热处理对挤压铸造AlCu5Mn1Mg铝合金飞轮壳 微观组织和力学性能的影响

As a key load-bearing component of automobiles, the mechanical properties of the aluminum alloy flywheel housing can be effectively improved by heat treatment. An X-ray fluorescence spectrometer (XRF), an optical microscope (OM), a scanning electron microscope (SEM), a 20 kN universal tensile testing machine, and a hardness tester were used to investigate the changes of microstructure and mechanical properties of AlCu5Mn1Mg aluminum alloy flywheel housing before and after heat treatment. The results show that the as-cast sample has fine, dense grains, and is mainly composed of a large number of α-Al with rosette and equiaxed morphologies and non-equilibrium eutectic phases. With the increase of solution temperature, the second-phase particles at the grain boundaries are gradually dissolved into the aluminum matrix. However, an excessively high solution temperature leads to grain coarsening and grain coalescence, which reduces the mechanical properties of the material. With the extension of solution time, the alloying elements at the grain boundaries diffuse into the interior of grains and distribute uniformly, and the grain size increases simultaneously. The Portevin-Le Chatelier (PLC) effect is observed in the tensile curve after aging at 180 ℃ for 5 h. The optimal heat treatment process for the squeeze-cast AlCu5Mn1Mg aluminum alloy flywheel housing component is determined as follows: solution treatment at 495 °C for 10 h followed by aging treatment at 140 ℃ for 5 h.