Does silicon need to be added to aluminum alloy die casting?
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Does silicon need to be added to aluminum alloy die casting? (https://cliqafriq.com/read-blog/184480_the-influence-of-a-solid-melting-furnace-on-the-die-casting-of-aluminum-alloys.html) 1. Aluminum alloy die casting with silicon can increase fluidity, which is mainly aimed at filling under very low pressure such as gravity casting. In fact, there is not much difference between alloys filled with or without silicon at a filling pressure of more than 1MPa. In today's die casting process, the filling pressure can exceed 100MPa, and the alloy with the worst fluidity has no difficulty of insufficient filling.
2. It can reduce the phase transformation volume shrinkage of "liquid-solid" phase. According to many experiments, aluminum alloy with silicon content of about 20% can achieve almost no change in phase transformation volume. Therefore, if the aluminum piston is used in high-temperature occasions, it will generally be an alloy with high silicon content. Because of the essential characteristics of die casting process, it belongs to high-pressure strong filling casting in one direction and does not have the function of reverse feeding, which is completely different from the process characteristics of reverse feeding and filling in low-pressure casting and gravity casting. It is for this reason that the industry specially prepared the aluminum alloy brand with relatively low phase change shrinkage and the highest silicon content as far as possible, especially for the aluminum alloy die-casting process that can not be fed reversely.
Adding silicon into the alloy has disadvantages, which are accompanied by disadvantages. The cost is that the strength of the alloy is reduced to a great extent, and it is more fragile, and its elongation is also significantly reduced.