ATHERMAL, STRESS AND STRAIN INDUCED TRANSFORMATIONS IN MULTIPHASE STAINLESS STEELS

Abstract
An investigation has been made of athermal, stress and strain induced transformations in multiphase (duplex, triplex and quadruplex) stainless steels with a chemical composition of the type 301, 302 and 304. Special thermomechanical treatments consisting in various sequences of athermal transformations, deformation induced transformations, deformation, tempering and recrystallization were developed. This resulted in multiphase microstructures consisting of composite networks of austenite, ferrite, athermal martensite and stress/strain induced martensite (MFAFM) with high strength and high ductility. The effect of dispersed particles of ferrite, athermal martensite, α/γ interfaces, γ twin and grain boundaries, amount of deformation and deformation temperature on the nucleation, growth, morphology, substructure, strength and ductility of the transformation products are discussed.