Gas absorption in grey cast iron during mould filling

Abstract

The effect of mould filling on the hydrogen and nitrogen concentration in grey cast iron has been investigated. A special mould was designed and the influence of several process and mould parameters, such as degree of turbulence, permeability, core binder and coatings, were studied. The hydrogen concentration increased during mould filling and the absorption was favoured by turbulent filling, low permeability and larger gas evolution from the mould and cores. In some cases, the hydrogen concentration in the iron after mould filling almost reached the solubility limit, which increases the risk that gas precipitates during solidification.

Exact values of the influence of mould filling on the nitrogen concentration could not be obtained, but some observations could still be conducted. The absorption of nitrogen seemed to be favoured by the same parameters as hydrogen.

Keywords:

• GREY CAST IRON
• MOULD FILLING
• GAS ABSORPTION
• HYDROGEN
• NITROGEN
• TURBULENCE