Investigation of mechanical properties of secondary AlSi7Mg0.3 cast alloys before and after corrosion

Abstract

The casting industry currently use about 35% of secondary (recycled) aluminum and about 65% of primary aluminum to meet their needs. The manufacturer wants to use the secondary aluminum alloys more and more, but these materials have the higher amount of the undesirable elements. The most negative element in such alloys is Fe. Although the corrosion current increased due to the presence of alloying elements in the matrix of aluminum alloys, the higher content of Fe (which led to increasing amount of Fe-rich phases) could affect the corrosion resistance. The basic metallography assessment of experimental materials microstructure confirm the higher amount of Fe-rich phases in secondary alloys. The results of mechanical properties shows that the higher content of Fe (also Fe-rich phases) does not lead to decreasing the mechanical properties. The similar results of mechanical properties were reached after corrosion attack with 3.5 wt. % NaCl. The assessment of corrosion attack confirmed the presence of pitting corrosion on experimental samples, which increase with increasing Fe content.