We appreciate the discussion of our paper [1] by Kimura [2], who also provides a useful summary of the extensive work his group has done.
Most of Kimura's remarks [2] are about the behavior of high-purity iron. As was indicated in the first paragraph of our paper [1], we were well aware of the effects of purity, and fully intended our results to be applicable to the lower-purity regime. Therefore, we have no comment to make on most of his remarks, as they do not apply to our results.
We believe, however, that he overstates certain of our conclusions, and we disagree with those overstatements. It is well known (e.g. Refs.
[3] and [4]) that Fe Ti alloys of Ti content similar to the one we used, about 0.17w/o Ti, can be heat-treated to remove all detectable interstitial carbon from solution. The alloy we used was in fact produced by the Bain Laboratory of U.S. Steel and was heat-treated in accord with their experience in assuring removal of carbon [3,4]. The homogeneity and processing of this alloy [3] are considerably improved relative to that reported by Kimura et al. [5]. We chose this material for our experiments to test the behavior of hydrogen when it could not interact with carbon, as in previous work [6].
Kimura speculates on the Bernstein experiments [6] without any evidence as to the hydrogen damage he describes. Our previous work on the role of "damage" in iron alloys, including the role of particles in such damage, shows that although yielding effects due to hydrogen can be irreversible, even at quite low charging fugacity, the work-hardening effects at larger strains are