The effect of strain ratio on morphology of dislocation in low cycle fatigued SAF 2205 DSS

The effects of strain amplitude and strain ratios in low cycle fatigue (LCF) at 0.25 Hz on the final stable dislocation structure of a failure specimen are investigated in a SAF 2205 duplex stainless steel. The morphology of the fatigued dislocation microstructure in α phase consists of dislocation cell structures and persistent slip bands (PSBs). No dislocation loop patches or labyrinths were observed in the α grains. Instead, persistent slip bands (PSBs) and wormlike PSB loops embedded in a highly dense dislocation matrix were found, and the dislocation density increases with the increase of the strain amplitude and tensile mean strain, which changes the strain ratio. The morphology of fatigued dislocation structure in the γ phase is characterized by the strain-induced martensite.