脉冲处理对Al-6Zn-3Mg-2Cu合金铸轧板组织及性能的影响

Effects of Electric Pulse Currents on Microstructure and Mechanical Performance of Al-6Zn-3Mg-2Cu Rolled Strip

研究了常规铸轧过程中施加20、50和150Hz频率,电流强度为400A的脉冲电流对Al-6Zn-3Mg-2Cu合金铸轧板的组织及力学性能的影响。结果表明,经20Hz的脉冲电流处理后,Al-Zn-Mg-Cu合金铸轧板偏析情况大为改善,微观组织显著细化;150Hz脉冲电流对铸轧板的组织影响不大;铝合金中τ相广泛分布,呈网状或岛状;同时,经20Hz脉冲电流处理的铸轧板抗拉强度可达320MPa,是常规铸轧板强度的1.3倍;样品具有脆性断裂特征,脉冲处理后韧性有所提高。

The influence of electric pulse(EP)current with frequency of 20,50 and 150 Hz as well as the current density of 400 Aon the microstructure and mechanical properties of Al-Zn-Mg-Cu rolled plate was investigated during solidification process.The results indicate that the macro-segregation degree is greatly improved and the microstructure is obviously refined with 20 Hz EP field.Instead,the structure entirely made up of dendrites has hardly any change at 150 Hz.τphases in form of network or island are widely distributed in aluminum alloy.Meanwhile,the tensile strength of cast rolling strips modified by 20 Hz EP current can reach 320 MPa,which is1.3 times of that of conventional ones.The strips are characterized by brittle fracture,and the ductility is increased after modified by EP current.