Preparation And Study Of Properties Of Moderate Strength And High Conductivity Aluminum Alloy Wire

Al-Mg-Si alloy has been widely used in long distance and large span transmission lines because of its good mechanical properties,conductivity,plastic formability and corrosion resistance.In order to meet the needs of the transformation of transmission line capacity,a new moderate strength and high conductivity Aluminum alloy conductor material is developed,which ensures the strength of the alloy and simultaneouslyfurtherenhances the conductivity of the material.The conductor materialis used in the manufacture of moderate strength full Aluminum alloy strand.In this paper,the Al-Mg-Si alloy conductor material for overhead bare wire wereobject of study.Alloy composition were designed by adjusting Mg,Si,mixed rare earth and B alloying treatment.The comprehensive analysis were conducted on the microstructure and properties of the alloy under different processing conditions,which determined the optimal composition of Al-Mg-Si-RE-B alloy.The as cast microstructure,the rare earth phase and the non-equilibrium phase of the optimal Al-Mg-Si-RE-B alloy were discussed deeply.The influence of different processing technology,homogenization and aging treatment on the microstructure and properties of the optimal alloy werein detail investigated.The high-performance moderate strengthand high conductivity Al-Mg-Si-RE-B alloy wire wereobtained.The main results are as follows:1.By means of the comparison of the tensile strength,conductivity and elongation of the four alloys under T8 condition,the optimal Al-Mg-Si-RE-B alloy is Al-0.32Mg-0.42Si-0.2RE-0.08 B,and the tensile strength,conductivity and elongation of the alloy wireare246.67MPa?60.12%IACSand 6.9%.The tensile strength and conductivity of the optimal alloy in cast state are105.0MPaand 56.42%IACS.2.The rare earth element in the as cast microstructure of the optimal alloy is enriched in the vicinity of the long ?(Al-Fe-Si)phase to form a spherical Al-Si-(La/Ce)phase containing no Fe element.Rare earth and B interact to form Al-B-(La/Ce)phase.The non-equilibrium phase is mainly Al-Fe-Si three eutectic phase,in which there isa lot of stripe like or fish squamous ?(Al-Fe-Si)phase.3.With the increase of the temperature(540??560??580?)and the extension of the holding time(6h/7h/8h/9h),the hardness of the alloy decreases and the conductivity of the alloy increases.Finally,the hardness and the conductivity tend to be stable.By comparing the microstructure,electrical conductivity and hardness of the alloy,the optimum homogenization technology is homogenizing at 570°C for 8 hours,and the conductivity is 57.12%IACS.4.The tensile strength of Al-0.32Mg-0.42Si-0.2RE-0.08 B alloy wire increases first and then decreases with the extension of aging time at 150?,170? and 190? aging.With the increase of aging temperature,the time at which the tensile strength reaches the peak is less.The higher the aging temperature,the higher the peak strength is not necessarily higher.The conductivity of Al-0.32Mg-0.42Si-0.2RE-0.08 B alloy wire increases with the extension of aging time,and finally tends to be stable at 150?,170?,190?and 210? aging,but the increasing rate of the conductivity is quite different.When the aging time is the same,the higher the temperature is,the higher the conductivity is.5.Considering the design principle of the wireand the influence of the aging temperature,the aging timeand et al.on the properties of aluminum alloy wire,the reasonable aging treatment process of the Al-0.32Mg-0.42Si-0.2RE-0.08Bmedium-strength aluminum alloy wireis aging at 190? for 9h.The tensile strength,conductivity and elongation of moderate strength and high conductivityAluminum alloy wire are 241.82MPa?60.24%IACSand 6.2% under the reasonable aging treatment.