Option of HIP Implementation Scheme and Its Effects on the Mechanical Properties of a Nickel-Based Single Crystal Superalloy

The microporesMicropore and residual eutecticResidual eutectic in nickel-based single crystalSingle crystal (SX) superalloysSuperalloys can promote crack initiationCrack initiation in the SX turbine bladesTurbine blades during service, threatening the components’ safety. Hot isostatic pressing (HIPHot Isostatic Pressing (HIP)) treatment is an effective technique to reduce microporesMicropore and enhance the mechanical propertiesMechanical properties of the alloys. This work investigated the effect of two typical HIP implementation schemes on a nickel-based SX superalloySuperalloys compared with a conventional heat treatmentHeat treatment scheme (without HIP). The results show that the HIP-treated samples had fewer microporesMicropore, residual eutecticResidual eutectic and better mechanical propertiesMechanical properties than that of the non-HIP sample. The HIP treatment can increase the yield strength, elongation and reduction in area of tensile propertiesTensile properties at 760 °C compared with the non-HIPHot Isostatic Pressing (HIP) sample, but has no noticeable effect on that at 980 °C. The HIP treatment on the solution-treated sample enhanced the creepCreep rupture life more than that of the as-cast sample at 980 °C/250 MPa, but had no influence on it at 1100 °C/130 MPa. The HIP effect on the fatigueFatigue rupture cycles was closely related to the type of crack initiationCrack initiation site. The HIP treatment significantly prolonged the rupture cycles of low-cycle fatigueFatigue (LCF) at 760 °C and high-cycle fatigueFatigue (HCF) at 850 °C of HIP-treated samples by changing the crack initiationCrack initiation sites, but had no impact on that at 980 °C. Comparing different HIP implementation schemes on microstructuresMicrostructure and comprehensive mechanical propertiesMechanical properties, the HIP treatment on the solution-treated sample was better than that on the as-cast sample. This work can improve the mechanical propertiesMechanical properties and provide guidance for HIPHot Isostatic Pressing (HIP) implementation scheme of nickel-based SX superalloysSuperalloys.