Effects of dislocation-trapped helium on mechanical properties of Fe

Novel Methods for Prevention of Hydrogen Embrittlement in Iron

“…Although the yield point did not appear significantly in the annealed cold-rolled sample after He + and H + implantations, the yield stress also decreased (dark curve); however, it was higher than the yield stress in the annealed cold-rolled sample after H + implantation (green curve). As indicated by Xu et al ., similar to hydrogen, the interstitial helium decreased the yield point in iron 9 . If the decrease in yield stress is due to the former mechanism, the decreased in yield stress in the sample after He + and H + implantations is more pronounced.…”

“…Similar to the analysis of helium diffusion in annealed cold-rolled iron 9 , the hydrogen diffusion behavior was simulated in the present study. In the calculations, the distribution of implanted hydrogen, which had a rectangular shape, was not the same as that shown in Supplementary Fig.…”

“…The hydrogen concentration at both surfaces was always zero. The rate of depth change in the hydrogen concentration can be expressed as 9 …”

“…The yield stress and tensile strength also increased slightly. Unexpectedly, it was reported that helium trapped by the dislocations improves the ductility of iron and nickel 9 – 11 . Although the mechanism for improving the ductility of iron and nickel by helium is still not clear, it is suggested that helium delays the aggregation of vacancies produced during sample tension, resulting in an increase in elongation.…”

“…Recently, it was reported that helium trapped by dislocations in iron and nickel increases the total elongation of these metals 9 – 11 . These experimental results were contrary to expectation.…”