Study On The Casting-die Interfacial Heat Transfer Behavior And Pressure Transmission In Squeeze Casting

Squeeze casting is an advanced near net process technology for manufacturing of high performance mechnical components.The casting-die interfacial heat transfer and pressure transmission are the essential physics problems in squeeze casting.Therefore,it is of great value and academic significance to investigate the casting-die interfacial heat transfer behavior and pressure transmission in squeeze casting.In this paper,a rigorous method for measuring the mold temperature and interfacial pressure has been established through mold and casting design,temperature sensor unit design,accurate installation of pressure transducer and implementation of squeeze casting experiments.Through a low pass filtering method based on Fast Fourier Transform(FFT),the acquired temperature data were pre-processed,and based on the temperature measurements inside the die,the interfacial heat transfer coefficient(IHTC)at the metal-die interface was determined by applying an verified inverse approach.A systematic method was established for obtaining the quantitative IHTC data and interfacial pressure in squeeze casting.By using the established method,the IHTC and interfacial pressure under various process conditions were investigated,and the effect of applied pressure,pouring temperature,the initial die temperature and coating thickness on the interfacial heat transfer was revealed.Based on the theory of micro-geometry/contact mechanics,a model describing the interfacial heat transfer behavior at the casting-die interface in squeeze casting was established,in which the contact stress,effective heat transfer area,mechanical and thermal properties of materials were taken into account.Based on the experimental data,the quantitative relationship between the IHTC and the interfacial pressure and temperature was determined.Besides,the IHTC model after the interface pressure decreased to zero was obtained by fitting IHTC and the interface temperature acquired from the squeeze casting experiments.Through experimental and numerical study,the whole process of how the solidification and mechanical properties of the materials affected the pressure transmission in squeeze casting process was revealed.By comparing the results of magnesium alloy and aluminum alloy,the difference of their influence on the pressure transmission in squeeze casting process was revealed,which provided important guidance for squeeze casting process design.