Options for Gas Quenching

摘要

Gas quenching in vacuum furnaces is becoming increasingly attractive because it has a low environmental impact and minimizes the distortion of parts being treated. Whilst nitrogen is by far the most common quenching gas, other gases such as helium and hydrogen are alternatives where higher cooling rates are required, particularly for carburized components. Argon is also an option, especially for materials that are sensitive to nitriding during quenching, or when a high cooling rate is not required, such as high alloy tool steels. In some applications gas mixtures would be technically beneficial, but this area is fraught with patent and cost-effectiveness issues. This paper summarizes the physico-chemical background to variations in the quenching performance of the different gases and their applicability to quenching a range of steels. Their cost-effectiveness as quenchants is explored, both in terms of the costs of the gases themselves and of the equipment needed to employ them.