Effect of Surface Roughness on Hydrogen-Induced Blister Behavior in Pure Iron
Xinfeng Li, Yao Wang, Weihong Huang, Jin Zhang, Xubin Wu
Abstract
The effect of surface roughness on hydrogen-induced blister behavior in pure iron was explored using optical microscopy and microcomputerized tomography. Hydrogen was introduced into the samples by electrochemical precharging methods with various hydrogen charging times. It is found that grinded surface exhibits higher roughness and compressive residual stress compared to those of polished surface. With increasing hydrogen charging time, hydrogen-induced blister height, blister width and blister area fraction increase, regardless of the grinded surface and polished surface. Further, hydrogen blister height and width of grinded surface are comparative to polished surface under the same hydrogen charging time. However, the blister area fraction and the number of blister on polished surface are considerably higher than the grinded surface, indicating that polished surface is more susceptible to the formation of blisters than that of grinded surface, both of surface and interior of the samples. This is dominantly rationalized in terms of the suppression effect of hydrogen invasion in grinded surfaces due to their higher residual compressive stress and higher dislocation density.