Experimental observation of microstructure evolution under strain-path changes in low-carbon IF steel

The microstructure of a Ti-killed interstitial free OF) steel has been exam ined through TEM observations after simple-shear/simple-shear strain-path c hanges, in connection with the crystallographic orientation of the examined grains. A partial disappearance of prestrain microstructures is shown to c ause the stagnation of work hardening at earlier stages of reversed loading during Bauschinger simple shear sequences. Under progressing reversed defo rmation, 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 wi thin the grains containing well-developed prestrain dislocation boundaries and belonging to certain orientation groups. (C) 2001 Elsevier Science B.V. All rights reserved.