Influence of Intra-granular Ferrite on the Tensile Behavior of Intercritically Annealed 12 pct Mn TWIP plus TRIP Steel

Abstract

The influence of intra-granular ferrite islands, fully embedded in austenite matrix grains, on the tensile behavior of intercritically annealed Fe-12 pct Mn-0.3 pctC-3 pctAl TWIP+TRIP steel was investigated. The presence of intra-granular ferrite, which nucleated at twin boundaries during annealing, resulted in an increased yield strength by the Orowan dislocation looping mechanism and the generation of geometrically necessary dislocations at the ferrite particle/austenite matrix interface. The intra-granular ferrite also induced the formation of secondary twin variants. The resulting twin-twin intersections nucleated additional alpha'-martensite, thereby leading to an enhanced TRIP effect. (C) The Minerals, Metals & Materials Society and ASM International 2014