Cyclic material behaviour of a 4% Ni diffusion-alloyed and a 1.5%Mo prealloyed sintered steel

The use of P/M materials is rapidly expanding concentrating more and more on structural parts such as synchronizer hubs. The need for a more reliable design of highly loaded components already in the virtual design step is requested but mostly fails due to the insufficient availability of the characteristic cyclic values for the material. The cyclic material behaviour of components can be estimated for the pre-design stage by the Ramberg-Osgood and Manson-Coffin-Basquin equations which result from strain controlled fatigue tests. For sintered steels a special procedure must be applied for testing as well as for evaluation in order to derive reliable material properties. This paper summarizes the cyclic material properties derived for two different sintered steels, a 4% Ni diffusion-alloyed steel (Distaloy AE) and a 1.5% Mo prealloyed steel (Atomet 4901) admixed with 2% Cu, for two different densities. The testing procedure and the evaluation will be presented and the pr acticability of this method for fatigue design will be discussed.