Concept

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 content, 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 employed 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.

References