**3.4 Effect of Fe content on tensile test results for the hot-forged gravity-cast ingot**

The tensile stress, 0.2% proof stress, and elongation of the different Al-Mg alloys are plotted against the added Fe content in **Figures 12**–**14**, respectively. The tensile stress was not influenced by the Fe content, as shown in **Figure 12**. The 0.2% proof stress of the Al-4.5%Mg was almost uniform, and that of other Al-Mg alloys increased gradually with increasing Fe content, as shown in **Figure 13**. The results are shown in **Figures 12** and **13** indicate that increasing the Fe content does not have a negative influence on the tensile stress or the 0.2% proof stress.

At Mg contents of 4.5%, 6%, and 10%, the elongation decreased with increasing Fe content, as shown in **Figure 14**. The elongations of the Al-8%Mg with 0.2% and 0.4%Fe were 27.6% and 24.6%, respectively, and the elongation of the Al-8%Mg without added Fe was 24.0%. When the Fe content was 0.2%,

**Figure 12.** *Tensile stress of the hot-forged gravity-cast Al-Mg alloys plotted against Fe content.*

*Characteristics of Al-Mg Test Pieces with Fe Impurities Fabricated by Die Casting, Roll Casting… DOI: http://dx.doi.org/10.5772/intechopen.100940*

**Figure 13.** *The 0.2% proof stresses of the hot-forged gravity-cast Al-Mg alloys plotted against Fe content.*

**Figure 14.** *Elongation of the hot-forged gravity-cast Al-Mg alloys plotted against Fe content.*

the elongation did not decrease but increased. It is thought that the addition of Fe makes the elongation worse; however, in this case, the elongation increased. This means that when Fe impurities are incorporated during recycling, the elongation increases in comparison with that of the virgin alloy, demonstrating that upgrade recycling occurs. The elongation of the Al-8%Mg with 0.4%Fe was 24.6%, which means the added 0.4% Fe did not influence the elongation. The elongations of the Al-8%Mg with 0.6% and 0.8%Fe were 17.4% and 15.6%, respectively. The elongation of the hot-forged Al-8%Mg was excellent when the added Fe content was 0.8% or less. The elongation of the Al-10%Mg with 0.8%Fe was 9.5%, and that of the other Al-Mg alloys were greater than 9.5%. The hot-forged Al-Mg alloys have good elongation when Fe impurities are incorporated during recycling, with Al-8%Mg being particularly suitable for cast-forging and recycling.
