Investigation of the Quality and Corrosion Resistance of Recycled AZ91D Magnesium Ingot

Recycled magnesium ingots were processed by Garfield Alloys Inc. and evaluated for compositional consistency, corrosion resistance and microstructural integrity. Ingots were batch processed from recycled (new) scrap materials. Primary ingots (Dow Chemical Co.) were subjected to a similar evaluation. Chemical analysis was conducted on a spark spectrometer, while corrosion resistance was measured with salt spray testing (ASTM B117). Ingot microstructures were inspected with an emphasis on grain structure and discontinuities. Recycled AZ91D ingots behaved similar to the primary ingots in this test sequence. Spectrographic test results of the ingots were not comparable to the batch analysis; lower levels of aluminum and zinc were indicated. Corrosion rates of the ingots ranged from 0.59 to 1.1 and 0.40 to 0.90 mg/cm²/day for the recycled and primary ingots respectively.