TY - GEN
T1 - Microporosity evolution and interdendritic fluid flows during solidification
AU - Sabau, Adrian
AU - Viswanathan, Srinath
PY - 2001
Y1 - 2001
N2 - In general, the occurrence of microporosity during metal casting is due to the combined effects of solidification shrinkage and gas precipitation. The governing equations for fluid flow and hydrogen evolution indicate that porosity formation and fluid flow are strongly coupled. However, in most studies on microporosity, it is considered that the porosity formation does not influence the fluid flow in the mushy zone. In this study, a computational methodology is presented for the numerical simulation of interdendritic fluid flow and microporosity evolution. The solution algorithm presented includes a fully coupled, implicit treatment of microporosity and local pressure in the mushy zone. The effects of microporosity evolution due to the local pressure drop in the mushy zone, and pore expansion in casting regions where liquid feeding alone cannot compensate for the solidification shrinkage are also considered. It is shown that neglecting the effect of porosity formation on the pressure in the mushy zone yields higher pressure drops. By its growth, microporosity partially compensates for the solidification shrinkage, reducing the feeding demand. A reduced feeding demand requires less fluid flow to compensate for solidification shrinkage, and results in smaller pressure drops in the mushy zone. Therefore, in order to accurately describe casting defects, comprehensive models of fluid flow, heat transfer, and solidification must include the effect of microporosity as well.
AB - In general, the occurrence of microporosity during metal casting is due to the combined effects of solidification shrinkage and gas precipitation. The governing equations for fluid flow and hydrogen evolution indicate that porosity formation and fluid flow are strongly coupled. However, in most studies on microporosity, it is considered that the porosity formation does not influence the fluid flow in the mushy zone. In this study, a computational methodology is presented for the numerical simulation of interdendritic fluid flow and microporosity evolution. The solution algorithm presented includes a fully coupled, implicit treatment of microporosity and local pressure in the mushy zone. The effects of microporosity evolution due to the local pressure drop in the mushy zone, and pore expansion in casting regions where liquid feeding alone cannot compensate for the solidification shrinkage are also considered. It is shown that neglecting the effect of porosity formation on the pressure in the mushy zone yields higher pressure drops. By its growth, microporosity partially compensates for the solidification shrinkage, reducing the feeding demand. A reduced feeding demand requires less fluid flow to compensate for solidification shrinkage, and results in smaller pressure drops in the mushy zone. Therefore, in order to accurately describe casting defects, comprehensive models of fluid flow, heat transfer, and solidification must include the effect of microporosity as well.
UR - http://www.scopus.com/inward/record.url?scp=0035788893&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:0035788893
SN - 0873395131
T3 - Proceedings of the Conference on Computational Modeling of Materials, Minerals and Metals Processing
SP - 725
EP - 734
BT - Proceedings of the Conference on Computational Modeling of Materials, Minerals and Metals Processing
A2 - Cross, M.
A2 - Evans, J.W.
A2 - Bailey, C.
A2 - Cross, M.
A2 - Evans, J.W.
A2 - Bailey, C.
T2 - Proceedings of Conference on Computational Modeling of Materials, Minerals and Metals Processing
Y2 - 23 September 2001 through 26 September 2001
ER -
