Influence of environmental conditions on localized corrosion of an austenitic stainless steel under cyclic loading

摘要

Austenitic stainless steels tested under cyclic loading in corrosive environments often suffer corrosion fatigue in combination with other kinds of localized damage. The occurring types of corrosion are influenced by both mechanical and (electro-)chemical parameters. The present study investigates the corrosion behaviour of a CrMnNiN austenitic stainless steel under cyclic loading in different media ranging from mild to aggressive by changes in pH-value, chloride content, temperature and mean stress. In order to improve the understanding of the relation between environmental conditions and fatigue limit, the types of damage were detenrrined by fracture surface analysis using scanning electron microscope (SEM). Furthermore cyclic polarization tests were conducted to characterize the electrochemical properties of the steel in each testing solutions. The results show the influence of testing conditions on the occurring types of localized corrosion, such as pitting and stress corrosion cracking, which compete or superimpose corrosion fatigue and lead to reduced fatigue strength.