Martensitic Transformation and Plastic Deformation in 18-14 Stainless Steel Single Crystals

Abstract

Relations between martensitic transformation and plastic deformation have been studied using single crystals of 18%Cr-14%Ni austenitic stainless steel. The Ms temperature for γ→α transformation decreases with plastic deformation due to slip. It has been found that the morphology and the crystal orientation relationships between the martensites and γ have close relations to the slip systems which have been active during plastic deformation. When the martensitic transformation occurs during plastic deformation, the plastic deformation is concentrated in bands parallel to {111} planes of γ and the negative temperature dependence of the yield stress is noted. This is associated with the γ→ε transformation. The above plastic bands are parallel to the most stressed {111} <211> shear system of γ to induce the γ→ε lattice change. The occurrence of the γ→χ transformation results in a decrease in the easy glide strain and in a high strain hardening in the stage II deformation.