Cyclic behavior of a superferritic stainless steel at room and intermediate temperatures

Abstract

This paper studies the fatigue behavior at room and intermediate temperatures of a superferritic stainless steel UNS S 44600 that had received different heat treatments. Thermal treatments at high temperature followed by water quenching produces needle-like Cr2N precipitates that detrimentally affect the fatigue life of superferritic stainless steels. At intermediate temperatures, independent of previous thermal treatments, the occurrence of dynamic strain aging was manifested by a pronounced cyclic hardening rate, inverse dependence of the peak tensile stress with strain rate, a high dislocation density and modified dislocation arrangements. Cycling at intermediate temperature demodulates the spinodal decomposition with a fast velocity, improving the fatigue life of aged samples.