Effect of Sharp Notches on the Fatigue Behaviour of a 4 Ni Diffusion-Alloyed Steel

摘要

The fatigue design of sintered components is mostly based on data of unnotched or in some cases mildly notched specimens. The effect of notches, particularly sharp notches, existing due to geometry or in the parting line of the tool is not well known which implies an increased safety factor for the reliability of the fatigue design.This paper summarizes the influence of notches on the fatigue behavior for the sintered steel Distaloy AE at two different densities. To this end fatigue tests under axial, bending and tor-sional loading with unnotched, mildly and sharply notched specimens manufactured in as sintered surface state up to a notch factor of K_(t,axial) = 4.2 for axial loading were performed. The notch factors were determined by numerical calculation for the different loading modes. All specimens were processed under typical industrial sintering conditions at 1120 °C/20min in 95 % N_2-5 % H_2.The results will be evaluated to indicate the fatigue strength as a function of K_t under consid-eration of density and loading mode and compared with results from the literature.