a rare-earth-treated low-preheating temperature 690MPa high-strength steel and a preparation method thereof. The steel plate has good welding performance. Background technique [0002] With the development of construction machinery in the direction of large-scale equipment, lighter weight, heavy load, etc., high-strength steel has shown broad prospects for the application of new materials in the downstream deep-processing industry chain. The amount of high-strength steel has shown an increasing trend, and the strength level has increased. Also very fast. In construction machinery products, welded structural parts account for about 50% to 70% of the weight of the whole machine. Since structural parts have to withstand complex and variable cyclic loads, steels are required to have high y...

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Problems solved by technology

[0003] The current construction machinery steels are all added with Ni and Mo, such as described by Zhang Hong et al. A quenched and tempered high-strength steel Q690 was adopted, and the composition design scheme of low carbon and Mo-Ni-B microalloying was adopted, which increased the manufacturing cost, and did not mention the preheating temperature of the quenched and tempered high-strength steel Q690; Zhao Yanqing et al. People (Zhao Yanqing et al., Microstructure and Properties of 690MPa Low Carbon Bainite Steel After Tempering, Metal Heat Treatment, Volume 35, No. 10, October 2010) described a 690MPa low carbon bainitic steel, also adopted Ni, Mo and other precious metals are used to improve the mechanical properties of steel plates, resulting in increased costs; Zhang Yunyan et al. ) introduced the chemical composition, mechanical properties, microstructure differences between online heat treatment and offline heat treatment of Q690, and also used other alloying elements such as Mo to enhance the performance of the steel plate, and did not explain its preheating temperature

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