Effect of Atmosphere and Epoxy Resin Coating on Fatigue Strength of Aluminum Alloy

Abstract

It was experimentally confirmed that the fatigue crack propagation rate of steels is promoted by oxygen and/or humidity in air. And the improvement of fatigue strength of welded joints by epoxy-resin coating was attributed to its protective effect against air and humidity. It was also reported in the previous experiment that fatigue strength of 18-8 stainless steel was not improved by the epoxy-resin coating, because fatigue strength of'this steel .was not affected by oxygen and/or humidity at room temperature. The effects of atmospheres and the various coatings on the fatigue strength of aluminum alloy is studied in this. report. The results obtained are as follows.
1) Fatigue strength of Al-4.5% Mg alloy is affected by oxygen and/or humidity in air. Humidity affects more detrimental on the fatigue strength of aluminum alloy than oxygen.
2) The fatigue strength of Al-4.5% Mg alloy can also be improved by epoxy-resin coating. The larger the stress concentration factor and the thicker the coating, the more the coating is effective.