Features of die-cast aluminum alloy

Die-cast aluminum alloy, cast aluminum alloy and die-casting parts generally contain high silicon content.  The anodic oxide film is dark, and it is impossible to obtain a colorless and transparent oxide film.  As the silicon content increases, the color of the anodic oxide film From light gray to dark gray to dark gray.  Therefore, cast aluminum alloy is not suitable for anodizing.

Aluminum-silicon alloy, aluminum-silicon-copper alloy, as the name suggests, its composition is in addition to aluminum, silicon and copper are the main components;  under normal circumstances, the silicon content is between 6-12%, mainly to improve the fluidity of the alloy liquid and reduce shrinkage The role of pores;  the copper content is second only to enhance the strength and tensile force;  the iron content is usually between 0.7-1.2%, within this ratio, the demolding effect of the workpiece is better;  through its composition It can be seen from the composition that this type of alloy is impossible to oxidize and color, and even if desiliconization is used, it is difficult to achieve the desired effect.  For aluminum-silicon alloys or aluminum alloys with a high copper content, the oxide film is more difficult to form, and the resulting film is dark, gray, and poor in gloss. Aluminum-magnesium alloy

The oxide film of aluminum-magnesium alloy is easy to form, and the quality of the film is better.  It can be oxidized and colored.  This is an important feature that distinguishes it from other alloys.  However, compared with wrought aluminum alloy, there are some shortcomings.

1.  The anodic oxide film has duality, with large pores and uneven distribution, which makes it difficult to achieve better anti-corrosion effects;
2.  Magnesium has the tendency to produce hardening and brittleness, reduce elongation, and increase hot cracking, such as ADC5, ADC6, etc.  In production, due to its wide solidification range and large shrinkage tendency, shrinkage porosity and cracks often occur, and casting performance Extremely poor, therefore, there are greater limitations in its scope of use, and workpieces with a slightly complex structure are not suitable for production at all;
3.  The commonly used aluminum-magnesium alloys on the market have complex composition and low aluminum purity.  When sulfuric acid anodizes, it is difficult to produce a transparent protective film.  Most of them are milky white and the coloring state is also poor.  It is difficult to achieve the desired effect according to the normal process.
It can be seen that sulfuric acid anodizing is not suitable for commonly used die-casting aluminum alloys;  however, not all die-casting aluminum alloys can not achieve the purpose of oxidation and coloring, such as aluminum-manganese-cobalt alloy DM32, aluminum-manganese-magnesium alloy DM6, etc., die-casting performance and oxidation Excellent performance.