Effects of Atmosphere and Epoxy Resin Coating on the Fatigue Strength of Austenitic Stainless Steel

Abstract

It was experimentally confirmed that improvement of fatigue strength of mild and high strength steels by epoxy-resin coating of notched part is attributed to its protective effect against oxygen and/or humidity in air. Fatigue strength improving effect of epoxy-resin coating may be wonder for austenitic stainless steel, because it is considerably stable for oxygen.
Therefore the effects of atmosphere and epoxy-resin coating on the fatigue strength of 18-8 austenitic stainless steel are studied in this report. Plate bending fatigue testing machine is equiped in the atmosphere controlled chamber and rotating bending fatigue testing machine were used for these experiments.
The results obtained are as follows.
1) The S-N curve of 18-8 sautenitic stainless steel in air was almost the nearly that in dry nitrogen. Oxygen content in dry nitrogen and oxygen mixed atmosphere had no influence on a fatigue life of 18-8 austenitic stainless steel.
2) Fatigue crack propagation rate of 18-8 austenitic stainless steel in air was also the same as that in dry nitrogen.
These two points were quite different from the case of mild and high strength steels.
3) Little effect of epoxy-resin coating was recognized on fatigue strength of austenitic stainless steel collared bar specimen.
4) It can be concluded that the fatigue strength of austenitic stainless steel is not affected by oxygen and/or humidity in air at room temperature and little effect of epoxy-resin coating is expected on its fatigue strength.