화학공학소재연구정보센터
Journal of Industrial and Engineering Chemistry, Vol.122, 459-471, June, 2023
The mechanism of inhibitive effect on hydrogen permeation of X70 steel by lanthanum microalloying: Enhanced kinetics of desorption
In this work, electrochemical hydrogen permeation tests were carried out to obtain the steady-state hydrogen permeation current of X70 pipeline steel in acid environment and alkaline electrolyte with applied cathodic overpotentials simulating the service conditions of pipelines. It is shown that La-microalloying can efficiently reduce the steady-state hydrogen permeation current density while maintaining the same mechanical performance. The experimental permeation data were fitted with Iyer-Pickering-Zamanzadeh (IPZ) and surface effect model to analyze the inhibitive mechanism on hydrogen permeation, and the results depicted that La element on the material surface greatly facilitates the desorption process of hydrogen atoms. In addition, the calculated hydrogen diffusion coefficient was found smaller after La microalloyed, which can be ascribed to the larger hydrogen trap density. It is suggested that La-microalloying can mitigate hydrogen damage of X70 pipeline steel in both acidic environment or under cathodic protection.