**2.2 Fluidity test**

The effects of the Mg and Fe contents on the fluidity were investigated. The results of the fluidity test are shown in **Figure 2**. The fluidity of the Al-Mg alloy

**Figure 1.** *Test piece for the spiral die for the fluidity test and the tensile test.*

*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 2.** *Fluidity of Al-Mg alloys plotted against Mg content at different added Fe contents.*

decreased with increasing Mg content until 6% Mg and then increased as the Mg content was increased beyond 6%. The fluidity was greatest at an Mg content of 10% and progressively decreased at contents of 4.5%, 8%, and 6%.

The fluidity increased with increasing Fe content, as shown in **Figure 2**. The flow stress at the semisolid condition decreased with increasing Fe content because the primary crystal became smaller and exhibited the mushy condition as the Fe content was increased. It is known that Fe is added to aluminum alloys during die casting to prevent the sticking of the solidification layer to the die. The heat transfer between the solidification layer and the die decreases with increasing Fe content because the contact condition between the solidification layer and the die worsens. As a result, the solidification time decreases and the fluidity increases. The increase of the Fe content during recycling; thus, does not make the fluidity worse but better.

#### **2.3 Effect of Mg content on tensile test results**

**Figure 3** shows the results of the tensile test of the die-cast test pieces plotted against the Mg content. Both the tensile stress and the 0.2% proof stress gradually increased with increasing Mg content. The elongation was maximized at 6% Mg and remarkably decreased with further increases in the Mg content to 8% and 10% Mg. The elongation of the Al-6%Mg was 17.4%, which is excellent. The elongation of the Al-10%Mg was 4.7%, which is better than that of A383, a popular alloy for die casting in Japan. These Al-Mg alloys have 0.2% proof stresses and elongations that are better than those of A383. These results demonstrate that the Mg content should be selected based on the target user. If ductility is important, Al-6%Mg is better, whereas if strength is important, Al-8%Mg or Al-10%Mg is suitable.

#### **2.4 Effect of added Fe content on tensile test results**

The tensile stress, 0.2% proof stress, and elongation of different Al-Mg alloys are plotted against added Fe content in **Figures 4**–**6**, respectively. When Fe was added, the tensile stress of each Al-Mg alloy was the same as or better than that of the corresponding Al-Mg alloy without added Fe. In die casting using recycled

**Figure 3.** *Effect of the Mg content of the Al-Mg alloy on the result of the tensile test of the die-cast test piece.*

**Figure 4.**

*Tensile stress of different die-cast Al-Mg alloys plotted against added Fe content.*

Al-Mg alloys, it was clear that the tensile stress was not degraded by increasing Fe content.

The 0.2% proof stress of the Al-Mg alloys with different added Fe contents is shown in **Figure 5**. The results indicate that the 0.2% proof stress was not significantly affected by the addition of Fe. The 0.2% proof stress of the Al-8%Mg and Al-10%Mg increased with the addition of Fe.

The elongation of the Al-Mg alloys with different added Fe contents is shown in **Figure 6**. The amount of decrease in the elongation with increasing Fe content was dependent on the Mg content of the alloy. The elongation of the Al-4.5%Mg decreased substantially with the addition of 0.2% Fe but changed little with further increases in Fe content up to 0.8%. The elongation of the Al-4.5%Mg with 0.8%Fe was 10.2%. It was clear that the elongation of the Al-4.5%Mg was not greatly influenced by the Fe content for Fe contents above 0.2%. The reduction in the elongation from an Fe content of 0 to 0.2% was smaller at greater Mg contents. The elongation of the Al-6%Mg decreased almost linearly from 17.4–8% as the Fe content increased from 0.2% to 0.8%. At Fe contents of 0.2% and 0.4%, the elongation of the Al-6%Mg was greater than that of the Al-4.5%Mg. The elongations of the Al-8%Mg and the Al-10%Mg gradually decreased with increasing Fe content. The elongations of the Al-4.5%Mg, Al-6%Mg, and Al-8%Mg, each with 0.8%Fe, and the Al-10%Mg with 0.4%Fe were greater than

*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 5.** *The 0.2% proof stress of die-cast Al-Mg alloys plotted against added Fe content.*

**Figure 6.**

*Elongation of die cast Al-Mg alloys plotted against Fe content.*

the elongation of the A383, which is 3.5%. This means that die-cast Al-Mg alloys may be suitable for recycling when die-cast Al-Mg alloys are used for automobile parts.
