What are the defects of gravity casting aluminum alloy?

2020-01-09 10:17:59 438

Defect analysis of gravity casting aluminum alloy. Gravity casting of aluminum alloy is characterized by fluidity, shrinkage, heat, air tightness, casting stress and air absorption. The slag is mainly distributed on the upper surface of the casting, and the corner of the die is not ventilated. The fracture surface is mostly gray white or yellow. It can also be found by X-ray fluoroscopy or machining. In the process of alkaline cleaning, acid pickling or anodizing, it is also found that the pores on the wall of three kinds of castings are generally round or oval, with smooth surface, glossy oxide skin and sometimes yellow oil. Air holes and bubbles can be found on the surface by sandblasting, and black air holes can be found on the X-ray film by X-ray fluoroscopy or machining.

It refers to that the shrinkage porosity of aluminum castings generally occurs at the joint of the thick part, wall thickness, wall thickness and wall thickness near the root of the flying riser of the internal sprue, and the large plane of the wall thickness and wall thickness. As cast fracture is gray, gray white light yellow or gray black light yellow after heat treatment. Through X-ray and fluorescence low power fracture detection, it is found that the filamentous shrinkage on X-ray film is serious.

Gravity cast aluminum is usually divided into two situations. Casting cracks. The development along the grain boundary is often accompanied by segregation, which is a kind of crack formed at a higher temperature. It is easy to appear in alloys with larger volume shrinkage and castings with more complex shapes. Supercooling often occurs in alloys with high stress and high coefficient of thermal expansion. It is found that the most common defect of die casting is porosity. Stomatal characteristics. It has a smooth surface and is round or oval in shape. The expression can be on the surface of the casting, under the skin pinhole of the casting, or inside the casting.

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