Lamella Multiple Grained Structure Making 2205 Duplex Stainless Steel with Superior Strength and Ductility

Abstract

We demonstrate a 2205 duplex stainless steel (DSS) synthesized by aluminothermic reaction and followed two-step rolling which had a superior yield strength of 863 MPa, ultimate tensile strength of 1 103 MPa and an elongation of 21% at room temperature. The phase, grain size and distribution of the steel were characterized by optical microscope, X-ray diffraction, electron back-scatter diffraction and transmission electron microscope. The results show that the steel consists of lamellar ferrite and austenitic phase with multiple grain size distribution from nanoscale to microscale. The high strength is attributed to strengthening of high back stress arising from laminated dual-phase heterogeneous ultrafine grained structure and distribution. The high ductility originates from back-stress hardening and dislocation hardening.

Keywords

2205 duplex stainless steel / back stress / strength / ductility