Fatigue Durability of a Single-Crystal Nickel-Based Superalloy with Prior Corrosion

The impact of hot corrosionHot corrosion on the low-cycle fatigueFatigue (LCF) life of the AM1 Ni-based single-crystal (SX) superalloySuperalloys in as-cast (AC) and fully heat-treated (FHT) states has been studied. Microstructural features such as pores and chemical segregationSegregation have a significant impact on LCF fatigueFatigue strength at 950 °C. Surface pores act as stress concentration zones, influencing crack initiationCrack initiation and propagation. The reduction in the chemical dendritic segregationSegregation through solution heat treatmentSolution heat treatment improves the LCF resistance. Pre-corrosion lowers the LCF lives by increasing stress concentration and facilitating multiple crack initiationsCrack initiation with a brittle, spalled corrosion layer on the surface. The mechanical degradation occurs simultaneously to hot corrosionHot corrosion and oxidationOxidation, the latter being influenced by the distance from the layer undergoing hot corrosionHot corrosion. Heat treatmentHeat treatment still appears to be a positive factor in improving the service life of AM1.