Low strain rate deformation behavior of a Cr-Mn austenitic steel at -80oC

Abstract

The deformation behavior of a Cr–Mn austenitic steel during interrupted low strain rate uniaxial tensile testing at 80 C has been studied using X-ray diffraction (XRD), electron backscatter diffraction and transmission electron microscopy. Continuous c !e ! a0 martensite transformation was observed until failure. High dislo-cation densities were estimated in the austenite phase (1015 m2), and for the a0-martensite they were even an order of magnitude higher. Dislocation character analysis indicated that increasing deformation gradually changed the dislocation character in the austenite phase to edge type, whereas the dislocations in a0-martensite were predominantly screw type. XRD analyses also revealed sign-ificant densities of stacking faults and twins in auste-nite, which were also seen by transmission electron micro-scopy. At low strains, the deformation mode in austenite was found to be dislocation glide, with an increasing contribution from twinning, as evidenced by an increasing incidence ofP3 boundaries at high strains. The deformation mode in a0-martensite was dominated by dislocation slip.