On the Reversion of Fe-Ni-Mn Martensitic Alloys

Abstract

The reversion behaviors of the age-hardenable Fe-Ni-Mn alloys have been studied in relation to hardness, electrical resistivity and microstructure in order to solve the age hardening mechanism of these alloys. The results obtained in this study are summarized as follows:
(1) There are three causes for the decrease in hardness caused by heating at the temperatures above the aging temperature in the Fe-Ni-Mn martensitic alloys; overaging, austenite reversion and precipitate reversion.
(2) In the Fe-Ni-Mn alloys, the almost perfect reversion is observed all over the age hardening stages, and this reversion shows that the zones are produced during aging. The reversion shows no effect on the re-age hardening behavior after reversion. The activation energy of reversion is estimated as 90∼120 kcal/mol, much greater than those of age and re-age hardening.
(3) The aged alloy transforms into the γ phase after the zones dissolve into the matrix due to reversion.