Acta Metallurgica Sinica (English Letters) ›› 2020, Vol. 33 ›› Issue (4): 514-527.DOI: 10.1007/s40195-019-00986-0

• Orginal Article • Previous Articles     Next Articles

Experimental Investigation on the LCF Behavior Affected by Manufacturing Defects and Creep Damage of One Selective Laser Melting Nickel-Based Superalloy at 815 °C

Xiao-An Hu1,2, Gao-Le Zhao1,2, Yun Jiang1,2, Xian-Feng Ma3, Fen-Cheng Liu4, Jia Huang5(), Cheng-Li Dong6   

  1. 1 School of Aircraft Engineering, Nanchang Hangkong University, Nanchang 330063, China
    2 Jiangxi Key Laboratory of Micro Aeroengine Technology, Nanchang, 330063, China
    3 Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Zhuhai, 519082, China
    4 National Defence Key Discipline Laboratory of Light Alloy Processing Science and Technology, Nanchang, 330063, China
    5 School of Aeronautics and Astronautics, Central South University, Changsha, 410083, China
    6 Materials Evaluation Center for Aeronautical and Aeroengine Application, AECC Beijing Institute of Aeronautical Materials, Beijing, 100095, China
  • Received:2019-09-11 Revised:2019-10-22 Online:2020-04-10 Published:2020-04-15
  • Contact: Jia Huang


Uniaxial tensile tests and stress-controlled low-cycle fatigue (LCF) and creep-fatigue interaction (CFI) tests of Inconel 625 alloy manufactured by selective laser melting (SLM) were performed at 815 °C in air environments. The microstructure was characterized by optical microscopy and scanning electron microscopy after testing. The results confirmed that significant embrittlement and large scatter in LCF life are resulted from manufacturing defects. The CFI life is decreased sharply to approximately dozens of cycles with the accumulated creep strain; however, the selected dwell time (i.e., 60 s and 300 s) exhibits low sensitivity to the fracture time and elongation to failure. The embrittlement of SLM Inconel 625 was proposed to be due to the low grain uniformity and precipitation of carbides at the grain boundaries. Due to the quality of the SLM process, the accelerated initiation and propagation of fatigue crack are caused by the present unmelted powder particles, which result in the large dispersion of LCF life. Meanwhile, due to the accumulation of creep damage, cracks in the CFI test are initiated along the grain boundaries and then linked together, contributing to a significant decline in fatigue life.

Key words: Selective laser melting, Low-cycle fatigue, Creep-fatigue interaction, Failure analysis