Sheet formability and performance of metastable austenitic stainless steels

The sheet formability of AISI Types 301, 304, and 305 stainless steels, ranked in order of increasing stability to strain-induced martensite formation, was evaluated as a function of temperature between 15 and 60 circle C. Forming limits spanning deep drawing, plane strain, and biaxial stretching strain states were determined by circle grid analysis of sheet specimens subjected to punch-stretch testing at a constant punch displacement rate. Amounts of strain-induced martensite were measured as a function of strain by magnetic measurement. Formability varied widely depending on test temperature and austenite stability, a result of temperature- and strain-dependent formation of martensite that in some conditions was beneficial and in some conditions was detrimental to formability. These results are presented and discussed in detail.