Texture analysis and joint performance of laser-welded similar and dissimilar dual-phase and complex-phase ultra-high-strength steels

Abstract

Microstructural analysis based on texture patterns and an evaluation of high-cycle fatigue performance of laser welded similar and dissimilar ultra-high-strength dual-phase (DP) and complex-phase (CP) steel joints are presented. The microstructure, phase volume fraction, grain boundary orientation, and lattice misorientation distribution of the fusion zone (FZ), fine grain heat affected zone (FGHAZ), and inter-critical HAZ (ICHAZ) are characterized by electron back-scattered diffraction (EBSD). EBSD analysis shows that the FZ of the DP-DP joint consists of martensite and ferrite, whereas the FZs of the CP-CP and DP-CP joints are comprised of martensite, ferrite, and bainite. High-cycle fatigue performances are nearly identical for the similar and dissimilar joints.