Variant selection of martensite transformation from ultrafine-grained austenite in Fe-Ni-C alloy

Variant selection rule of martensite transformed from ultrafine-grained austenite was investigated. The specimens were fabricated by severe plastic deformation using accumulative roll bonding (ARB) process with different ARE cycles. The results proved that interaction energy between residual stress in austenite and shape deformation accompanying martensitic transformation determined the variant selection of martensite transformed from the 1-cycle ARB processed specimen having coarse-grained deformed austenite. In contrast, austenite grain shape essentially determined the preferred variants of martensite transformed from the elongated ultrafine-grained austenite fabricated by the 6-cycle ARB process. (C) 2012 Elsevier B.V. All rights reserved.