Oxidation slag inclusion
（aluminum casting)
Defect characteristics: oxide slag inclusions are mostly distributed on the upper surface of the casting and at the airtight corner of the mold. The fracture is mostly gray white or yellow, which can be found by X-ray fluoroscopy or machining, or by alkali washing, pickling or anodizing
Causes
(aluminum casting)
1. The furnace charge is not clean and the amount of returned material is too much
2. Poor design of gating system
3. The slag in the alloy solution is not removed completely
4. Slag inclusion is brought in due to improper pouring operation
5. Insufficient standing time after refining and modification
Prevention methods
（aluminum casting)
1. The furnace charge shall be subject to sand blowing, and the use of returned charge shall be reduced appropriately
2. Improve the design of gating system and its slag retaining capacity
3. Use appropriate flux to remove slag
4. During pouring, it shall be stable and pay attention to slag retaining
5. After refining, the alloy liquid shall stand for a certain time before pouring
