Effect Of Heat Treatment Process On Precipitates And Property Of Aluminum Alloy Electrical Round Rod

With the continuous progress of science and technology,almost all industries for the power demand is gradually increasing,the development of the power industry is also changing.However,the early transmission of aluminum wire has been far from being able to meet the requirements of large load transmission.Therefore,the transmission line to high pressure,large capacity and long distance and other direction of the development is extremely urgent.Aluminum wire is made up of the casting electric aluminum ingot by continuous casting and rolling.As the manufacture of semi-finished aluminum wire,the quality of aluminum electric round rod directly affects the quality of aluminum wire.In this paper,the composition of the sample was optimized at the early stage of our research group.The research object of experiments is Al electrical round aluminum rod boronized with 0.02% B.The experiment was carried out by testing the tensile strength and electrical conductivity of samples.Moreover,the methods of OM,SEM,TEM,EDS and XRD were used to analyze microstructure and phase composition of the specimen.Firstly,the effects of single-stage homogenization under different temperature and time on the microstructure and properties of aluminum alloy electric rods were investigated.On the basis of the better single-stage homogenization process was determined,the effect of different temperature and time two-stage homogenization on the microstructure and properties of aluminum alloy electric rod was studied,aiming to obtain better two-stage homogenization process.Secondly,the aluminum alloy electric round rods were treated with different temperature and different quenching medium(water,oil and PAG),and their effects on the microstructure and properties of aluminum rods were also discussed.The better solution was obtained by comparative analysis of the results.In addition,the effect of different pre-deformation and pre-aging temperature on the precipitates and properties of aluminum rods was studied,expecting to obtain aluminum electric round rods withexcellent comprehensive performance.The research results were shown as follow.(1)After homogenization treatment,the organization of sample was more uniform,and the grain boundary was purified greatly.The precipitated phase was in the form of granules and strips and uniformly dispersed on the aluminum matrix.The grain size of aluminum alloy round rod was not obvious When the sample was homogenized at440? for 3h,the comprehensive performance of aluminum electric round rod was better,the electrical conductivity was reach to 57.67%IACS,the tensile strength was100 MPa.When the two-stage homogenization process was 410?×2h + 425?×1h,the tensile strength and electrical conductivity of the sample were better,the tensile strength was 102 MPa,the electrical conductivity was 57.96%IACS.The rolling treatment was conducted on the specimens with better comprehensive performance,when the deformation was 83%,the tensile strength,electrical conductivity and elongation of specimen was 178 MPa,57.06% IACS and 10%,respectively.(2)After solid progressive solution + 13% PAG quenching treatment,the alloying elements of samples were more fully dissolved in the aluminum matrix,and almost no particles were precipitated in the matrix.Only a very small amount of particles were precipitated at the grain boundary.When the progressive solution treatment of sample was 350?×1h + 510?×6h,and cooled in a concentration of 13% polyaleneglycol(PAG)medium,the sample had better comprehensive performance,the conductivity of the samples was about 56.6% IACS,and the tensile strength was 103 MPa.(3)The two-stage deforming aging process was conducted on the specimens with better progressive solution treatment.After two-stage deformation aging treatment,the grain size of the sample was refined and the structure was uniform.Moreover,the dislocation density of the specimen increased greatly,and the dislocations were intertwined with each other.The precipitates increased obviously,these phases may be Al0.3Fe3Si0.7?Fe3Si?CeCu6,etc.,most of the precipitates were granular,a small part of the rod-like,which distributed uniformly both in the grain boundary and the grain interior.When the pre-deformation was 11% and the pre-aging was treated at 130?,the comprehensive performance of the samples was better.The electrical conductivity was 58.5%IACS,tensile strength was 181 MPa,and elongation can reach to 8%.Theelectrical conductivity and tensile strength of the aluminum alloy electric round rod were improved obviously.