Determination of Interfacial Heat Transfer Behavior at the Metal/Shot Sleeve of High Pressure Die Casting Process of AZ91D Alloy

The interfacial heat transfer behavior at the metal/shot sleeve interface in the high pressure die casting（HPDC） process of AZ91 D alloy is carefully investigated.Based on the temperature measurements along the shot sleeve,inverse method has been developed to determine the interfacial heat transfer coefficient in the shot sleeve.Under static condition,Interfacial heat transfer coefficient（IHTC） peak values are 11.9,7.3,8.33 k W m-2K-1at pouring zone（S2）,middle zone（S5）,and end zone（S10）,respectively.During the casting process,the IHTC curve displays a second peak of 6.1 k W m-2K-1at middle zone during the casting process at a slow speed of 0.3 m s-1.Subsequently,when the high speed started,the IHTC curve reached a second peak of 12.9 k W m-2K-1at end zone.Furthermore,under different slow casting speeds,both the calculated initial temperature（TIDS） and the maximum temperature（Tsimax） of shot sleeve surface first decrease from 0.1 m s-1to 0.3 m s-1,but increase again from 0.3 m s-1to 0.6 m s-1.This result agrees with the experimental results obtained in a series of "plate-shape" casting experiments under different slow speeds,which reveals that the amount of ESCs decreases to the minimum values at 0.3 m s-1and increase again with the increasing casting slow speed.