Why are aluminum die casting defects prone to oxidation and slag formation as opposed to other materials

When the casting is completed, the oxidized slag is primarily distributed on the casting's upper surface, particularly at the corners of the casting mold, where no air is allowed to pass through. The fracture is typically grayish-white or yellow in color, and it is discovered through X-ray fluoroscopy or mechanical processing in the majority of instances. Alkaline washing, pickling, and anodizing are all processes that can reveal the presence of this substance.
 

The following are the reasons for this:1. The furnace charge is not clean, and the amount of back charge is excessive compared to other charges.

The introduction of slag occurs as a result of an incorrect pouring operation.
The insufficient amount of standing time following the refinement and deterioration treatments, respectively.

The following are recommended methods of prevention: 1. The amount of furnace charge that is used should be reduced in an appropriate manner.

Make improvements to the design of the gating system in order to increase the slag retention capability of the system. 
In order to remove slag, make use of the appropriate flux. 
During the pouring process, it is critical to maintain stability while paying close attention to slag blocking.

Following refinement, the alloy liquid should be allowed to stand for a specified amount of time before being poured into the mold. 6)

The exact reason why aluminum die casting defects oxidize and slag is still a mystery to researchers.

The following are examples of preventive measures for aluminum alloy die casting defects caused by oxidation and slag inclusion in die castings:

Control the smelting process of aluminum alloy castings to ensure that they are smelted quickly, that oxidation is reduced, and that slag is completely removed from the finished product. It is necessary to melt the Al-Mg alloy beneath the covering agent in order for it to adhere properly. After coating, aluminum die castings is necessary to clean and remove oxides from the furnace and tools, as well as preheating the furnace and tools. After coating, the paint must be allowed to dry completely before use. aluminum die casting is essential that the pouring system that has been designed has features such as stable flow, buffering, and slag skimming capabilities, among others. Because of the use of an inclined pouring system, the liquid flow is stable, and there is no secondary oxidation as a result of the use of the system. The paint that is selected should have excellent adhesion and should not peel off during the pouring process, otherwise slag inclusions in the aluminum alloy castings will form during the casting process, resulting in poor casting quality.

Die castings in the ADC11 or ADC12 series are commonly used in aluminum casting.  is composed of the following elements, according to its chemical composition: ADC11 is composed of the elements:

Both the chemical composition of the ADC11 Slag inclusion form and the mechanism by which die casting aluminum is formed are investigated.

Die casting defects in aluminum alloys, such as oxidation and slag inclusion, are caused by a combination of factors, which are as follows:

In addition, the amount of back charge appears to be excessive, indicating that the charge is not clean.
Design flaws in the gating system's construction
In the alloy liquid, there is no cleaning of the slag at all.
As a result of an incorrect pouring operation, slag is introduced into the system.
An insufficient amount of standing time after refining and deterioration treatment
Based on the analysis of scrap parts from aluminum alloy die-casting, it has been discovered that there are three main types of slag inclusions in the gate: shrinkage cavity inclusions, oily dirt inclusions, and chilled layer inclusions. Oily slag inclusions account for more than 60% of the total slag inclusions, while the chilled layer accounts for approximately 35% of the total slag inclusions and the shrinkage cavity type accounts for less than 5% of the total slag inclusions, according to the results.

Slag inclusion in the gate of a die casting has an appearance that is similar to shrinkage defects in a die casting. Slag inclusion in the gate of a die casting has an appearance that is similar to shrinkage cavity inclusion in a die casting.

After the runner cake of aluminum alloy die-casting parts was knocked off, the irregular shape, relatively clean inside, and rough surface that appeared to be shrinkage-like holes appeared at the gate after the runner cake was knocked off. In aluminum alloy die castings with shrinkage cavities and slag inclusions, it is sunken on the gate surface. Even after polishing and coating, the appearance is not smooth. Due to the high inner gate temperature (the measured maximum mold temperature is 380°C) and the fact that it is the last solidified part, the Al liquid is too late to feed, resulting in shrinkage defects and Al liquid being too late to feed, respectively.