A high-toughness weather-resistant steel plate with a yield strength of 550mpa and its preparation method

Abstract

The invention discloses a high-toughness weather-resistant steel plate with the yield strength of 550MPa and a preparation method of the high-toughness weather-resistant steel plate. The high-toughness weather-resistant steel plate is prepared from the following chemical components by weight percent: 0.05 to 0.10 percent of C, 0.10 to 0.40 percent of Si, 1.20 to 1.70 percent of Mn, less than or equal to 0.012 percent of P, less than or equal to 0.008 percent of S, 0.40 to 0.80 percent of Cr, 0.15 to 0.40 percent of Ni, 0.25 to 0.40 percent of Cu, 0.015 to 0.040 percent of Als, 0.030 to 0.070 percent of Nb, and 0.010 to 0.040 percent of Ti, and the balance of Fe and unavoidable impurities, wherein Pcm is equal to C+Si / 30+(Mn+Cu+Cr) / 20+Mo / 15+Ni / 60+V / 10+5B and less than or equal to 0.20 percent. The microscopic tissue of the weather-resistant steel plate obtained according to the method disclosed in the invention is composite-phase tissue of ferrite, granular bainite and little pearlite,the ReL is 560 to 650MPa, Rm is 680 to 780MPa, A is 22.0 to 26.0 percent, and the longitudinal Charpy V-type impact power KV2 is greater than 70J at the temperature of -40 DEG C, and the high-toughness weather-resistant steel plate has excellent welding performance, cold bending forming performance and atmospheric corrosion resistance.

Description

technical field [0001] The invention belongs to the field of iron and steel materials and their manufacture, and in particular relates to a high-toughness weather-resistant steel plate with a yield strength of 550 MPa and a preparation method thereof. Background technique [0002] Weathering steel is atmospheric corrosion-resistant steel. Due to its excellent atmospheric corrosion resistance, it is widely used in containers, railway vehicles, bridges, construction and other industries. At present, the yield strength of domestic weathering steel is still mainly 345MP and 450MPa. In recent years, with the rapid development of railway vehicles, containers and other industries, higher requirements have been put forward for the comprehensive performance of weathering steel. The use of weathering steel with higher strength can reduce the amount of steel used, reduce the weight of steel components to achieve lightweight, reduce fuel consumption and harmful gas emissions. The lowes...

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Problems solved by technology

[0003] Patent Nos. CN 102409253A, CN 101994064A, and CN 101792888A disclose weathering steels with a yield strength of 550 MPa and their manufacturing methods, all of which are designed with ultra-low carbon and high Cr content components, and the addition of Cr elements is 2.15-4.0% and 2.5-7.0% respectively , 2.50~3.50%, due to the addition of a large amount of Cr elements, on the one hand, the difficulty of steelmaking production is increased, and the manufacturing cost is also greatly increased

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