The porosity distribution of nickel‐base single‐crystal superalloy DD5 and its fatigue life property

Abstract

The porosity of nickel-base single crystals (NBSXs) is still an unavoidable casting problem that has a significant influence on the fatigue life of NBSXs. In order to quantify the porosity effect, a porosity-distribution-related life prediction method is proposed in this paper. The porosity size in a NBSX was measured, and the size distribution was regressed. The results show that the porosity size that is characterized by Feret's diameter follows a modified logarithmic normal distribution. The relation among the applied stress, porosity size, and lifetime is expressed by using the proposed method. The disperse band of S-N curve is investigated based on the probability distribution of the porosity size. The results show that the predicted S-N curve agrees well with the experimental data.