Determination of solid fraction-temperature relation and latent heat using full scale casting experiments: application to corrosion resistant steels and nickel based alloys

Casting simulation results are only useful to a foundry if they reflect reality, which requires accurate material datasets for the alloys being simulated. Material datasets include property data such as density, specific heat and thermal conductivity as functions of temperature, as well as latent heat of solidification and a solid fraction-temperature relation. Unfortunately, there are a significant number of commonly used metal alloys for which no reliable material data are available. The present study focuses on five such corrosion resistant alloys: superaustenitic stainless steel CN3MN, duplex stainless steels CD3MN and CD4MCuN and nickel based alloys CW6MC and N3M. Initial alloy material datasets are generated using thermodynamic simulation software. Comparisons of temperatures measured in full scale sand castings made from these alloys with temperatures predicted in computer simulations revealed that these initial datasets are inadequate. Therefore, an iterative method is developed to adjust the datasets (in particular the solid fraction-temperature relation and latent heat) in order to match measured and predicted temperatures and cooling rates. Uncertainties in the simulation are effectively eliminated through parametric studies. Although more tedious, the present iterative method to determine the solid fraction-temperature relation and latent heat is believed to be more accurate than traditional cooling curve analysis using small experimental castings.