ABSTRACT
A micro-duplex structure consisting of austenite and ferrite was produced by equal channel angular pressing and subsequent intercritical annealing. As compared to coarse-grained (CG) counterpart, the strength and ductility of micro-duplex samples are enhanced simultaneously due to smaller grain sizes in both phases and more uniformly distributed austenite in ferrite matrix. Many natural and man-made materials consist of dual or multiple phases, which make them exhibit much better strength-ductility synergy than those single phase materials. In current study, the influences of phase boundary on strength and strain hardening rate are investigated. The micro-duplex samples were fabricated by equal channel angular pressing (ECAP) and subsequent inter-critical annealing. Then the strengthening abilities of grain and phase boundaries were quantitatively analyzed. Moreover, the strain gradient theory was used to describe the effect of phase boundary on strain hardening behavior of micro-duplex structure. Micro-duplex structured samples consisting of austenite and ferrite were fabricated by ECAP and subsequent thermal annealing.
