
Using Aluminum Alloy Casting is one of the best ways to achieve a strong and durable product. This material is also very affordable, making it an excellent choice for many projects. Whether you want to make a simple phone case or a more complex piece of machinery, using an aluminum alloy cast part is the perfect way to get the job done.
Microstructure
The as-cast microstructure consists of a minor set of bright precipitates and a set of coarse Al(Zn) dendrites. The eutectic region contains Si-rich particles that have precipitated in the dendrites of the Al(Zn) matrix. The dark semi-circular feature is a defect that results from shrinkage during solidification.
The simulated results were in agreement with the experimental results. The alloys exhibited good microhardness performance. They showed microhardness values two to three times higher than commercial alloys.
The alloys showed good compressive strength up to 644 MPa. However, some alloys showed poor ductility.
Mechanical properties
During the casting process, various parameters such as temperature, squeeze pressure, and die preheating temperature influence the mechanical properties of aluminum alloy casting. In this study, the mechanical properties of aluminum alloy casting was assessed using a feed forward back propagation ANN model. The ANN model was developed with various architectures and was able to simulate the mechanical properties of aluminum alloy casting with reasonable accuracy.
The study included a quantitative metallographic analysis that showed the reduction in microporosity of castings with squeeze pressure. The main effects plot showed the effect of each process parameter. The highest mechanical properties were recorded at the die preheating temperature of 225 degC.
The best way to evaluate the mechanical properties of aluminum alloy casting is to understand the effects of each process parameter. The mechanical properties of aluminum alloy casting are influenced by the process parameters such as the squeeze pressure, die preheating temperature, and melt temperature. The properties of aluminum alloy casting are also affected by the alloy.
Pouring speed range
Optimal pouring speed range for aluminum alloy castings is between 700 degC and 750 degC. Higher pouring temperatures can cause excessive oxide formation, cavities, thermal cracks, and porosity. In addition, high temperatures can trap gas in the castings. High pouring temperatures also result in a coarse-grain metal structure.
A heat-flow simulation model was established to investigate the effect of centrifugal casting process parameters on the solidification behavior of 2060 Al-Li alloy. Different groups of process parameters were compared with 900 r/min rotational speed.
The results showed that the strength increment of alloy increased by more than 100 MPa at rotational speed up to 1000 r/min. In addition, higher rotational speed promoted melt flow and increased the melting velocity field. Increased Reynolds number also improves the filling capacity.
Pouring temperature
Among the many parameters affecting the quality of aluminum alloy casting, the pouring temperature is one of the most critical. It determines the mechanical properties of the alloy, as well as the final casting part quality.
For optimum casting properties, the aluminum alloy must be poured at a temperature at least 200degF above the melting point. In the case of thin-walled casting parts, the pouring temperature should be lower.
However, pouring temperatures that are too high can produce side wall cracks. These cracks can be red or golden, and are likely to leak when pressure is applied. Besides the possibility of side wall cracks, a casting that is poured too hot can cause a number of other problems.
The recommended temperature ranges for different types of aluminum alloy castings are presented in the Aluminum Association System table.
Inclusions
During the melting process, aluminum alloys form inclusions. These particles are difficult to remove from the molten alloy. Moreover, they can cause a poor surface finish. The particles can be either liquid or particle-form.
The extent of inclusions in molten aluminum alloys is dependent on the application. In the case of commercial castings, they are considered to be a detractor of quality. Therefore, it is essential to remove these particles from the molten metal stream.
Various techniques are employed to remove inclusions from the molten metal. They include filtration, fluxing and flotation. Among these, flotation has been widely adopted.
The inclusions are generally classified into two categories: insitu and exogenous. Exogenous inclusions are imported to the molten metal stream from external sources. Exogenous inclusions can be major alloying elements or containment refractory materials.