Grain boundary engineering of metastable 204Cu, 301, and 301LN austenitic stainless steels to improve their sensitization resistance

Abstract

Grain boundary engineering (GBE) of 304 and 316 austenitic stainless steels has been widely researched but studies on other grades of austenitic stainless steels are less common. In this study, application of GBE on metastable austenitic stainless steels 204Cu, 301, and 301LN was assessed. Thermomechanical processing parameters were obtained for each of the tested steel grades by varying cold rolling reduction and annealing temperature, and analyzing the acquired grain boundary character distributions (GBCD) in scanning electron microscope (SEM) with electron backscatter diffraction (EBSD). A high fraction of about 80% low-Σ CSL boundaries was attained in all of the tested steels. Effect of the GBE-treatments on sensitization and intergranular corrosion properties was studied with Streicher and DL-EPR tests. GBE-treating was found to beneficially decrease the rate of intergranular corrosion and sensitization in 204Cu and 301 steels, but in low-carbon 301LN steel no improvement was observed.