Balanced 6061 Aluminum Alloy Enhancement Study

6xxx series aluminum alloy is Al-Mg-Si series alloy,which belongs to typical heattreatable strengthening alloy,and is the most important pressure-processed alloy in wrought aluminum alloy.A 6061 aluminium alloy conductor is a medium to high strength conductor.Due to its high conductivity,specific strength,good corrosion resistance and long service life,6061 aluminium alloy conductors are widely used in extruded conductors for overhead transmission lines and other applications.With the overall development of the power industry,the performance requirements of aluminum alloy conductors are gradually raised.Therefore,this paper explores the best 6061 aluminium alloy strengthening methods by means of alloying and artificial aging heat treatment,the optimum addition amount of alloying elements and the optimum aging process were obtained,the factors affecting the activation energy of alloy precipitation were investigated,and the kinetic model of precipitation strengthening phase was established,the effect of aging temperature and time on the properties of the alloy is predicted.Cu(ω=0.4%,0.6%,0.8%,1.0%)was added into Al-Mg-Si alloy,and the electrical conductivity,mechanical properties and microstructure of the alloy with various compositions were measured,it was found that the tensile strength,yield strength and electrical conductivity of the alloy with ω=0.8%Cu were 404.2MPa,343.9 MPa and 47.4%IACS,respectively,after solid solution treatment at 550℃ for 1 hour and artificial aging treatment at 175℃ for 16 hours,the comprehensive electrical conductivity and mechanical properties are the highest.It is found that the addition of Cu can significantly refine the β" phase,increase the number of precipitates and increase the density of precipitates.The relationship between the volume fraction of the second phase and the resistivity and yield strength is derived from Mattiessen’s law and the dislocation cut-through mechanism,based on the JMA equation,the apparent activation energies of the main precipitated strengthening phases of 0.3 Cu alloy were calculated by linear fitting of the yield strength and resistivity measurements,98.9 kJ/mol and 105.7 kJ/mol,respectively.It is concluded that the main precipitated strengthening phases in this study are GP region and β" phase.The activation energy of the alloy containing 0.8 Cu is 75.8 kJ/mol calculated by linear fitting of the measured values of yield strength and 77.8 kJ/mol calculated by the measured values of resistivity,the addition of Cu can decrease the precipitation activation energy of β" phase,promote the transformation of GP region to β"phase,increase the nucleation particles of β" phase,and make the β" phase become coMPact,thus increasing the strength of the alloy.Based on the previous work and error analysis,the formula of the relationship between yield strength and aging time and aging temperature of 0.3 Cu alloy is derived,the validation experiment of aging time is 2 hours and aging temperature is 190℃,which proves the prediction accuracy of the relation formula.