Study On The Heat Treatment Strengthening And Heat Dissipation Performance Of Water-cooling Shell For New-energy Vehicles

With the rapid development of automobile industry,new energy vehicles are rapidly occupying the domestic automobile market.Based on the concept of energy saving,emission reduction and vehicle lightweight,new energy vehicles adopt the integral cast aluminum motor shell instead of the original welded cast iron motor shell.However,at present,there are still some technical problems such as low strength,poor fatigue resistance and impact resistance.In this paper,the heat treatment process of the cast aluminum alloy shell is studied,and the mechanical properties and fatigue properties of the shell aluminum alloy are analyzed.The impact resistance of the shell is studied by SHPB and integral impact test.At the same time,combined with numerical simulation and experimental test,the heat dissipation performance of water-cooled shell under different heat treatment processes is analyzed,and the following conclusions are obtained:(1)The main strengthening phase of Al-Si-Mg-Cu alloy is β″ phase.When the alloy is in the peak state of T6 and T6I6,the main precipitation phase is β″ phase and GP zone.During the over-aging period,the β″ phase will gradually evolve into β′ phase and Q′,eventually forming a stable β and Q phase.Under the heat treatment process of T6I6,the mechanical properties and fatigue properties of the alloy were the highest.(2)The dynamic mechanical properties of T6I6 heat-treated alloy are better than that of T6.When the strain rate is 2000s-1,the absorption energy of T6I6 alloy is 10.34mj/m3 higher than that of T6 alloy.When the strain rate rises to 5000s-1,the increase reaches 20.34mj/m3.At the same time,the number of microcracks in T6I6 alloy is less after impact.In the process of sled impact test,the whole deformation of T6I6 heat treatment shell is more uniform than that of T6 shell,and it can bear stronger impact.(3)Compared with T6 alloy,T6I6 alloy has better thermal conductivity.The numerical simulation results show that the change trend of the temperature field of the shell is basically the same under different heat source temperatures,the lowest temperature appears at the water inlet and the range of change is not large,while the highest temperature of the shell is mainly concentrated at the two ends of the shell near the inner wall.At the same time,with the increase of the external environment temperature,the lowest temperature of the shell after circulating cooling water gradually increases.