Effect of microstructure on the fatigue behavior of type 304L stainless steel including mean strain and cyclic rate effects

摘要

In this study, the effects of stress and strain rate on cyclic deformation, secondary hardening, martensitic phase transformation, crack initiation, and fatigue behavior of type 304L stainless steel are examined. A series of load and strain controlled uniaxial zero and non-zero mean strain fatigue tests were conducted with varying frequencies in order to investigate the effect of loading rate on fatigue behavior. The volume fraction of martensite was quantified for several tests using x-ray diffraction and electron backscatter diffraction. The loading rates were found to have a direct effect on the microstructure and fatigue behavior of the alloy investigated. Adiabatic heating from an increased rate of loading was found to effect martensite formation which is a major contributor to the secondary hardening phenomena associated with many austenitic stainless steels under cyclic loading. Also affected by the microstructural changes were cyclic deformation, crack initiation, microstructurally small crack growth, and fatigue behavior.