Experimental investigation and life prediction of hot corrosion pre-exposure on low-cycle fatigue of a directionally solidified nickel-base superalloy

Low-cycle fatigue tests were conducted on the directionally solidified nickel-base super- alloy DZ125 at 850°C in the unexposed and exposed specimens for 2, 15, 25 and 50h in hot corrosion environment. The pre-exposed specimen exhibited a lower life than unex- posed specimens. Fatigue cracks in the unexposed specimens are initiated from defects near the surface, while the cracks of exposed specimens preferentially occur on the sur- face. Hot corrosion damage in fatigue life was found to be associated with the reduction of the bearing area. A novel life prediction methodology based on continuum damage mechanics was proposed to predict the experimentally observed decrease in low-cycle fa- tigue life with increasing prior exposure time.