Method for Solving Edge Crack Defects of Cold-rolled High-strength Steel Above 780mpa Grade in Acid Rolling

Abstract

The invention discloses a method for solving the edge crack defect of cold-rolled high-strength steel above 780MPa grade, which comprises continuous casting, heating, rough rolling, finishing rolling, laminar cooling, coiling and slow cooling processes. The yield rate of the whole process of cold-rolled high-strength steel is ≥92.3%, the incidence rate of acid-rolled edge crack defects is ≤2.38%, the pass rate is ≥98.6%, and the fluctuation of the yield strength of the whole coil is ≤43MPa. Improves the phenomenon of coarse grains, mixed crystals and strip-like carbide precipitation at the edge of the strip steel, realizes the stability of the coil structure and properties of the strip steel, and solves the acid-rolled edge cracking of cold-rolled high-strength steel above 780MPa Defects are eliminated, the surface quality of the product is significantly improved, the yield and pass rate of the strip are increased, and the acid rolling production is stable.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for solving the edge crack defect of cold-rolled high-strength steel above 780MPa level. Background technique [0002] For cold-rolled high-strength steel of 780MPa grade and above, edge cracks often occur during acid rolling, and the coil head and tail are serious, and even the strip may be broken due to edge cracks, which seriously affects the stable production of acid rolling. The occurrence rate of edge cracking in acid rolling of high-strength steels such as 980DP and 1180MS is 40%, the yield rate of cold-rolled high-strength steels above 780Mpa is only 87.6%, and the pass rate is 95.3%. Edge fractures often occur, resulting in the need to slow down production. At present, the main methods in China are to control the reduction rate of the acid rolling process and strictly prohibit the mid-wave, but the effect is not obvious. [0003] The main causes ...

AI Technical Summary

Problems solved by technology

[0002] For cold-rolled high-strength steel of 780MPa grade and above, edge cracks often occur during acid rolling, and the coil head and tail are serious, and even the strip may be broken due to edge cracks, which seriously affects the stable production of acid rolling. The occurrence rate of edge cracking in acid rolling of high-strength steels such as 980DP and 1180MS is 40%, the yield rate of cold-rolled high-strength steels above 780Mpa in the whole process is only 87.6%, and the pass rate is 95.3%. Edge fractures often occur, resulting in the need to slow down production. At present, the main methods in China are to control the reduction rate of the acid rolling process and strictly prohibit mid-wave, but the effect is not obvious.

Mixed crystals and coarse grains lead to uneven deformation of the edge structure, which is easy to cause local stress concentration

This makes it very easy to generate cracks and extend and spread during cold deformation, resulting in the occurrence of acid rolling edge cracks

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