Effects of dissolved hydrogen on the crack-initiation and oxidation behavior of nickel-based alloys in high-temperature water

The effects of dissolved-hydrogen concentration on the formation of oxide films on Alloy 182 were investigated, along with the crack-initiation time. Results from both in-situ Raman analyses and ex-situ electron microscopy analyses indicated that NiO formed at lower dissolved-hydrogen concentrations as the NiO Raman peak decreased, whereas Cr2O3 peak and spinel oxide peaks appeared as the dissolved-hydrogen concentration increased. Crack-initiation testing showed that the crack-initiation time decreased as the dissolved-hydrogen concentration increased. The stable and thick NiO could act as a barrier to ion diffusion, and may increase the crack-initiation time of nickel-based alloys.