The corrosion protection study on inner surface from welding of aluminum alloy 7075-T6 hydrogen storage bottle

This study investigated the resistance effect of Sodium-Silicate solution coated on the welding zone surface on stress corrosion cracking, which was caused by the penetration of storage hydrogen into micro cracks. This phenomenon occasionally occurred while welding the joint with gas tungsten arc welding (GTAW) between the bottle cover and body fabricated using aluminum alloy 7075 (Al-Zn-Mg). The coating effect of Sodium-Silicate was evaluated using four factors, namely, hardening agent, solidification method, coating thickness, and baking temperature. Taguchi analysis was applied to determine the optimal parameters, which were then used to effectively improve the corrosion resistance of the welding zone. The corrosion resistance of the group added with magnesium oxide as a hardening agent increased to 200% compared with the group added with Sodium-Silicate but without hardening agent. The penetration depth of the tested group added with talc as a hardening agent also increased to 20%.