Effect of Atmosphere on the Fatigue Strength of High Strength Steels

Abstract

Fatigue tests of 55 kg/mm² high strength steel and weather resistant steel were carried out under various atmospheres in atmosphere-controlled chamber.
The results obtained are as follows;
1) The fatigue strength of high strength steel is decreased by oxygen and humidity in atmosphere. Nitrogen has little effect on it.
The critical oxygen content which affects fatigue life of high strength steel is about 1 % which is the same as that of mild steel
2) Fatigue crack initiation is little affected by oxygen and humidity in atmosphere. But gases accelerate the fatigue crack propagation
3) In comparison with mild steel, fatigue lives of high strength steels are considerably affected by air.