Corrosion Screening of EV31A Magnesium and Other Magnesium Alloys using Laboratory-Based Accelerated Corrosion and Electro-Chemical Methods

摘要

Test specimens of EV31A and other prospective magnesium alloys for U.S. Department of Defense systems were identically prepared and exposed under bare, uncoated conditions in chamber-based laboratory-accelerated corrosion test methods to assess their relative susceptibilities to general and pitting corrosion attack. The methods used were ASTM B117 neutral salt fog (NSF) and General Motors (GM) Standard 9540P cyclic accelerated corrosion. The NSF specimens were compared at intervals of 18, 72, and 168 h. The GM 9540P specimens were assessed at 1-, 5-, and 10-cycle intervals. The visual corrosion assessments were graphically obtained using flatbed scanning techniques. Following the exposures, mass loss measurements were obtained for all specimens to determine corrosion rates. Electro-chemical evaluations of corrosion susceptibility for each of the alloys were performed using potentiodynamic polarization. Based on the results of these studies, the overall corrosion resistance for EV31A was found to be good, and its relative susceptibility to general corrosion attack compared with the current military specification alloy AZ31B is discussed.