vacuum degassing process

...The vacuum treatment of molten metal reduces the partial pressure P of the gas, so the amount of gas dissolved in the molten metal W is reduced and degassing is achieved. Vacuum degassing processes for molten metal include the ladle degassing process, in which the tapping ladle is placed in a vacuum vessel to degas and then held at 2-20mmHg before casting, the vacuum droplet degassing process, in which the molten metal is poured as fine droplets into a ladle or mold placed in a vacuum vessel (1-10mmHg), the vacuum circulation degassing process, in which the molten metal is circulated between the ladle and the vacuum vessel, and the vacuum suction degassing process, in which the molten metal in the ladle is repeatedly sucked up into the vacuum vessel (see figure). Small ingots or castings are melted and cast in a vacuum vessel. ...

*Some of the terminology that refers to the "vacuum degassing process" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…溶融金属を真空処理することは，ガスの分圧Pを小さくすることなので，溶融金属に溶解するガス量Wが減少して脱ガスが達成される。溶融金属の真空脱ガス法vacuum degassing processには，出鋼取鍋（とりなべ）を真空容器に入れて排ガスし，2～20mmHgに保持してから鋳造する取鍋脱ガス法，真空容器内(1～10mmHg)に設置した取鍋または鋳型に溶融金属を細かい液滴として注入する真空流滴脱ガス法，溶融金属を取鍋と真空容器との間を循環させる真空循環脱ガス法，真空容器に取鍋中の溶融金属を吸い上げることを繰り返す真空吸上げ脱ガス法などがある（図）。小重量の鋳塊または鋳物は，真空容器内で溶解，鋳造が行われる。…

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