5. Examples of vacuum metallurgy

5.1 General

Vacuum metallurgy is playing an increasingly important role in the development of steels and specific cast alloys with improved properties. In fact, the idea of vacuum metallurgy is not new: as far back as the last century, BESSEMER pointed out the dangers of gas in liquid steel, and indicated that these could be eliminated by placing the steel ladle in a vacuum chamber. But it is only in the last forty years or so that these new techniques have been applied to the industrial production of special alloys, and in the last twenty years or so to the production of large masses of wrought steel. This delay is essentially due to technological difficulties that have only been overcome by considerable progress in vacuum production.

In steel casting, there...