Cyclic deformation of ferritic stainless steel single crystals showing the stress asymmetry

Fe–20%Cr and Fe–30%Cr alloys single crystals having (1̄2̄3) maximum resolved shear stressed (mrss) plane were cyclically deformed under constant plastic strain amplitudes εpl of 2.5×10−3 and 1.5×10−4. It was found that the tensile stress amplitude was larger than the stress amplitude in compression at the beginning of cyclic deformation. The stress asymmetry was large at higher cyclic frequency and at higher plastic strain amplitude. During cyclic deformation, the stress asymmetry gradually decreased with increasing number of cycles, especially at εpl=2.5×10−3. The changes in internal dislocation process are discussed based on a model that attributes the stress asymmetry to the asymmetric behavior of the screw dislocation.