Corrosion resistances and passivation of powder metallurgical and conventionally cast 316L and 2205 stainless steels

The corrosion resistances and passivation of austenitic 316L and duplex 2205 powder metallurgical (P/M) steels, produced by gas atomizing and hot isostatic pressing (HIP), have been compared with those of their conventional cast counterparts. P/M 316L steel is shown to have significantly higher pitting corrosion resistance than conventional 316L steel in 0.5 M HCl. This effect is ascribed to the fine grained microstructure of the P/M 316L steel yielding an improved passive layer. The latter hypothesis is supported by photoelectron spectroscopy data demonstrating differences between the thickness and composition of the passive layers for the 316L steels.

► Corrosion of powder metallurgical (P/M) and conventional steels has been compared.
► P/M 316L steel has higher pitting corrosion resistance than conventional 316L steel.
► Differences in the passivation process were found for the steels in 0.5 M HCl.
► The presence of three mixed potentials is explained using the mixed potential theory.
► XPS results show differences in the composition and thickness of the passive films.