Sample Preparation Challenges with Highly Metastable Ferritic-Austenitic Stainless Steels

Abstract

Abstract The effects of different sample preparation techniques on a set of laboratory hot-rolled and thermally cycled ferritic-austenitic stainless steels containing 19 – 20 wt.% Cr have been studied. The differences in chemical composition led to different volume fractions of ferrite and austenite and austenite stabilities, which were characterized using composition-based estimates of Md30 and Ms temperatures. The sample preparation methods were combined mechanical and chemical polishing, electrolytical polishing and ion beam cross section polishing. The ferrite-austenite phase ratio and tendency for phase transformation varied with the chemical composition of the steel. Electropolishing is shown to be the only sample preparation method not to cause martensite formation in samples containing metastable austenite.