Effect of Cooling Rate on Corrosion Properties of High Strength Aluminium Alloys under Atmospheric Conditions.

摘要

Long-term outdoor exposure tests were done to investigate the effect of cooling rate on corrosion and stress corrosion properties of extruded rods of the high strength aluminium alloys 2024-T4, 2023-T6, 7075-T6 and 7075-T73. The 2024 alloy exhibited a high susceptibility to SCC irrespective of best treatment and cooling rate, whereas 7075-T6 was susceptible to SCC only at high cooling rates. All tested alloys showed an abrupt change from low to high SCC growth resistance at specific cooling rates. The 2024 alloy proved to be more prone to exfoliation corrosion than 7075. The corrosion susceptibility decreased at high cooling rates for 2024-T4 and 7075-T6, whereas the cooling rate had no effect for 2024-T6 and 7075-T73. Both the SCC and exfoliation corrosion behavior could be predicted by accelerated laboratory test methods.