Strain-controlled fatigue behavior of cold-drawn type 316 austenitic stainless steel at room temperature

The strain-controlled fatigue behavior of cold-drawn type 316 austenitic stainless steel has been investigated at strain amplitudes varying from 0.22% to 0.75% at room temperature. The results showed that continuous cyclic softening occurs over the whole lifetime at strain amplitude higher than 0.35% in the 20% cold-drawn steel, and 0.31% in the 30% cold-drawn steel, which implies that there is a threshold strain required for cyclic softening during fatigue. The 30% cold-drawn steel displays higher elastic strain amplitudes, resulting in higher fatigue life at strain ranges below 0.80%, while the 20% cold-drawn steel exhibits higher plastic strain amplitudes, leading to higher fatigue resistance at strain ranges above 0.80%. The interactions between dislocations and deformation twins activated during prior cold-drawing process were observed under cycle loading, which play a significant role in the evolution of dislocation structure and subsequently influence the fatigue property.