The effects of nitrogen content and twin boundaries on the yield strength of various commercial heats of type 316 austenitic stainless steel

Abstract

The applicability of the Pickering and Norström equations for yield strength predictions in austenitic stainless steel has been evaluated for several commercial heats of type 316 austenitic stainless steel. Steel with various nitrogen contents and ultrafine grain structure have been investigated. It is shown that the Norström equation provides a better estimation of the σ 0 and k parameters in the Hall-Petch relationship for various commercial type 316 austenitic steels than the Pickering equation. The effect of the increasing number of coherent twin boundaries on the yield strength in type 316 austenitic steels has also been studied. It is shown that the number of twin boundaries per grain has no effect on 0.2% proof stress. It has also been shown that doping of type 316 steel with 30 ppm of boron increases the k parameter in the Hall-Petch relationship by about 50% in coarse-grained alloys (grain size about 0.2 mm).