Improvement of shape memory effect by ausforming in Fe–28Mn–6Si–5Cr alloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2001-09, Vol.315 (1), p.174-179
• Main Authors: Wang, Defa, Liu, Daozhi, Dong, Zhizhong, Liu, Wenxi, Chen, Jinming
• Format: Article
• Language: English
• Subjects: Applied sciences; Ausforming; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deformation and plasticity (including yield, ductility, and superplasticity); Exact sciences and technology; Martensitic transformations; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Shape memory effect; Strength of austenite; Substructure
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(01)00959-5

The influence of ausforming (deformation of austenite above Md, the uppermost temperature for stress-induced martensitic transformation) on the shape memory effect (SME), microstructures and mechanical behavior in Fe–28Mn–6Si–5Cr (wt.%) alloy were systematically studied. It was found that the SME of the alloy Fe–28Mn–6Si–5Cr (wt.%) could be effectively improved by ausforming at 700°C for 9% tensile strain, in the process of which the oriented stacking faults and dislocations were evolved and regularly distributed in austenite. By taking the above-mentioned well-restored substructures as nuclei for γ→ε transformation, the regularly oriented and uniformly distributed ε martensites were stress-induced and were observed with atomic force microscope to be highly reversible. The best SME did not correspond to the lowest proof stress σ 0.2, so the traditional opinion that SME could be guaranteed by strengthening the parent matrix was not confirmed.