Present level of knowledge on fatigue strength of sintered steels

In general, the development of fatigue loaded PM' parts requires the knowledge of material-related design data like S-N curves, influence of loading mode, notches, mean stress sensitivity on one hand, and on the other hand the knowledge of the service loading and the local stresses resulting in the most critical areas of the part. The comparison between the local and the allowable stresses shows whether the design can be carried out or further optimization is necessary. To reduce the uncertainties resulting from a calculatory estimation and to consider the material- and technology-related scatter bands, fatigue testing is of vital importance. But an optimum design can only be achieved if also the service loading and its scatter are known and if it is related to the design and testing procedure. The knowledge of service lading is therefore a crucial aspect determining the material, the mode of manufacturing and finally the costs.