Study on the roles of bisulfite in the stress corrosion cracking of 7050-T7451 aluminum alloy in the thin electrolyte layer environment
Mingtao Wang, Liwei Wang, Wendi Yang, Yuxi Liu, Herman Terryn, Zhongyu Cui
Abstract
Effect of bisulfite (HSO 3 - ) on the stress corrosion cracking (SCC) behavior of 7050-T7451 aluminum alloy in the thin electrolyte layer environment in the presence of Cl - is investigated. Addition of HSO 3 - inhibits the corrosion initiation but promotes the corrosion propagation and hydrogen uptake. With a quantitative calculation, the HSO 3 - is demonstrated to significantly facilitate the synergistic effect between stress, corrosion, and hydrogen during the in-situ tensile test , resulting in the change of the SCC controlling step from corrosion-induced hydrogen to mechanical-electrochemical-hydrogen interactions. The buffer effect of HSO 3 - plays a dominant role in the HSO 3 - -induced acceleration of the SCC degradation.