Determination of Metal/Die Interfacial Heat Transfer Coefficients in Squeeze Casting of Wrought Aluminum Alloy 7075 With Variations in Section Thicknesses and Applied Pressures

Abstract

Squeeze casting of wrought aluminum 7075 was carried out on a 75-ton hydraulic press. Metal/die interface heat transfer phenomena in squeeze casting of the alloy were investigated. To facilitate experimental measurements, a five-step casting mold was designed for the experiments. The five-step casting consisted of five different section thicknesses of 2, 4, 8, 12, and 20 mm. Squeeze casing experiments were performed under the applied hydraulic pressures of 30, 60, and 90 MPa. Temperatures were measured at the casting surface and at various specific locations inside the die. At each step, thermocouples were placed at 2, 4, and 6 mm away from the inside die face. Based on the measured temperature results, the interfacial heat transfer coefficients (IHTCs) and heat fluxes were determined by solving the one-dimensional transient heat conduction equation with the inverse method. With increasing the casting section thicknesses from 2 to 20 mm, the peak IHTC values varied from 1683.46 W/m2 K to 9473.23 W/m2 K, 2174.78 W/m2 K to 13,494.05 W/m2 K, and 3873.45 W/m2 K to 15,483.01 W/m2 K for the applied hydraulic pressures of 30, 60, and 90 MPa, respectively.