Strain aging behavior of austenitic stainless steels containing strain induced martensite

Abstract

Transformation of austenite to martensite during deformation is widely used to strengthen metastable austenitic stainless steel grades. It has been reported that aging of cold worked material can result in further strength increases through the formation of additional martensite. Alternate interpretations of the effects of aging on the strength of stainless steels containing strain induced martensite may also be hypothesized. It is well known that plastically deformed ferritic steels can be strengthened by the diffusion of interstitial solute atoms (carbon and nitrogen) during aging at low temperatures. It is anticipated that plastically deformed metastable austenitic steels containing the body-centered martensite phase may also be strengthened in a similar manner. This assumption appears reasonable as martensitic steels, with low carbon content similar to the austenitic steels of interest, have been shown to exhibit aging effects similar to those observed in low carbon ferritic steels. Thus the purpose of the present study was to evaluate the effects of time and temperature on the stress-strain behavior and strength of cold worked metastable 300 series stainless steels to determine the degree to which observed strength increases might be attributed to strain aging.