Formation of core-shell type structure in Duplex Martensitic Steel

Microstructures of both as-quenched and intercritical-annealed medium-Mn steel were investigated by transmission electron microscopy to acquire a better understanding ?–? ?–?? martensitic transformations. The orientation relationships among each phases determined as (1¯10)??//(0001)?,[111]??//[112¯0]? for the case sample, (1¯10)??//(1¯11)?//(0001)?,[111]??//[110]?//[112¯0]? respectively. In addition, presences core-shell type microstructures with gradient Mn concentration confirmed ?–martensite being surrounded retained ?. phase was found dependent on growth reversed ? controlled diffusion during intercritical annealing. It strongly suggested that occurred annealing affected stability, which resulted in formation ?/? microstructures.