Influence of fatigue damage on ultimate tensile stress of sintered iron

Conventional powder metallurgical techniques have been employed to manufacture two levels of sintered porosities in technically pure iron. The porous iron specimens were cyclically loaded with a number of cycles n lower than their expected life N then quasistatically pulled to failure. The ultimate tensile stress (UTS) values of these damaged specimens have been compared with UTS values of virgin specimens. It has been shown that static resistance (UTS) decreases almost linearly with cumulative damage at repeated loading. The decrease in UTS is greater at higher porosity levels and when a tensile (positive) mean stress is used for the cyclic loading.