Manganese micro-segregation governed austenite re-reversion and its mechanical effects

Abstract

Martensite that is mechanically induced from reverted austenite can be reverted again to austenite upon annealing. Carrying out mechanical tests, electron backscatter diffraction, electron channeling contrast imaging, and energy-dispersive X-ray spectroscopy analyses, we observe that Mn micro-segregation governs this re-reversion process in a martensite-reverted-austenite steel. The annealing treatment cannot fully revert all strain-induced effects in this multi-phase alloy (i.e., ductile damage, grain shape change) and introduces some new changes (e.g. precipitate size in martensite). However, the resulting microstructure exhibits the original mechanical response even after multiple reversions, demonstrating the governing role of the mechanically induced martensitic transformation on strain hardening.