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

Highlights: • Similar and dissimilar DP and CP steels were successfully joined by laser welding. • Martensite content was maximal in the FGHAZ regime for DP-DP and CP-CP joints. • The FGHAZ has the most lattice distortion and dislocation density, irrespective of the joint. • Top-hat pattern microhardness profiles with HAZ softening observed for all the joints. • The high-cycle performance was almost identical for all the similar and dissimilar joints. 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.