Comparison of the lath boundary behavior under cold-rolling between lath martensite in low carbon steel and IF steel

摘要

The microstructural development of cold-rolled lath martensite structure in the interstitial free (IF) steel was previously studied. Boundaries between adjacent laths in a given martensite block partly disappear in the early stage of the deformation (10 percent cold rolling). On the other hand, in low carbon steel, it has been reported that the boundaries remain after 50 percent cold-rolling. Further, the deformation structures of lath martensite include lamellar dislocation cells (LDCs), irregularly bent laths (IBLs) and kinked laths regions (KLs). However, the detail of development of deformation structure in lath martensite has not been understood yet. The aim of this study is to clarify the development of deformation structure in low carbon steel in comparison with that in IF steel. Furthermore, an effect of retained austenite is discussed as one of the important roles in deformation structure.