Microstructure and texture evolution under strain-path changes in low-carbon interstitial-free steel

The transmission electron microscopy (TEM) microstructure of a low-carbon Ti-killed interstitial-free (IF) steel has been examined after simple-shear/simple-shear and uniaxial-tension/simple-shear strain-path changes, in connection with the crystallographic orientation of the grains. The results are discussed in the context of the inter-relation between the microstructure and texture evolutions and their joint influence on the mechanical behavior. A partial disappearance of prestrain microstructures is shown to cause the stagnation of work hardening at earlier stages of reversed loading during Bauschinger simple-shear sequences. Under progressing reversed deformation, a fragmentation of the grains of unstable orientations still slows down the work-hardening rate. A strong localization of plastic flow within microbands following an orthogonal strain-path change is shown to occur within the grains containing well-developed prestrain dislocation boundaries and belonging to certain orientation groups.