The Vacuum Ingot Casting process is applied to produce forging ingots of 100-800 metric tons. Steels for the production of such ingots should contain very low hydrogen level, typically below 1ppm.

• Sequence casting of several smaller heats into one very large ingot.
• Vacuum degassing of steel takes place during casting (exposing of the poured stream of steel into the vacuum of less than 2 mbar).
• Optionally, liquid steel can be partly degassed in a standard tank type degasser prior to vacuum ingot casting.
• The ingot mold is placed on the bottom of the vacuum tank
• A pony ladle, placed on the vacuum tank cover above the vacuum-tight discharge connection to the vacuum tank acts as a tundish, reducing ferrostatic pressure of the steel flowing into the ingot mold and allowing several ladles to be cast into the same ingot mold.
• Steam Ejector or Mechanical Vacuum Pumps can be used for the generation of the necessary vacuum level during casting.

Technology

• Additional liquid steel temperature losses associated with other vacuum degassing processes are avoided.
• Thanks to the exposing of smaller volumes of steel stream into the vacuum conditions, the efficiency of degassing is higher, which results in a lower level of hydrogen in the ingot.
• Compared with standard casting conditions, additional pick-up of hydrogen from the atmosphere can be avoided.
• Ingots much larger than the furnace capacity of the furnace providing liquid steel can be cast easily.