The effect of porosity size on the high cycle fatigue life of nickel-based single crystal superalloy at 980 °C

• Published in: International journal of fatigue Vol. 147; p. 106191
• Main Authors: Jiang, Wen, Li, Piao, Yao, Wei-Xing, Rui, Shao-Shi, Shi, Hui-Ji, Huang, Jie
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2021
• Subjects: Fatigue crack initiation; Fatigue life evaluation; High cycle fatigue; Nickel-based single crystal superalloy; Porosity defect size; Porosity defect size; Fatigue life evaluation; High cycle fatigue; Fatigue crack initiation; Nickel-based single crystal superalloy
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2021.106191

[Display omitted] •The HCF lives of N-SC superalloys with different porosity sizes are studied.•Fatigue tests are conducted at T=980°C, f=110Hz, R=0.1and σmax=560-760MPa.•The main crack initiates from a large internal pore, the secondary cracks initiate from oxide layer at low stress.•The critical pore size controls the fatigue life under the investigated condition.•A model based on the multiaxial critical plane is used to evaluate the porosity size-dependent life. The high-cycle fatigue (HCF) lives of nickel-based single crystal (N-SC) superalloys with different porosity sizes were investigated at 980°C. The test results show that the failure cracks are prone to initiate from large pores, and the oxide layer can also act as initiation site for secondary cracks when under low stress level. Despite the observation of oxide layer, the pore defect size remains the dominant parameter controlling fatigue life. Therefore, a prediction model based on the critical plane was used to quantitatively evaluate the effect of pure porosity size on the HCF property of N-SC superalloys. The prediction results show that the proposed model is effective and applicable in engineering.