High-strength high-tensile ratio cold-rolled steel sheet and manufacturing method thereof

Abstract

The invention provides a high-strength and high-yield ratio cold-rolled steel sheet and a manufacturing method thereof. The high-strength and high-yield ratio cold-rolled steel sheet comprises the following chemical components by the weight percentage: C: 0.08 percent to 0.14 percent, Si: 0.4 percent to 1.0 percent, Mn: 1.2 percent to 2.0 percent, P: less than or equal to 0.03 percent, S: less than or equal to 0.02 percent, N: less than or equal to 0.008 percent, Al: 0.02 percent to 0.06 percent, Nb: 0.01 percent to 0.03 percent, and the rest are Fe and inevitable impurities. The high-strength and high-yield ratio cold-rolled steel sheet is manufactured through processes, such as final rolling at normal temperature, coiling at low temperature, heating and heat preservation at quite high temperature, quick cooling and the like. The yield strength of the cold-rolled steel sheet is more than or equal to 500Mpa, the tensile strength is more than or equal to 600Mpa and the yield ratio is more than or equal to 0.80; therefore, the steel sheet can meet the requirements of the automobile manufacturing industry for high-yield ratio steel sheets with higher strength.

Description

technical field [0001] The invention relates to the field of steel products, in particular to cold-rolled steel plates, and more particularly to a high-strength, high-yield ratio cold-rolled steel plate and a manufacturing method thereof. Background technique [0002] The automotive industry requires the use of high-strength steel plates to improve safety performance, reduce weight and save energy. For example, the structure of an automobile body is critical to protecting the safety of occupants, and a large number of high-strength steel plates are required. Generally, the forming of automotive structural parts is relatively simple, and the requirements for steel formability are not particularly high. However, due to the small amount of deformation and low degree of work hardening, the requirements for the original strength of the steel plate are high, otherwise it is difficult to ensure that the body has sufficient strength. Therefore, cold-rolled steel sheets for automotiv...

AI Technical Summary

Problems solved by technology

Using this strengthening mechanism, if the yield strength of this type of steel reaches more than 500MPa, it is necessary to add a lot of microalloying elements, resulting in a significant increase in cost: for example, when the addition of Nb reaches more than 0.05%, its strengthening effect reaches the plateau area, improving The strengthening effect of the added amount is not obvious; although Ti does not have the weakening of the strengthening effect, it is easy to react with impurity elements such as N, O, S, P in the steel, resulting in fluctuations in the strengthening effect, which is not conducive to the stability of the strength.

Therefore, when making the yield strength of traditional microalloyed steel reach more than 500Mpa, it encounters the bottleneck of cost and stability

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