Corrosion resistance of magnesium alloy sheet

Conclusions

• 1. Annealed sheets of alloy MA2 have a high resistance to stress corrosion in natural (industrial) atmospheres.

• 2. The resistance to stress corrosion of alloy MA2-1 decreases with increasing Al content.

• 3. The corrosion resistance of MA2 and MA2-1 sheets decreases with increasing stress level. The critical stress for MA2-1 sheets 3 mm thick is not reached at 90 to 50% of the yield stress. For the same material but 1.2 mm thick, a stress of 50% of the yield strength is critical, the alloy being immune to corrosion cracking below this level.

• 4. The resistance to stress corrosion of MA2 and MA2-1 sheets is improved by annealing. It increases with the annealing temperature raised from 150 to 350°C.

• 5. Chromate films produced in baths Nos. 2, 3, and 4 increase the resistance to stress corrosion of alloy MA2 sheets. When the film continuity was broken during specimen preparation, the resistance to corrosion of alloy MA2 decreased but remained higher than that of a specimen without an oxide film.