Effects of Cu and Ti-precipitates on Recrystallization Texture of Cu-precipitation Hardening Ultra Low Carbon Cold-rolled Steel Sheet

Abstract

The mechanism of improved r-value of continuously annealed steel sheets by high temperature hot-coiling in Cubearing ultra low C interstitial-free (IF) steel has been investigated by using the hot-bands with different morphologies of precipitates obtained by various heat-treatment in the temperature range of 500°C to 800°C. By the ODF analysis of recrystallization texture, it was clarified that the γ-fiber texture (<111>//ND) extremely developed by hot-coiling at the temperature ranging from 700 to 750°C. TEM observations also revealed that the complex-precipitates composed of Ti-carbosulfide and Cu were observed only in the same range of hot-coiling temperature. Improvement of r-value by high temperature hot-coiling is caused by the development of γ-fiber texture by precipitation of Cu combined with coarse Ti-carbosulfides which avoids the detrimental influence of fine pre-precipitation of Cu in matrix.