Formation of Microstructure and Texture in Intercritically Rolled C-Mn Steel

Abstract

Series of trials were conducted on a laboratory rolling mill to evaluate the influence of intercritical rolling on the microstructure and texture of steel with 0.082%C, 1.54% Mn, 0.35% Si, 0.055%Nb and 0.078%V. Two parallel rolling schedules A and B were designed on the base of the experimentally deduced CCT diagram of the steel. In rolling schedule A the material was subjected to accelerated cooling and coiling simulation after final rolling in the intercritical region, whereas in rolling schedule B the last rolling pass in the intercritical region was replaced by a water quench at the same temperature of the intercritical rolling pass in schedule A. Microstructure and texture were characterized by means of light optical microscopy, scanning electron microscopy, EBSD and XRD. It was found that the average grain diameter and the texture depend significantly on the final rolling temperature in the intercritical region. The decrease of the intercritical rolling temperature leads to an increase of the {111}〈uvw〉 /{001}〈uvw〉 ratio, but at the same time the increase of the average ferrite grain size was also observed. A phenomenological model based on the K–S orientation relationships was used to predict the texture formation in the intercritical region.