Inclusions (Slag)

Inclusions (Slag)Slag inclusions present as missing areas (a mix of round, irregular or angular shaped craters or cavities) of metal in the casting or black, crusty particles sitting on the metal surface. This defect indicates a presence of liquid and solid slag inclusions; which are being carried into the shell by the metal.

The causes of this defect are evident in the metal and other portions of the process. To cure these causes, R&R recommends taking the following actions.

 

Area

Cause

Cure

Wax

 

 

Shell

 

 

Metal

  1. Poor deslagging.
  2. Poor deoxidation and/or poor deslagging practice. When molten metal is exposed to air, it begins to oxidize, forming slag.
  3. Metal overheat.
  1. Determine proper temperature and control.
  2. Improve deoxidation and/or deslagging technique, and limit metal exposure to oxygen during pouring.
  3. Cast at lowest possible temperature.
  4. Use a filter to remove slag from metal during pouring.

Other

  1. Poor condition of refractory liners in ladles and furnaces (moisture).
  2. Improper deoxidation.
  3. Contamination from casting ladle or turbulent casting.
  4. Poor deslagging practice.
  1. Check on firing of new refractory linings.
  2. Improve deoxidation.
  3. Inspect ladles and avoid turbulence.
  4. Use proper deslagging practices.

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