| With the incessant development of aerospace industry as the material of aircraft structure parts, such as plate, extrusion part, free forging and die forging, the aluminum alloy’s demand was increasing and its performance requirements became more stringent. While the performance requirements of aluminum components were ensured, the life should be ensured, so that every step of their production should not have fracture risk. In the forging process, the temperature and strain rate would have a serious impact on the high temperature tensile performance and fracture behavior of aluminum. Currently, the study for the high temperature tensile performance and fracture behavior of the new Al-Zn-Mg-Cu high strength aluminum alloy was seldom at home and abroad. Therefore, through combining experimental data and numerical simulation, we studied the high temperature tensile performance and fracture behavior of the new Al-Zn-Mg-Cu high strength aluminum alloy, with a view of providing a guidance to alloy’s performance and fracture control in its forging process. In this paper, through thermal simulation experiment of high temperature tensile and by means of OM, SEM and EDS, the effect of temperature and strain rate on the high temperature tensile properties, fracture behavior,tensile strength, yield strength, true strain at the beginning of necking and true fracture strain of forged and as-cast aluminum was studied. By IBM and regression analysis of experimental data, we had established a model of the change of tensile strength and yield strength with temperature and strain rate, which provide a theoretical basis for ensuring that the equipment’s stress on the material was less than the tensile strength and preventing cracks in developing the forging process. By observing and analyzing microstructure and fracture morphology nearby the fractured specimen fracture, we got the influence law of temperature and strain rate on them and found that the degree of recrystallization increased by the increasing of temperature and the decrease of strain rate. Because the boundaries of recrystallized grain was high angle grain boundaries precipitates was easily gathered at the grain boundaries that could cause intergranular fracture.we should choose a reasonable parameter combination to prevent the occurrence of fracture in the development of the forging process.Through combining high temperature tensile experimental and numerical simulation, using Normalized Cockcroft & Latham criterion simulate stretching process, we got the influence of temperature and strain rate on the crack initiation and fracture damage,which was instructive to the development of forging process of the new Al-Zn-Mg-Cu high strength aluminum alloy. |
