Corrosion Fatigue of Stainless Steels

Abstract: The aim of this work was to investigate the effect ofchloride-containing environments on corrosion fatigueproperties for different stainless steels grades. The steelsinvestigated ranged from the standard 304 grade to thesuperaustenitic 654SMO and the superduplex SAF2507.The environmental influence on fatigue performance wasmainly evaluated from fatigue crack growth measurements usingcompact tension (CT) specimens. In addition, fatigueperformance in the high cycle regime was studied using spotwelded specimens. Corrosion fatigue tests were performed inaqueous solution of 3% NaCl, and compared to the behaviour inair. Variables, which have been investigated, includetemperature, redox potential and fatigue test frequency. Theenvironmental influence on fatigue performance has also beencompared to localised corrosion properties.Fatigue crack propagation rates were found to be higher in3% NaCl than in air for all stainless steels investigated. Thehighest alloyed austenitic steel, 654SMO, showed leastinfluence of the environment. For duplex stainless steels theenvironment enhanced fatigue crack propagation rate to higherdegree than for austenitic stainless steels. This is explainedby a material-dependent corrosion fatigue mechanism.In the high cycle regime, fatigue properties for spot weldedspecimens were found to be decreased between 30%-40% due to thepresence of 3% NaCl.