Authors: Xuezhi Zhang Li Fang Zhizhong Sun Henry Hu Xueyuan Nie Jimi Tjong
Publish Date: 2015/12/24
Volume: 52, Issue: 10, Pages: 2303-2315
Abstract
The heat transfer coefficient at the castingdie interface is the most important factor on the solidification process With the 75ton hydraulic press machine and P20 steel die mold 5step castings of magnesium alloy AM60 with different wallthicknesses 3 5 8 12 20 mm were poured under various hydraulic pressures 30 60 and 90 MPa using an indirect squeeze casting process Thermal histories throughout the die wall and the casting surface have been recorded by fine typeK thermocouples The incavity local pressures measured by pressure transducers were explored at the castingdie interfaces of 5 steps The castingdie interfacial heat transfer coefficients IHTC initially reached a maximum peak value followed by a gradually decline to the lower level Similar characteristics of IHTC peak values can be observed at the applied pressures of 30 60 and 90 MPa With the applied pressure of 90 MPa the peak IHTC values from steps 1 to 5 varied from 5623 to 10649 W/m2 K As the applied hydraulic pressure increased the IHTC peak value of each step was increased accordingly The wall thickness also affected IHTC peak values significantly The peak IHTC value and heat flux increased as the step became thicker The empirical equations relating the IHTCs to the local pressures and the solidification temperature at the casting surface were developed based on the multivariate linear and polynomial regression
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