Abstract
The presented study is focused on experimental results of high-cycle fatigue life of a cast polycrystalline nickel-based superalloy IN 738LC at temperatures of 800, 900, and 950°C. The absence of hot isostatic pressing (HIP) led to the occurrence of casting defects in the microstructure. The fatigue tests were performed in symmetrical loading in laboratory air. The fracture surfaces of specimens were studied by scanning electron microscopy to describe the influence of temperature on the fatigue damage mechanism and fatigue crack initiation. Change in the primary crack propagation mechanism from crystalline (stage I regime) to non-crystalline (stage II regime) mechanism was observed with increasing temperature. However, the effect of changing mechanism caused by temperature dependence was unfavorably influenced by casting defects.
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