Corrosion Fatigue Behavior of FV520B Steel in Aqueous H_2S+Cl~- Environment

In order to investigate the fatigue life of centrifugal compressor impeller, corrosion fatigue tests of FV520B stainless steel in air and aqueous H_2S+Cl~- environment are carried out. The corrosion fatigue failure mechanism of FV520B steel is analyzed combining with the fracture morphology observation and a modified fatigue life prediction model is built. The results demonstrate that corrosion fatigue lives of FV520B steel aqueous H_2S+Cl~- environment are dramatically decreased compare with those in air and decreased further with the increasing of H_2S. Corrosion fatigue damages caused by hydrogen emerge gradually when the applied stress amplitude is relatively low and increased with the decreasing of applied stress amplitude. Microstructure observation revealed that corrosion pits are found on the surface of the specimens and the fatigue cracks are initiated on the surface of the specimens in all corrosion mediums and then propagated. Considering the effect of hydrogen on fatigue behavior of FV520B steel,