Low-temperature hot corrosion effects on the low-cycle fatigue lifetime and cracking behaviors of a powder metallurgy Ni-based superalloy

In this paper, low-cycle fatigue (LCF) experiments were conducted to analyze the influence of low-temperature hot corrosion on the LCF behavior of the powder metallurgy Ni-based superalloy FGH96 at 700 °C. The LCF lifetime of the salt-coated samples was drastically lower than that of bare samples. The low-temperature hot corrosion would change the crack initiation mode (from subsurface defects to corrosion pits) and early propagation modes (from transgranular to intergranular). Moreover, the degradation mechanism of hot corrosion in the LCF lifetime was connected with early crack initiation resulting both from the deteriorated surface because of corrosion pits and the accelerated fatigue crack propagation due to weakened grain boundaries.