In situ monitoring of isothermal phase transformation in two Nb stabilized austenitic stainless steels (316Nb) by neutron diffraction

摘要

In this study, neutron diffraction measurements have been performed to study the phase transformations taking place during isothermal treatments of two 316Nb type austenitic stainless steels with different delta ferrite content. Kinetics of phase transformations during heating, isothermal hold at 900 degrees C and cooling have been monitored and the phase fractions quantified using Rietveld refinements. Two main transformation mechanisms are evidenced and quantified: the delta ferrite transformation into sigma phase and austenite and the sigma phase precipitation inside the austenitic matrix.