The influence of solute carbon in cold-rolled steels on shear band formation and recrystallization texture

摘要

Two experiments were conducted to clarify the roles of grain size, solute carbon and strain in determining the recrystallization textures of cold-rolled and annealed steels. In the first experiment, samples of coarsegrained low-carbon (LC) and interstitial-free (IF) steels were cold-rolled to a 75 percent reduction in thickness. One sample from each steel was polished and cold-rolled an additional 5 percent, while the remaining samples were annealed for various times at 650 deg C. In the second experiment, three samples from a commercial LC steel sheet were rolled 70 percent at 300 deg C. Two of the samples were given a further rolling reduction of 5 percent of the original thickness, with one of the samples being given this additional reduction at 300 deg C and the other at room temperature. Goss recrystallization textures are strengthened by coarse initial grain sizes, the presence of solute carbon and rolling at a temperature where dynamic strain ageing occurs, but are weakened by additional rolling beyond a reduction of 70 percent, especially when this extra rolling is conducted at a temperature where dynamic strain ageing does not occur. Characterization of key features of the deformed and re-crystallized steels using optical microscopy, scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD) supports a rationale for these effects based on the repeated activation and deactivation of shear bands and the influence of solute carbon and dynamic strain ageing on the operating life of the bands and the accumulation of strain within them.