One of the main shortcomings of atmospheric smelting (vacuum furnace) and pouring is that alloy composition (mainly some active elements) can not be accurately controlled due to burning loss, while vacuum smelting is not polluted by ambient atmosphere, and liquid metal is separated from oxygen and nitrogen in the atmosphere. Therefore, vacuum smelting can strictly control the content of active elements in alloy, such as Al, Ti, etc., and control alloy composition in a very narrow range. In this way, the properties, quality and stability of the alloy can be guaranteed.vacuum-induction-melting-and-deoxidation-of-nickel-base-superalloy
Carbon-oxygen reaction in atmospheric smelting plays a degassing and mechanical stirring role on liquid metal. However, due to the weak deoxidizing ability of carbon, it can not be used as deoxidizer alone, so precipitation deoxidization is often carried out with metal deoxidizers such as silicon and aluminium. In vacuum smelting, because of the low gas pressure and the continuous extraction of CO bubbles generated by carbon-oxygen reaction, the equilibrium moves towards the direction of CO formation, i.e. [C]+[O]={CO} reaction proceeds continuously to the right, which improves the deoxidization ability of carbon. A large number of practical data show that the deoxidization capacity of carbon in vacuum melting is about 100 times higher than that in atmospheric melting. In vacuum melting of nickel-based alloys, it is not difficult to reduce the oxygen content of the alloys to less than 20 x 10. Carbon deoxidation under vacuum not only has high deoxidizing capacity, but also its deoxidizing product is gas, easy to remove, and does not contaminate the metal melting pool. This is much superior to the deoxidizer which produces solid deoxidizing products with silicon and aluminium. Therefore, carbon is an ideal deoxidizer in vacuum melting.heat-treatment-of-skd61-die-steel/
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