Effect of pressure on metal-die heat transfer coefficient during solidification

Abstract

A combined theoretical and experimental program was carried out to study the effect of applied pressure and die coatings on the heat transfer coefficient at the metal-die interface during solidification of AlSi eutectic alloy against an H-13 die. The castings were unidirectionally solidified in a commercial hydraulic press modified to accept a controlled temperature die set. The die thermal behavior was experimentally determined from thermocouples located at different distances from the metal-die interface. A one-dimensional computer heat flow program was used to correlate measured and simulated die temperatures and hence to deduce the heat transfer coefficients. It was found that application of a pressure of 19.6 × 10⁷ Pa increases the heat transfer coefficient from about 3.4 × 10³ to 5.25 × 10⁴ W m⁻² K⁻¹. The effects of different die coatings on the heat transfer coefficient were also determined.