Fatigue behavior of a sintered steel containing 4% Ni, 1.5% Cu, 0.5% Mo and 0.6% C

Stress controlled fatigue tests were performed on a rather common higher strength PM steel to provide fatigue strength data at 107 cycles accompanied by finite element calculations on the stress concentration factors Kt and the volume V90 exposed to stresses of at least 90 % of the maximum principal stress. Eight different types of specimens were tested under axial, bending and torsion loading. From the nominal fatigue strength at 50 % failure probability A and the stress concentration factor Kt the local fatigue strength KtA was determined and plotted versus the highly loaded volume V90 in double logarithmic co ordinates. A density modified three parameter Weibull distribution is very well suited to describe all re sults at equal stress ratio R, irrespective of loading mode, specimen size or shape and density, over more than five orders of magnitude in V90. These findings suggest a new interpretation of results from notched specimens and permit a universally applicable calculation of component fatigue performance.