Defect tolerance and hydrogen susceptibility of the fatigue limit of an additively manufactured Ni-based superalloy 718. (October 2020)

• Record Type: Journal Article
• Authors: Kevinsanny, ; Okazaki, Saburo; Takakuwa, Osamu; Ogawa, Yuhei; Funakoshi, Yusuke; Kawashima, Hideto; Matsuoka, Saburo; Matsunaga, Hisao
• Is Part Of: International journal of fatigue. Volume 139(2020)
• Publication Date: 2020-10
• Subjects: Alloy 718 -- Fatigue -- Additive manufacturing -- Defects -- Hydrogen embrittlement; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2020.105740
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: Fatigue strength properties of an additively-manufactured alloy 718. Competition between defect size and grain size in determining the fatigue limit. Successful evaluation of the defect tolerance as a small crack problem. Experimental finding of the harmlessness of solute hydrogen on the fatigue limit. Abstract: The sensitivity of the fatigue limit of an additively manufactured, Ni-based superalloy 718 sample to surface finishing conditions and solute hydrogen was investigated via a series of tension–compression fatigue tests. The results revealed that neither defects nor hydrogen diminished the fatigue limit of the sample. The high defect tolerance of this material is attributed to a large unit of crack initiation in the coarse grain, which eclipses the detrimental effect of AM-process-induced defects. Also, from the results, it is inferred that hydrogen has little effect on the crack propagation rate and the crack growth threshold of the material.