Effective grain size refinement of an Fe-24Ni-0.3C metastable austenitic steel by a modified two-step cold rolling and annealing process utilizing the deformation-induced martensitic transformation and its reverse transformation

Metastable austenitic steels having ultrafine grained (UFG) microstructures can be fabricated by conventional cold rolling and annealing processes utilizing the deformation-induced martensitic transformation during its reverse to austenite upon annealing. However, such are not applicable when has high mechanical stability against transformation, since there is no sufficient amount of martensite formed rolling. In present study, a two-step process was applied an Fe-24Ni-0.3C metastable steel stability. Prior rolling, repetitive subzero treatment were applied. Such dramatically decreased greatly accelerated formation following processes. As result, grain refinement significantly promoted, fully recrystallized specimen with mean size 0.5 ?m successfully fabricated, which exhibited both strength ductility.