Oxygen-induced intergranular fracture of the nickel-base alloy IN718 during mechanical loading at high temperatures

Materials Research

Ulrich Krupp²  William Kane¹  Jeffrey A. Pfaendtner¹  Xinyu Liu¹  Campbell Laird¹  Charles J. Mcmahon Jr.¹ 

[1] ,Universität Siegen Institut für Werkstofftechnik Siegen,Germany

关键词: IN718;    intergranular fracture;    dynamic embrittlement;    grain boundary diffusion;   

DOI  :  10.1590/S1516-14392004000100006

来源: SciELO

【 摘 要 】

There is a transition in the mechanical-failure behavior of nickel-base superalloys from ductile transgranular crack propagation to time-dependent intergranular fracture when the temperature exceeds about 600 °C. This transition is due to oxygen diffusion into the stress field ahead of the crack tip sufficient to cause brittle decohesion of the grain boundaries. Since very high cracking rates were observed during fixed-displacement loading of IN718, it is not very likely that grain boundary oxidation governs the grain-boundary-separation process, as has been proposed in several studies on the fatigue-damage behavior of the nickel-base superalloy IN718. Further studies on bicrystal and thermomechanically processed specimens of IN718 have shown that this kind of brittle fracture, which has been termed "dynamic embrittlement", depends strongly on the structure of the grain boundaries.

【 授权许可】

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