Some appearance inspection of die cast aluminum machining

As many of you know, aluminum and aluminum alloys are considered ideal materials for future cars.  As for aluminum, the application of die-cast aluminum processing parts will greatly reduce the quality of the vehicle, improve the power performance of the vehicle, and reduce the emission of pollutants. 
However, there is a big gap between the bearing capacity of aluminum and steel, and due to the limitations of current production technology, the cost of aluminum is high, which limits its application in automobiles. 

The defect characteristics, causes and prevention methods of aluminum alloy die casting: name flow mark and pattern, network, hairwings, brittle crack, shrinkage cavity and porosity characteristics and inspection methods.

Appearance inspection: 
1. There are stripes on the surface of aluminum alloy die casting in the same direction as the flow of liquid metal, and there are clearly visible lines with no direction different from the color of the metal matrix, and no development trend. 
2. There are raised or concave marks on the surface of the die casting part like mesh hair, which will expand and extend with the increase of the number of die casting.
3. The alloy grain is coarse or very small, so that the casting is easy to fracture or shatter.
4. When the casting is placed in alkaline solution, the crack is dark gray. The damage and crack of the metal matrix are straight or wavy, and the grain is narrow and long.
Anatomical appearance examination or flaw detection;  The surface of the shrinkage cavity is dark and not smooth, and the shape of the holes is irregular. The large and concentrated holes are shrinkage holes, and the small and scattered ones are shrinkage porosity.