Abstract
The air pressure dependence of the fatigue life of lead was determined at cycle frequencies of 64 and 500 cycles/min and at total strain amplitudes of ±0·092% and ±0·140%. The effect of changing the frequency and strain amplitude was to shift the air pressure dependence of the fatigue life curve on the life axis but not significantly on the pressure axis. These results are discussed in terms of the sorption of oxygen at the tip of a crack and the supply of oxygen to the tip by either an equilibrium oxygen adsorption model or a kinetic supply model. The results are shown to be consistent with the adsorption model.