The influence of metallurgical factors on corrosion fatigue strength of stainless steels

Corrosion fatigue strength of stainless steels is controlled by tangled interaction among environmental, mechanical and metallurgical factors. In order to estimate corrosion fatigue strength it is indispensable to understand the role of an each influencing factor. The aim of this paper is to present briefly surveyed results on metallurgical factors on corrosion fatigue strength of stainless steels such as austenitic, martensitic and duplex stainless steels mainly based upon author’s experimental results. The targeted dominant metallurgical factors focussed upon are chemical compositions, heat treatment, manufacturing process and microstructures.The emphasis is placed upon effect of Molybdenum content on corrosion fatigue strength of austenitic stainless steels in 3%NaCl aqueous solution, tempering temperature on corrosion fatigue strength of 13% Chromium stainless steel in 3%NaCl aqueous solution and volume percent ferrite on corrosion fatigue strength of duplex stainless steel in potassium alum aqueous solution. The surface and fracture surface observation by optical and scanning electron microscopy revealed that corrosion pit formed at corrosion fatigue crack initiation area. In light of relatively smaller effect of corrosive environment on corrosion fatigue crack propagation rate it can be surmised that corrosion fatigue strength of stainless steels is governed by crack initiation process. It can be concluded that corrosion fatigue strength of stainless steels is strongly influenced by metallurgical factors such as chemical compositions, heat treatment, manufacturing process and microstructures.The information obtained in this survey directly lead to prevention of corrosion fatigue failure in stainless steels made components, selection of stainless steels in corrosive environments and development of corrosion resistant stainless steels.