Weathering steel with yield strength of more than 700MPa and manufacturing method thereof

Abstract

The invention relates to Cr-containing weathering steel with the yield strength of more than 700MPa, good toughness and high corrosion resistance, and a manufacturing method thereof. The weathering steel comprises the following components in percentage by weight: 0.02 to 0.10 percent of C, 0.1 to 0.4 percent of Si, 0.3 to 1.3 percent of Mn, less than or equal to 0.01 percent of P, less than or equal to 0.006 percent of S, 0.2 to 0.5 percent of Cu, 2.5 to 10 percent of Cr, 0.2 to 1.0 percent of Ni, 0.02 to 0.06 percent of Nb, 0.01 to 0.05 percent of Al, less than or equal to 0.005 percent of N, 0.02 to 0.10 percent of Ti and the balance of Fe and inevitable impurities. A steel plate made of the steel has the yield strength of more than 700MPa and good toughness; meanwhile, the relative corrosion rate of the steel is reduced by one time compared with that of the conventional weathering steel, so the steel meets the requirement of improving the corrosion resistance of steel for railway vehicles and fulfils the aims of prolonging the service life and reducing maintenance cost.

Description

technical field [0001] The invention belongs to the field of low-alloy steel manufacturing, and relates to a high-corrosion-resistant Cr-containing weather-resistant steel with a yield strength of more than 700 MPa and excellent toughness and a manufacturing method thereof. Background technique [0002] Weathering steel, or atmospheric corrosion resistant steel. Under atmospheric service conditions, the alloy elements in the steel interact with each other, and a dense rust layer with α-FeOOH as the main component is formed on the surface, which is thermodynamically stable and does not participate in the cathodic reduction process of steel electrochemical corrosion. The enrichment of copper, chromium and other elements in the rust layer makes the rust layer have ion-selective permeation characteristics, thereby significantly improving the atmospheric corrosion resistance of weathering steel. Due to its high corrosion resistance, weathering steel is widely used in railway veh...

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Problems solved by technology

The addition of these elements, on the one hand, increases the manufacturing cost and difficulty, on the other hand, it is unfavorable to the welding and toughness of the steel plate

[0005] The steel type recorded in "Corrosion-resistant steel with excellent toughness in the heat-affected zone" (JP2004162119) published in 2004 contains C with a mass percentage content as high as 0.45-0.65%. Although the strength of the steel is improved, the weldability of the steel is greatly affected.

[0006] It can be seen that the weathering steel in the prior art can not fully meet the current use and manufacturing requirements, and it is necessary to develop a weathering steel with high corrosion resistance, high strength and economical production

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