Selected Aspects of the Use of Thermal & Derivative Analysis to Improve Macro Modeling of Solidification for Casting Iron. Comparison of Chosen Simulation Codes

Abstract

The article concerns the influence of grey cast iron density and different trials of fraction of solid curves (influencing latent heat generation) on the formation of shrinkage discontinuities. Two alternatives of density curves were considered (Rho=f(T)): the classical one, (usually applied in macro model simulation codes) and the modified one, which includes graphite expansion (based on compensation of primary shrinkage discontinuities during eutectic phase crystallization). Solid fraction curves applying Newtonian Thermal Analysis (NTA) were estimated. The experimental and numerical simulation tests were performed on the castings, which were made with Derivative Thermal Analysis (DerTA) standard cups and in furan-bonded sand cube mould of 250 mm side and a upper riser 140x200 mm The numerical tests were realized using NovaFlow&Solid (NF&S) and ProCast codes. Also, some tests were realized using ProCast with a micro model (default value parameters). In this work, the coupled influence of both curves on the dynamics of the shrinkage-expansion phenomena and on shrinkage defects prognosis in grey cast iron castings has been revealed.