Effect of δ Phase on Hydrogen Embrittlement of Inconel 718 by Notch Tensile Tests

Abstract

Abstract: The effect of δ phase on the hydrogen embrittlement (HE) sensitivity of Inconel 718 was investigated by conducting notch tensile tests. Notch tensile specimens with various precipitation morphologies of δ phase were prepared with different heat treatments, and hydrogen was charged into the tensile specimens before tensile tests via a cathodic charging process. The loss of notch tensile strength (NTS) due to the charged hydrogen was used to evaluate the hydrogen embrittlement sensitivity. The results show that δ phase has deleterious effect on NTSs, and the fracture of hydrogen-charged specimens initiated near the notch surfaces. The loss of NTS caused by precharged hydrogen can be greatly decreased by dissolving δ phase. δ-free Inconel 718 alloy is proposed for the applications in hydrogen environments.

Key words: Superalloy, Hydrogen embrittlement, δ phase, Inconel 718

Liufa LIU, Chen LU, Wenjiang DING, Akio Hirose, Kojiro F.Kobayashi. Effect of δ Phase on Hydrogen Embrittlement of Inconel 718 by Notch Tensile Tests[J]. J Mater Sci Technol, 2005, 21(02): 256-260.

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