Corrosion Susceptibilities of Magnesium Alloys AZ91, EZ33 and ZE41.

摘要

An assessment was made of the corrosion susceptibility of cast magnesium alloys AZ91C-T6, EZ33A-T5 and ZE41A-T5. Efforts were made to establish the influence of as-cast and machined surfaces on the corrosion behavior. Cast test panels of AZ91C-T6 alloy were compared with specimens obtained from an AZ91C-T6 helicopter transmission gear housing. The corrosion rates were derived by measuring the hydrogen gas evolved ny specimens immersed in sodium chloride solution. The relative order of corrosion susceptibility for panel specimens was: AZ91C-T6 > EZ33A-T5 > ZE41A-T5. AZ91C-T6 gear housing specimens exhibited the lowest corrosion rates. The lower corrosion behavior of housing material was attributed to its relatively uniform microstructure, compositional homogeneity and low level of porosity. The effect of micropores on corrosion behavior was through to mask the influence attributed to surface condition for the test panels.