During the last 25 years, casting process simulation has developed from predicting hot spots and solidification paths to an integral assessment and optimization tool for foundries for the entire manufacturing route of castings.
Modeling cast irons has always been a special challenge due to the strong interdependency between the alloy composition, applied metallurgy and metal treatment with the solidification, phases and structures which form and the resulting properties of the material.
Supporting the risering of the casting is still one of the most important uses of casting process simulation. Different feeding behaviors and self-feeding capabilities of cast irons need to be considered to provide a defect free casting. To be able to quantitatively predict these defects, already in the early 1990’s solidification simulation was coupled to so-called micromodeling. This allowed the consideration of major controlling parameters in the foundry, such as the influence of alloying elements, melting practice and metallurgy, on the special shrinkage and solidification behavior of cast irons. As an additional benefit, the prediction of local structures, phases and ultimately the local mechanical properties of cast irons was available, to assess casting quality in the foundry but also to make use of this quantitative information during design of the casting.
Today, casting quality means more than soundness. A comprehensive list of additional quality issues such as dross or sand inclusions and thermally driven stresses and distortion in castings and cores can be modeled. Cracks in castings can be assessed, as well as the reduction of casting stresses during heat treatment. Increasing demands on material performance has led to increased property requirements for cast irons. The demand for reliable information for new alloys and materials such as CGI, ADI or high-Si ductile cast iron has strongly grown and was addressed by extended modeling capabilities.
All this quantitative information about the material’s performance is most valuable if it can be used during casting design. The transfer of local properties into the designer’s world, to predict local properties such as fatigue strength and durability as a function of the entire manufacturing route, will increase the trust in this old but highly innovative material and will open new opportunities for cast iron in the future.
In each case, the basis for extended modeling and simulation capabilities has been to first gain a fundamental understanding of the formation mechanisms. This requires smart experimentation coupled with the skill to turn empirical and experimental knowledge into quantitative physical models. This paper provides an overview of 25 years of cast iron modeling, which is strongly linked to the achievements and the lifetime dedication of Prof. Ingvar Svensson to cast iron. He has been a pioneer in gaining quantitative understanding to predict cast iron using a computer. The paper will sketch some selected highlights of his work and will provide an outlook to current and future demands on integrated cast iron research to continue to make cast iron a predictable material.
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