Low cycle fatigue properties and life prediction of selective laser melted Inconel 718 at different temperatures
Nan Wang, W.B. Li, C.L. Zou, J.C. Pang, L.J. Chen, Chuanping Gao, Shijian Zheng, Shan Li, H. Zhang, Z.F. Zhang
Abstract
According to the actual service condition of the aeroengine, Inconel 718 produced by selective laser melted (SLM) was selected to perform low cycle fatigue (LCF) tests at 25, 450 and 650 °C, with a focus on the influence of temperature on fatigue properties. The results show that the cyclic stress decreases with the loading except for some cases. Moreover, as the strain amplitude and temperature rise, the degree of cyclic softening increases. Compared with 25 °C and 450 °C, the defects produced by SLM process only have little effect at 650 °C, but the cracks show the characteristics of transgranular fracture at all three temperatures. The deformation mode of SLM Inconel 718 at lower temperature is mainly single-slip, and shows the characteristics of multi-slip deformation with the increase of temperature. After evaluating, predicting and comparing LCF life, the hysteretic energy model related to temperature is proven to an effective approach. Furthermore, the damage mechanisms at 25, 450 and 650 °C can be explained by combining the corresponding parameters, which provides a clue for optimizing fatigue property of SLM Inconel 718.