Effects of various grain boundary engineering processing on microstructure and corrosion behaviors of 304 stainless steel analyzed with a fractal model

Grain boundary engineering (GBE) is designed for metals to optimize the grain boundary characteristics and improve their resistance to intergranular corrosion (IGC). In this study, the effect of various GBE processing on the fraction of low SCSL grain boundaries and random large-angle grain boundary connectivity in 304 stainless steel was investigated quantitatively with a fractal model. The corrosion weight loss rate, corrosion current density and sensitization degree of samples with various grain boundary characteristics were measured, and these corrosion behaviors were studied in term of the fractal dimension. The results showing the specimen after alternating directions cold rolling plus annealed at 1100 & DEG;C obtained the highest SCSL score that was 67.4%. And the value of fractal dimension for specimen after solid solution annealing, cold rolled 5% or cold rolled 20% reduction plus annealed at 1100 & DEG;C for 5 min in GBE was 1.75, 1.53 and 1.46, respec-tively. An indicator defined by fractal dimension for grain boundary characteristic on corrosion behaviors of 304 stainless steel was verified and clarified, and the mechanisms of GBE to improve corrosion resistance were confirmed with the observation of low-energy grain boundary fragments introduced by annealing twins and triple junctions in grain boundaries.& COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Grain boundary engineering (GBE) is a method to optimize the grain boundary characteristics of metals and improve their resistance to intergranular corrosion (IGC). This study quantitatively investigated the effect of various GBE processing on the fraction of low SCSL grain boundaries and random large-angle grain boundary connectivity in 304 stainless steel. The corrosion behaviors of samples with different grain boundary characteristics were studied in terms of the fractal dimension, and a correlation between the fractal dimension and the corrosion resistance was established.