TY - JOUR
T1 - Effects of the entrained surface film on the reliability of castings
AU - Mi, Jiawei
AU - Harding, Richard
AU - Campbell, John
PY - 2004/9/1
Y1 - 2004/9/1
N2 - The tilt pouring and gravity top pouring of an Al-4.5 pct Cu alloy have been studied. A computer-controlled rollover casting wheel was used to perform the tilt pouring. Filling sequences with tranquil or turbulent flow patterns have been visualized using real-time X-ray video radiography and modeled using a computational fluid dynamics (CFD) code. The area of the free surface film entrained into the bulk of liquid metal in different filling conditions has been calculated using a filling sequence free from surface turbulence as a baseline. The tensile properties of the castings have been quantitatively assessed for reliability using a two-parameter Weibull distribution function. The study reveals that the liquid metal flow in the mold filling process can be accurately simulated using a CFD code. In addition, the computed total surface area of the entrained surface film can be used as a criterion to judge the deterioration of reliability. The high Weibull modulus achieved by filling a mold without surface turbulence was reduced by a factor of 2.5 of its original value by entrained surface films. Entrainment of bubbles required surface turbulence, but folded films could be entrained simply by contraction of the free surface, creating excess surface film that necessarily folds inward.
AB - The tilt pouring and gravity top pouring of an Al-4.5 pct Cu alloy have been studied. A computer-controlled rollover casting wheel was used to perform the tilt pouring. Filling sequences with tranquil or turbulent flow patterns have been visualized using real-time X-ray video radiography and modeled using a computational fluid dynamics (CFD) code. The area of the free surface film entrained into the bulk of liquid metal in different filling conditions has been calculated using a filling sequence free from surface turbulence as a baseline. The tensile properties of the castings have been quantitatively assessed for reliability using a two-parameter Weibull distribution function. The study reveals that the liquid metal flow in the mold filling process can be accurately simulated using a CFD code. In addition, the computed total surface area of the entrained surface film can be used as a criterion to judge the deterioration of reliability. The high Weibull modulus achieved by filling a mold without surface turbulence was reduced by a factor of 2.5 of its original value by entrained surface films. Entrainment of bubbles required surface turbulence, but folded films could be entrained simply by contraction of the free surface, creating excess surface film that necessarily folds inward.
UR - http://www.scopus.com/inward/record.url?scp=6944225392&partnerID=8YFLogxK
U2 - 10.1007/s11661-004-0237-y
DO - 10.1007/s11661-004-0237-y
M3 - Article
SN - 1073-5623
VL - 35A
SP - 2893
EP - 2902
JO - Metallurgical and Materials Transactions A
JF - Metallurgical and Materials Transactions A
ER -