Effect of Atmosphere on the Fatigue Strength of Mild Steel

Abstract

In order to study the effect of air on the fatigue strength of steel, mild steel plate specimens with and without round or vee shape notch were tested by the laboratory--made fatigue testing machine in the atmosphere controlled tank.
The results obtained are as follows.
1) The fatigue strength of mild steel is decreased by oxygen or water vapour in atmosphere and if both exist in atmosphere, the influence becomes more remarkable. Nitrogen has little effect on it.
2) Fatigue crack initiation and endurance limit of mild steel are little affected by oxygen and water vapour in atmosphere.
3) The effect of atmosphere on the fatigue strength is not affected by the profile of specimen.
4) Oxygen or water vapour accelerates the fatigue crack propagation.