Microtexture, grain boundary character distribution and secondary working embrittlement of high strength IF steels

The batch annealing (BA) and continuous annealing (CA) of high strength interstitial-free (IF) steel sheets have been simulated. Micro-texture, grain boundary character distribution (GBCD) and secondary working embrittlement (SWE) were investigated using an electron backscatter diffraction (EBSD) technique. The results show that a crack from SWE occurs preferentially at random boundaries, that low-angle and low-Sigma CSL boundaries can offer resistance to the propagation of SWE cracks. It is suggested that an optimum GBCD described as a high frequency of low-angle or low-Sigma CSL boundaries and a more discontinuous random boundary network in the microstructure of IF steels can offer the potential for decreasing their ductile-to-brittle transition temperature (DBTT), i.e. reducing their susceptibility to SWE. (C) 2004 Elsevier B.V. All rights reserved.