Effect of T6I6 treatment on dynamic mechanical behaviour of Al-Si-Mg-Cu cast alloy and impact resistance of its cast motor shell

T6I6处理对Al-Si-Mg-Cu合金及其铸造电机机壳动态力学行为和抗冲击性能的影响

The effect of T6I6 treatment on the dynamic mechanical and microstructure behaviour of Al-Si-Mg-Cu cast alloy was investigated using split Hopkinson pressure bar(SHPB), transmission electron microscopy(TEM), and highresolution transmission electron microscopy(HRTEM). Besides, the impact resistances of T6I6 and T6 motor shells of new energy vehicles made of Al-Si-Mg-Cu cast alloy were compared using a trolley crash test. The results indicated that the main strengthening-phases of the T6 peak-aged and T6I6 peak-aged alloy were GP zone and β″ precipitates. T6I6treatment can increase the density and size of β″ precipitates in peak-aged alloy and enhance both its tensile strength(σb)and elongation(δ). The dynamic toughness values of T6I6 samples are 50.34 MJ/m^(3) at 2000 s^(-1) and 177.34 MJ/m^(3) at 5000 s^(-1) which are 20% and 12% higher than those of T6 samples, respectively. Compared with a T6 shell, the overall deformation of T6I6 shell is more uniform during the crash test. At an impact momentum of 3.5×10;kg·m/s, the T6I6shell breaks down at 0.38 s which is 0.10 s later than the T6 shell.

采用分离式霍普金森压杆(SHPB)、透射电镜(TEM)和高分辨透射电镜(HRTEM)研究了T6I6处理对Al-Si-Mg-Cu铸造合金动态力学行为和显微组织的影响。通过台车碰撞试验,比较了Al-Si-Mg-Cu铸造的新能源汽车发动机机壳分别经过T6I6和T6处理后的抗冲击性能。结果表明,T6峰时效合金和T6I6峰时效合金的强化相主要为GP区和β″相。T6I6处理能增加合金中β″相的密度和体积,从而提高合金的抗拉强度(σb)和伸长率(δ)。T6I6试样在2000 s^(-1)和5000 s^(-1)应变速率下的动态韧性分别为50.34 MJ/m^(3)和177.34 MJ/m^(3),比T6试样的分别高20%和12%。与T6机壳相比,T6I6机壳在碰撞试验中的整体变形更加均匀。当冲击动量为3.5×10;kg·m/s时,T6I6壳体在0.38 s时发生破裂,比T6壳体晚0.10 s。