Abstract
Several plates had been sampled from a large-scale cast aluminum alloy, AC4CH, ingot. Subsequently, rotating bending fatigue tests and microscopic observation had been conducted using three kinds of specimens with different solidification rates. The shape of pores, hardness and dendrite arm spacing (DAS) were affected by the solidification rates, while the fatigue strengths of three specimens were insensitive to the rates. The lower limit of fatigue strengths were estimated by means of extreme value theory. When separately-located pores were dominant in the specimen, the prediction was inconsistent with test results. The modified counting method of pore size was proposed to improve the accuracy of the prediction.
