Influence of iron content on mechanical properties of Al-Mg-Si alloy sheets

摘要

The influence of iron content on mechanical properties of Al-1.0mass percent Si-0.5mass percent Ng-0.1 mass percent Mn alloy T4 sheets was investigated. The amount of Al-Fe-Si second phase particles increased with iron content, thus silicon atoms were consumed by formation of Al-Fe-Si particles. Furthermore, tensile strength of the samples in T4 condition was not influenced by iron content, but the paint bake response decreased over 0.5 mass percent. This was the result of lowering age hardening rate at the early stage of artificial aging because of the loss of silicon atoms. Also, bendability of the samples became worse with iron content. But, it was the worst at 0.5 mass percent of iron content, while it at over 0.5 mass percent became better or the same. The reason was considered as below. Cracking by bending occurred along the second phase particles and the shear bands. And the amount of second phase particles increased with iron content, whereas the formation of shear bands decreased with iron content over 0.5 mass percent because of the loss of silicon. In addition, formability became worse slightly with iron content.