G0301501 Effect of grain boundary microstructure on fatigue fracture in SUS430 stainless steel

Abstract

Role of grain boundaries in crack nucleation and crack propagation path in SUS430 stainless steels during high-cycle fatigue was investigated based on the observation results of grain boundary microstructure evaluated by scanning electron microcopy (SEM)/ electron back scattered diffraction (EBSD) analyses, to obtain a clue to grain boundary engineering for improvement of the fatigue property. Fatigue cracks preferentially nucleated along high-energy random boundaries, while the low-angle and low-Σ coincidence site lattice (CSL) boundaries showed the higher resistant to fatigue cracking. Fatigue crack path was affected by local grain boundary character distribution (GBCD). The fatigue crack deflected and branched where the crack tip reached to the low-Σ CSL boundaries.