Analysis of Microstructure and Textures on Batch Annealed IF Steel with Different Cold Reduction Ratio

Abstract

Based on the experimental materials of hot rolled Ti+Nb-IF steels and Ti-IF steels produced in the industry, the effects of cold reduction ratios on its microstructures, mechanical properties and textures were investigated. The results show that experimental samples with different cold reduction ratios have been finished recrystallization by batch annealing at 720°C and soaking with 5h. As the cold reduction ratio increases, the grains will be refined and uniform, and the textures trends to be {111} texture. The {223}<110>, {111}, and {114}<110> textures appeared after cold rolling are inherited followed by annealing, whose intensities would be higher as the cold rolling ratio increased. And the textures will transform to the {223}<110>, {111}<110> and {114}<110> textures. With the increasing cold reduction ratio, the values of the yield strength Rp0.2 and tension strength Rm increase, but the Rp0.2 is almost about 100MPa. However, the strain hardening index n90 gradually decreases. The plastic strain ratio r90 which reaches the maximum with cold reduction ratio of 70% increases firstly and then decreases. Thus, the optimal cold reduction ratio of 70% to 80% is determined, which can obtain good deep drawing performances.