Strain-rate sensitivity of hydrogen-assisted damage evolution and failure in dual-phase steel: From vacancy to micrometer-scale void growth

Micro-damage quantification and associated microstructure characterization in a ferrite/martensile dual-phase (DP) steel were performed after tensile tests with different strain rates of 10(-2 )and 10(-4) s(-1) in order to understand the strain rate sensitivity of damage initiation resistance and damage arrestability. The results indicated the following two conclusions: (1) The damage nucleation rate at martensite increases with decreasing strain rate, and (2) lowering strain rate reduced the critical strain for fracture by shortening the damage arrest regime. However, the failure mode was ductile manner at both of the strain rates.