Abstract
This study compares distributions of strain with those of martensitic volume fraction V_α' around fatigue cracks in SUS304 stainless steel. The specimens having random pattern on their surfaces were fatigued at room temperature (297K) in air. The photographs around fatigue crack were taken by advanced CCD cameras during fatigue tests. Distributions of strain around fatigue cracks were calculated by DIC, or digital image correlation method and those of volume fraction V_α' of α' martensitic phase induced around fatigue cracks were measured with ferrite scope. The higher the strain becomes, the more the α' phase was induced by plasticity-induced transformation around fatigue cracks. Distributions of V_α' closely resemble those of strain around fatigue cracks. These results imply that martensitic phase was transformed according to maximum strain value induced by fatigue loading.
