Effect of Cold Working and Annealing on Intergranular Corrosion of Metastable and Stable Austenitic Stainless Steels

Abstract

Intergranular corrosion (IGC) susceptibility to Strauss test of metastable and stable austenitic stainless steels annealed at 500-800°C after solution treatment and cold drawing was investigated.
The annealing temperature for giving peak IGC susceptibility ranged from 650 to 700°C in solution treated specimens and it dropped to lower temperatures, 550-600°C, in slightly and moderately cold drawn ones. With increasing the reduction of cold drawing, the IGC susceptibility became very small for all annealing temperatures tested. The critical reduction of cold drawing beyond which the IGC susceptibility diminished increased with increasing carbon content in steel.
The effects of cold working and annealing on the IGC susceptibility of metastable austenitic stainless steels were very similar to those of stable ones. This suggests that the martensite phase induced by cold working of meastable austenitic stainless steels does not necessarily give an essential effect on the susceptibility to IGC.
On the basis of electron microscopic observation of grain boundary morphologies and precipitated carbides in various specimens, the mechanism of the effect of cold working on the change in IGC susceptibility of these steels was discussed.