EBSD characterization of deformed lath martensite in if steel

Abstract

Rolling deformation results in the transformation of a lath martensite structure to a lamellar structure characteristic to that of IF steel cold-rolled to medium and high strains. The structural transition takes place from low to medium strain, and electron backscatter diffraction analysis shows that the frequency of medium angle boundaries with misorientation angles of 5-10° decreases with increasing strain, while the frequencies of boundaries with angles in the ranges of 1-5° and 10-25° increase, resulting in the evolution of a bimodal misorientation angle distribution. The microstructural evolution and the strength are characterized for lath martensite rolled to a thickness reduction of 30%, showing that large changes in the misorientation take place, while the strain hardening rate is low.