Abstract
In this study, the fatigue tests were carried out for the cast aluminum alloy. The fatigue property and fatigue crack initiation life of cast aluminum alloy were investigated. As the results of fatigue tests of rotary bending type, the test specimens were fractured over 10^8 cycles in very high cycle area. The fatigue limit did not appear. The crack initiation origins were cast detects at the specimen surface or the specimen sub surface. As the results of the fatigue tests under two-step load variation, in the high stress amplitude area, the fatigue cracks were initiated at the initial stage of the fatigue life of D_1=0.0625〜0.125 in the primary stress damage value. It is found that the cast detect size √<area> on the cross section of the specimen follow Weibull distribution. When the maximum cast detect size is estimated using Gumbel distribution, the estimated maximum cast detect size √<area> agreed well with that measured from the experiment.
