The Effect of Sampling position from cast blocks on Fatigue Properties for Spheroidal Graphite Cast Iron

Rotating bending fatigue tests at room temperature were carried out on a ferritic spheroidal cast iron (FDI) and a ferritic/pearlitic spheroidal cast iron (FPDI). Two series of fatigue specimens were machined out from a lower and an upper positions of the cast Y-blocks, which were called "lower specimen" and "upper specimen", respectively. Using these specimens, the fatigue strength and fatigue life distributions were investigated. The major results obtained were as follows. (1) The fatigue strength of lower specimens was higher than that of upper ones for FDI and FPDI. (2) In both materials, the average graphite size of the lower specimens was smaller than that of the upper one. (3) The average graphite size had a main effect on fatigue strength and fatigue life distributions.