Defects in the grey iron castings caused by core-gas penetration into the melt has since long time been a challenge for foundry technologists and researchers [1-3] despite using core/mould coatings, which can on some sand surfaces be burned out, thereby causing the open-pore conditions towards the metal domain. A simplified finite-element model to predict necessary conditions for core-gas penetration into the cast iron during the mould filling stage has been developed and modelling assumptions have been discussed. Cooling and metal pressure (pm) curves prior to solidification are adopted from the full-scale mould filling simulation of an industrial iron cast component. Binder decomposition kinetics data including several chemical reactions have been obtained from the TGA measurements on the organic binder samples, used in FURAN foundy sand. Gas generation as result of binder decomposition, Darcian flow and heat transfer by conduction and convection inside the sand domain have been modelled. Two regions of the sand mould at different heights (upper and lower), Figure 1a, with respect to gravity have been compared.  The simulations enable prediction of the instant gas pressure(pgas) distribution in the sand core/mould, Figure 1b, and comparison with the external simulated pressure in the melt during the mould filling. The time range of the potential risk for the core-gas penetration into the melt has been determined, taking into account the sand pore morphology and capillary pressure (pc), Figure 1c. Performed parametric studies highlight the importance of considering multiple binder decomposition reactions to obtain the realistic gas pressure distributions in the sand core/mould.

References
[1] C.E. Bates; R.W. Monroe AFS Transactions, 1981, vol. 89, pp. 671-686.
[2] P. Scarber; C.E. Bates; J. Griffin AFS Transactions, 2006, vol. 114, pp. 435–445.
[3] M.D. McKinley; C.A. Lytle; W. Bertsch AFS Transactions, 1999, vol. 107, pp. 407-412.