Influence of Process Parameters on Cooling Conditions in Nickel Base Superalloy Investment Casting

Abstract

The published results of the research on crystallization process of nickel base superalloy castings rarely take into account the effect of the wall thickness of the casting. Current study presents a comprehensive assessment of the impact of molten alloy temperature, mould temperature, mould thermal insulation and casting diameter on crystallization process of polycrystalline nickel base superalloy. Research was designed and conducted as an factorial experiment at two levels. Different diameter samples were designed and optimised by the numerical simulation of solidification process using ProCAST software. Inconel 713C nickel based superalloy was cast into alumina-silicate moulds produced by lost wax technique. Casting temperature during solidification was measured using thermocouples installed in sections having a diameter of 10 and 20 mm. Statistical analysis of the influence of the main process parameters and casting diameter on cooling rate, total freezing temperature range and critical temperature range was performed. Cooling rates in the range from 0.21 to 1.24°C/s were obtained. It was found that diameter of the casting, mould temperature and the thermal insulation of the mould had significant effect on the cooling rate.