Effect of Cooling Mode on the Microstructure of High-Strength Steel during Hot Rolling

Abstract

This paper studies the effect of extreme cooling and traditional cooling on the microstructure of high-strength steel during hot rolling by adjusting the cooling process, combining the theoretical calculation and the thermal simulation experiment, and using metallographic microscope, scanning electron microscope (SEM), and electron backscattered diffraction (EBSD) analysis methods in order to solve the problem of coil collapse in the production process of high-strength steel. The research results show that compared with the traditional cooling method, the front-section fast cooling mode can rapidly cool the hot-rolled sheet to the “nose tip” temperature of the ferrite transformation of the time-temperature-phase-transition (TTT) curve, which can promote the transformation of the material to ferrite, increase the proportion of ferrite, and make the grain size of the organization finer. It helps to improve the overall mechanical properties of the material and reduce coil collapse defects. The front-section fast cooling mode achieves good results in industrial application, the proportion of coil collapse reduces from 9.363% to 0.533%, and the problem of coil collapse is significantly improved.

Keywords

• high-strength steel
• cooling process
• microstructure
• coil collapse