Study on creep properties of nickel-based superalloy blades based on microstructure characteristics

Creep experiments were performed on miniature K480 nickel-based superalloy specimens at 835 °C and 400 MPa. These specimens were cut from turbine blades processed with different casting processes and pouring temperatures. The microstructure analysis, fracture morphology analysis, and grain size analysis were carried out by scanning electron microscopy (SEM), indicating that the influence of the moulding process and pouring temperature on the microstructure of the alloy is mainly reflected in the difference in the size of crystal grains, grain boundary precipitates and casting defects, which in turn affects the high temperature creep properties of the alloy. Based on crystal plasticity theory, a polycrystalline alloy viscoplastic constitutive equation considering the moulding process and pouring temperature parameters is established, meanwhile, the geometric models of the K480 alloy were established based on the observations of its microscopic structure under SEM. The study revealed the relationship between the casting process of the blade, the microstructure of the material, and the creep property of the specimen. The established plastic constitutive model can predict blade stress rupture life under different casting processes.