Effect of cooling rate on macro- and microstructure of thin-walled nickel superalloy precision castings

Abstract

The macro- and microstructure of nickel superalloys castings, especially thin-walled ones, have a large influence on their mechanical properties. Better understanding of the macro- and microstructure response to casting conditions will enable the optimization of technological and mechanical properties of the alloy. Presented research results refer to different diameter cylindrical specimens of Inconel 713C superalloy cast under various conditions to impose different cooling rates. The function model for correlation between secondary dendrite arm spacing (SDAS) and cooling rate was proposed. Statistical analysis of the influence of the main casting process parameters on the SDAS and cooling rate on grains morphology was performed. It was found that casting diameter had a biggest impact on the SDAS while mold temperature and thermal insulation had less influence on the alloy microstructure. Quantitative microstructural analysis results indicated also the effect of cooling rate on grain size.