Asynchronous effect of N+Cr alloying on the monotonic and cyclic deformation behaviors of Hadfield steel

Abstract

Alloying treatment has always been an effective way to improve the mechanical performance of Hadfield steel. In the present study, Hadfield steel was alloyed with N + Cr, named Mn12CrN steel. Its monotonic and cyclic deformation behaviors were comparatively studied with traditional Hadfield steel, named Mn12 steel. Results showed that the stress responses during monotonic and cyclic deformations were different for these two steels, presenting an asynchronous effect of N + Cr alloying. During monotonic deformation, high-density deformation twins were formed in the Mn12CrN steel at large strain. Together with the solid solution strengthening effect, the Mn12CrN steel obtained higher yield and tensile strengths than the Mn12 steel. However, the maximum cyclic peak stress of the Mn12CrN steel was lower than that of the Mn12 steel during cyclic deformation, though a higher initial cyclic peak stress was obtained in the Mn12CrN steel. The cyclic deformation strain was much smaller than the monotonic deformation. In the strain range of cyclic deformation, planar dislocation configuration was mainly formed in the Mn12CrN steel at the total strain amplitude of 0.4 × 10−2–0.6 × 10−2. While deformation twins and mixed dislocation configurations were observed in the Mn12CrN steel when the total strain amplitude was above 0.8 × 10−2. With these microstructure evolutions in the Mn12CrN steel, low maximum cyclic peak stress but prolonged fatigue life was obtained compared with the Mn12 steel.