Ultrafine grained Fe-Cr-Ni austenitic stainless steels by cold rolling and reversion annealing: A review of progress in Iran

The notable contributions of Iranian scientists in the field of formation and reversion of straininduced martensite for grain refinement and enhanced mechanical properties of Fe-Cr-Ni austenitic stainless steels are reviewed. Accordingly, the processing of ultrafine grained (UFG) structure via cold rolling and reversion annealing is summarized for AISI 301, 304, 309Si, 316, and 321 stainless steels, as well as their variants. The repetitive and innovative thermomechanical processing routes are introduced as well. The understanding of the stages of annealing (reversion of straininduced martensite to austenite, primary recrystallization of the retained austenite, and grain growth) and the underlying reversion mechanisms (diffusional-type and martensitic shear-type) constitute the subsequent part of this overview. Finally, the transformationinduced plasticity (TRIP) effect in the reversiontreated metastable austenitic stainless steels is discussed. The present review paper summarizes these achievements with the discussion on the future prospects in this research field.