Fatigue life prediction of sintered steels

Low cycle fatigue damage of a sintered alloy was studied by comparing experimental results with those obtained from a model suggested in the literature, which considers the effect of non-zero mean strain on life prediction. Specimens of sintered Fe-C-Cu alloy with two different porosities were used. Experimental tests were carried out on a servohydraulic machine and the specimens were subjected to partially random loads with a maximum tensile stress equal to 80% of monotonic yield stress for each porosity. For a correct translation of the load sequence into damaging events, cycle counting was performed using the rain flow method and appropriate correlations between cyclic stress and cyclic deformation values were made. Both stress and strain controlled experiments were carried out in order to determine all the required model parameters. The fatigue life obtained experimentally was smaller than that predicted by the model and this difference increased with increasing porosity.