Low-cycle fatigue behavior of a directionally solidified Ni-based superalloy subjected to gas hot corrosion pre-exposure
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The influence of gas high-temperature hot corrosion (HTHC) pre-exposure on low-cycle fatigue (LCF) behavior was characterized for the directionally solidified (DS) Ni-based superalloy DZ125. Fatigue tests were carried out at 850 °C in the pre-exposed and unexposed specimens for 2, 15 and 25 h. Experimental results show that the porous corrosion scale and γ′-depleted layer formed in gas hot corrosion condition alter the crack initiation mechanisms of the superalloy. Fatigue cracks of the pre-exposed specimens originate from multiple surface locations where spalling of the corrosion products occur, while nucleation of unexposed specimen begins in the defects close to the surface. There is a significant reduction in LCF behavior for pre-exposed specimens in comparison with unexposed specimens.
KeywordsLow-cycle fatigue Hot corrosion Pre-exposure Burner rig Ni-based superalloy
This study was financially supported by the National Natural Science Foundation of China (No. 51571010) and the National Basic Research Program of China (No. 2015CB057400).