Sintered and porous PM steels are assumed as brittle. That assumption leads to the mechanical idealization of a purely elastic material. The advantage of that assumption is the simple material law characterization only by the density dependent Young’s modulus. Since the German FKM-guideline requires the static strength assessment before the fatigue strength assessment, it is of critical interest to discuss the consequences of that assumption in detail. Own experiments have shown that the effect of notches is overestimated due to local plastic yielding. The introduction of an elastic-plastic material law results in a much better agreement. Due to the continuous hardening behavior of PM steels and the neglectable softening in the stress-strain curve, an approximation with the Ramberg-Osgood power-law is recommended. That power-law exhibits some interesting details. It can be integrated easily to apply Glinka’s or Neuber’s notch root correction and it can be written density dependent for FEA-calculations.
Modelling and Sintering of PM Steels