Stability and Relaxation of Homogeneous Microstresses in Two-Phase Steels with Cyclic Loading

Abstract

The development of residual stresses during cyclic loading was investigated for a duplex stainless steel with nearly balanced portions of ferrite and austenite. The parameters of the study are the predeformation of the material, the loading mode and the loading amplitude. The X-ray stress evaluation distinguishes between macrostress, homogeneous microstresses of the phases as well as orientation dependent microstresses between the crystallites. Pulsating bending was applied to achieve pure tension on one surface of the specimen and compression on the opposite side. The presented investigations prove a remarkable stability of the homogeneous microstresses independent of the height of the stress amplitude even when exceeding the yield strength. In the steel investigated microstresses change only if macroscopic plastic deformation opposite to the predeformation takes place during cyclic loading. That holds as well for orientation dependent microstresses but the latter appear to be more susceptive to change on plastic deformation.