Effect of C, Si and P on Intergranular Corrosion Susceptibility of Type 316 Stainless Steel

Abstract

The effect of C, Si and P on intergranular corrosion (IGC) susceptibility of Type 316 stainless steels (SS) has been studied in terms of the composition dependent IGC and the compound dependent IGC. The results obtained are as follows; (1) C increases the IGC resistance of Type 316 SS in Huey and Coriou tests by supressing the precipitation of Laves phase. However, severe IGC occures in HNO₃+HF and Huey tests when the Cr depleted zone is continuously formed at grainboundaries (GB). (2) Si raises the IGC susceptibility both in Huey and Coriou tests. It is considered that Si enhances the precipitation of Laves phase at GB. (3) P also increases the IGC susceptibility both in Huey and Coriou tests by precipitating as Ni-P phosphides at GB.