NODULAR CAST IRON FATIGUE LIFETIME IN CYCLIC PLANE BENDING

The fatigue behavior of a component is strongly dependent also on the material and its surface condition. Therefore, the manner in which the surface is prepared during component manufacturing (surface roughness, residual stresses etc.) has a decisive role in dictating the initiation time for fatigue cracks. The fatigue behavior of the same material, a nodular cast iron, with three different surface conditions (fine ground, sand blasted and as-cast) has been investigated under cyclic plane bending. The results show differences in fatigue strength, which are associated with the surface conditions. The characteristics of the surface layers of the different test specimens were examined by metallography.