Foundation and application of Al-Zn-Mg-Cu alloy flow stress constitutive equation in friction screw press die forging

Flow stress behavior of extruded Al-5.7Zn-1.9Mg-1.5Cu alloy bar was studied by thermal compression test with temperature and strain rate ranging from 300 degrees C to 450 degrees C and 0.01 s(-1) to 10 s(-1) respectively. It was founded that the characteristic of flow stress during 350-450 degrees C can be described by exponential correlation with activate apparent energy of 152 kJ/mol. With the founded constitutive equation, the die forging processing of a connecting rod in friction screw press was simulated with DEFORM-3D software. The optimum preheat temperature of die forging process are 425 degrees C for billet, and 200 degrees C for container. The simulation of the hot forming process shows good agreement with experiments results of geometry and streamline of the workpiece. (C) 2012 Elsevier Ltd. All rights reserved.