Mössbauer study of deformation induced martensitic phase transformation in duplex steel

Samples of cold rolled UR45N austenitic-ferritic duplex steel with cold rolling reduction ranging from 0% to 80% were investigated in the form of foils and powders by means of Mössbauer transmission spectroscopy. It was found that cold rolling has a minor effect on the martensitic transformation even at high reductions in the material under investigation. On the other hand, powdering process induces strong martensitic phase transformation, i.e., about 25% of austenite transforms into martensite during powdering. High rolling reductions as well as powdering reduce an average hyperfine magnetic field at iron by about 1 T, while annealing at about 430°C increases this field by about 3 T.