Deformation behavior of ferrite-austenite duplex high nitrogen steel

Abstract

The tensile deformation behavior of ferrite-austenite duplex high nitrogen steel has been investigated by interrupted tensile tests and compared with that of fully austenitic high nitrogen steel. It shows that ferrite is softer than austenite and most of the strain in early and later stages of deformation is accommodated by ferrite, while austenite undergoes a deformation-induced martensitic transformation. Such accommodation of a large amount of strain in ferrite is responsible for rapidly increasing work hardening rate and the resultant higher ultimate tensile strength of duplex high nitrogen steel as compared to those of fully austenitic high nitrogen steel, although duplex steel contains a smaller amount of N than austenitic steel.