Influence of the individual microstructural features on pitting corrosion in type 304 austenitic stainless steel

摘要

The individual role of microstructural features viz. grain boundary character distribution (GBCD), grain size and residual strain on pitting corrosion is assessed in type 304 stainless steel employing potentiodynamic and potentiostatic polarization tests. Greater fraction of Sigma 3(n) (n <= 3) boundaries and J(3)-type triple junctions have resulted in better pitting resistance in the optimized GBCD specimen. The presence of higher dislocation density in the deformed specimen has resulted in greater pit generation rate. The fine-grained microstructure has exhibited inferior pitting resistance due to its higher random high angle boundary surface area which serve as preferential sites for nucleation and growth of pits.