Application of Martensitic Transformation Fundamentals to Select Appropriate Alloys for Grain Refining Through Martensite Thermomechanical Treatment

The main objective of the current work is to present a predictive model capable of assessing appropriation of a chemical composition for being used in the martensite thermomechanical treatment to develop nano/ultrafine-grained microstructures in austenitic steels. For this purpose, the correlation between stacking fault energy (SFE), driving force for transformation of martensite to austenite, fraction of deformation-induced alpha'-martensite, and saturation strain (epsilon (s)) in some ternary Fe-Cr-Ni alloys and commercial austenitic steels was investigated. It was shown that the volume fraction of alpha'-martensite and epsilon (s) (key parameters in the martensite treatment) are closely related to SFE and the driving force of the alloys. In addition, a nickel-free austenitic alloy was used to evaluate the discussions. A fairly good agreement was found between the calculated and the experimental results.