Microstructure, Phase Transformations, and Mechanical Properties of Shape Memory Fe-Mn-V-C Austenitic Steels

The structure and mechanical properties of new dispersion-hardened Mn-(Cr)-Si-V-C steels with a shape memory effect (SME), which undergo strengthening due to the precipitation of VC carbides in a steel matrix, were analyzed. The stabilizing and the destabilizing carbide aging at different temperatures allows one to control and thus adjust the desired strength characteristics (σ0,2 = 250–880 MPa) and amount of reversible deformation (up to 2.7%). The recovery of the shape of the samples was carried out as a result of both the γ-ε transition in the course of heating after preliminary deformation in the initial austenitic state (i.e., due to the transformation of the γ to the ε phase) and the shear re-twinning of martensite in the martensitic ε phase (i.e., due to the occurrence of transformation of the ε to the twinned εtw phase).