ESDU Fat E.05.01 presents three curves of alternating stress against endurance obtained from an analysis of 230 constant amplitude fatigue tests: a mean curve, a curve for an upper limit of fatigue performance where special care is taken in design and manufacture, and a curve for the lower limit where no special attention is paid to design against fatigue. Medium and high strength alloys were used but no correlation was found between endurance and type of alloy. Mean stress varied from 9 000 to 15 000 lbf/sq in (62 to 103 N/sq m).