The solution treatment, aging hardening behavior and aging precipitation characteristics for precipitate strengthened austenite superalloy Incoloy 907 have been studied in the present investigation. The result showed that the aging hardening behavior and the relevant mechanical properties relate closely to the microstructure in the alloy. Incoloy 907 is strengthened mainly by γ'-phase with dispersed distribution which has the same structure as the matrix of austenite. Both the shape and size of γ'-phase change obviously in various aging conditions. When the aging temperature is high enough, large amount of needle like ε-phase with an orthogonal structure precipitates in Incology 907. Further discussion on phase precipitation during aging in the alloy has been made in detail. On the basis of studying the microstructure characteristics, the susceptibility of hydrogen embrittlement in Incology 907 under different aging conditions has been studied. The results indicated that a serious internal hydrogen embrittlement (IHE) tendency exists in Incoloy 907. The IHE tendency in creases with increasing aging time and aging temperature. This means that the susceptibility to IHE in Incoloy 907 is affected by the variation of microstructure in the alloy. From the analyses on the results of the tensile properties and the observation of fracture surface, it is suggested that the obstruction of γ'phase to the movement of dislocations carring hydrogen play the most important role in the process of hydrogen embrittlement in the alloy.
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