Corrosion of Linear-Friction-Welded AZ91 and AZX912 Mg-Al Alloys

The corrosion performance of the AZ91 and AZ91 + 2%Ca (AZX912) magnesium alloys joined using linear friction welding was investigated. For similar and dissimilar metal combinations-namely AZ91/AZ91, AZX912/AZX912, and AZ91/AZX912, the performance was evaluated by mass loss analysis and the scanning vibrating electrode technique in 1 wt% NaCl solution. Galvanic behavior between AZ91 and AZX912 was examined by potentiostatic polarization and galvanic current measurements. Approximately 0.3-0.6 mm thick seamless weld zones were generated in all of the welds, which did not show any appreciable changes in the surface profiles acquired after the corrosion test. The corrosion-induced mass loss rate of the AZ91/AZX912 dissimilar weld was 10% higher than those of the AZ91/AZ91 and AZX912/AZX912 similar welds. The galvanic test indicated that AZ91 and AZX912 were the anodic and cathodic regions, respectively, with a difference in the corrosion potential of 20-30 mV. The corrosion of the AZ91/AZX912 weld was presumed to proceed via a macro-galvanic cell between the base alloys, whereas the weld acted as a bridge and did not influence the corrosion.

Automated summary

The corrosion performance of AZ91 and AZ91 + 2%Ca magnesium alloys joined by linear friction welding was investigated. The results showed that the corrosion rate of the dissimilar AZ91/AZX912 weld was higher than that of the similar AZ91/AZ91 and AZX912/AZX912 welds. The galvanic test indicated that AZ91 and AZX912 acted as an anodic and cathodic region respectively, with a difference in the corrosion potential.