The Strucure Of 2024 Aluminum Alloy Under Instantaneous Large-Current And Hot Deformation Behaviour

The 2024 aluminum alloy takes a very important position with its excellent conductivity, high strenth and low cost. The aim of the paper is to research the main factors through investigation the microstructure of the alloy after instantaneous large-current impacting. So as to establish new methods to improve its harmful effect. At the same time, we do some research on hot deformation with the equipment of thermal simulator.It's proved that the grain size of samples decreased with the increasing of current intensity. A piece of remelted layer was formed on the surface of samples which were doted with voides induced by hydrogen. Both of the density and size of these voides increased with the decreasing of distance from the surface of samples. On the other hand we found intergranular cracks near the surface of samples from the metallograph. Microcracks and melted grain bounderies were found on the SEM graph, so we concluded that the high-temperature oxidation was the main factor effected intergranulars. Near the surface, continuous intergranular cracks were found on the grain boundary which was induced by high temperature, large temperature gradient and complicated contact stress.The grain size near surface and depths of affected zone decreased with the increasing of current intensity which related with the samples'velocity and systerm's cooling rate. The hardness of samples desreased with increasing of depth from edged.The research on hot deformation behavior of 2024 aluminum alloy show that the activity energy is 134.07 kJ/mol, apparent stress exponent is 4.6., from which we can determined thermal deformation equation, strain sensitive index(m), efficiency of power dissipation(η), instability parameter(ζ)and establishing thermal processing maps. According to the thermal processing maps, we deduced that temperature from 400℃to 500℃and the strain rate between 0.01 and 0.1s-1 were the optimal processing zone.