Laboratory tests have been performed to determine how climatic parameters, e.g., relative humidity, temperature, and the amount of sodium chloride (NaCl), influence the corrosion rate of magnesium alloys AZ91D (UNS M11916) and AM50 (UNS M10500). The effect of the surface state also has been investigated. The exposures were performed at 75%, 85%, and 95% relative humidity (RH) and at 25°C and 35°C. The amount of NaCl ranged from 14 μg cm–2 to 240 μg cm–2. The corrosion rate of both materials increased as a function of temperature, RH, and amount of NaCl. A strong influence of the surface state, i.e., as-cast or polished, was observed mainly due to the combined effect of an active surface layer and the roughness of as-cast surfaces.

Subject
Atmospheric corrosion, Materials, Corrosion rate, Metal surfaces, Profilometry, Magnesium alloys, Sodium chloride, Metal loss, Corrosion products, Mass gain, Salt concentration, Surface layers, Relative humidity
Keywords:
atmospheric corrosion, automobiles, chlorine, climatic parameters, magnesium alloys, relative humidity
NACE International
2004
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