A microstructural investigation on deformation mechanisms of Fe–18Cr–12Mn–0.05C metastable austenitic steels containing different amounts of nitrogen

Abstract

Deformation mechanisms of the Ni-free Fe-18Cr-12Mn-0.05C (wt%) austenitic steels containing 0, 0.25 and 0.44 N were investigated. Effects of N addition, strain and temperature on the formation of deformation-induced epsilon- and alpha'-martensite phases were determined using transmission electron microscopy and electron back-scattered diffraction techniques. Based on the microstructural evolutions, it is proposed that deformation mechanism of these steels includes the sequence of gamma -> epsilon-martensite -> alpha'-martensite, in which the formation and stability of the epsilon-martensite is significantly enhanced by the N content. Increased deformation temperature from 298 to 373 K reduces the formation of epsilon-martensite (more than 80%).