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    Closing Commentary—IHE-HEE: Are They the Same?

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    I certainly agree that internal hydrogen embrittlement (IHE) and hydrogen environment embrittlement (HEE) are the same on an atomic scale, HEE being caused by hydrogen absorption. This has been demonstrated by a number of investigators in the case of steels [1–4], we have also seen this for pure nickel and titanium alloys [2]. I wish to point up that the relatively large hydrogen pickups (up to 2.5 ppm) observed after short tests at room temperature are not consistent with room temperature diffusivities and have to be explained by hydrogen being drawn inwards by dislocations [5] generated either at the surface (Fisher's sources) or near the surface (Sumino's sources). Disputation of this point [4] cannot be accepted because these authors failed to consider that the dragging efficiency of a dislocation is strain rate dependent. Direct evidence of the role of dislocations in the transport of hydrogen has been supplied [6].

    Author Information:

    Fidelle, J-P
    CEA, Centre d'Etudes de Bruyères-le-Châtel,

    Committee/Subcommittee: F07.04

    DOI: 10.1520/STP38941S