**1. Introduction**

Al-Mg alloys are non-heat-treatable aluminum alloys, which means they save energy in comparison with heat-treatable aluminum alloys. The Al-Si-Mg alloy, which is a heat-treatable aluminum alloy, is commonly used in automobile manufacture. For example, 6061 is used for forging, 6022 is used for sheet forming, and A357 and Silafont-37™ are used for casting and die casting. When aluminum alloys are used for automobile manufacture, Fe impurities are incorporated into the alloy, which causes AlSiFe intermetallic compounds to solidify when Al-Si-Mg alloys are recycled, reducing the Si content in the Al-Si-Mg alloy as AlSiFe intermetallic compound was crystallized. In Al-Mg-Si alloys, Mg2Si precipitates during aging, causing the strength of the Al-Si-Mg alloy to increase. When the AlSiFe intermetallic compounds solidify, this can cause a shortage of Si for the Mg2Si, and the strength may not increase sufficiently [1, 2]. As a result, Fe impurities have a reduced effect on Al-Mg alloys in comparison with Al-Si-Mg alloys. This is the second advantage of Al-Mg alloys over Al-Si-Mg heat-treatable alloys. Much less work has been done to

investigate the effect of Fe impurities on the mechanical properties of Al-Mg alloys than for of Al-Si-Mg alloys [1–5].

To be suitable for the recycling of aluminum alloys, the selected process must satisfy the following two requirements: saving energy and improving the deterioration of the mechanical properties of the recycled alloy. In this paper, die casting, cast-forging, and roll casting were selected as the processes using the recycled Al-Mg alloys. Die casting can be used to produce aluminum alloy parts in one process with rapid solidification. Cast-forging has the advantage of energy-saving by process saving and the deformation effect, as the casting structure becomes the deformation structure [5, 6]. Roll casting has the advantage of energy-saving by process saving and rapid solidification. The intermetallic composition including Fe impurities becomes fine as a result of the rapid solidification.

In the recycling of aluminum alloys used for automobiles, the Fe content of the aluminum alloy is estimated to increase by 0.2% after shredding [7]. In this study, Fe contents of 0.2%, 0.4%, 0.6% and 0.8% were added to Al-Mg alloys to model recycled Al-Mg alloys. The addition of 0.8% Fe is considered to represent an alloy that has been recycled four times.

The Mg contents of the Al-Mg alloys used in this study were 4.5%, 6%, 8%, and 10%. The Mg content of 4.5% is near that of the 514.0 and 5182 aluminum alloys, and the Mg content of 8% is near that of 518.0. The four Fe contents were added to these four Al-Mg alloys, and test pieces were fabricated with the three selected processes. The mechanical properties were investigated via a tensile test. A deep drawing test was conducted on the plates made from the strips cast by the rolling caster. The suitability of the different Al-Mg alloys for recycling was then evaluated based on the obtained results.
