拉拔变形对不同直径纯铜线材组织性能的影响

Effects of Drawing Deformation on Microstructures and Properties of Pure Copper Wires with Different Diameters

将初始直径为φ7 mm、φ5 mm、φ3 mm的纯铜线材分别进行冷拉拔,得到不同变形量的试样,测试了试样的硬度和导电率,研究了冷拉拔变形量对不同初始直径纯铜线材组织和性能的影响。研究结果表明:拉拔变形对不同初始直径线材硬度和导电率的影响趋势大体一致,当变形量小于30%时,硬度快速上升,导电率快速下降;当变形量为30%～83%时,硬度缓慢上升,导电率变化不大;当变形量大于83%时,导电率和硬度都出现了波动。φ7 mm线材在变形量为83%时,硬度最高可达121HV,此时导电率为98%IACS;φ5 mm线材在变形量为75%时,硬度最高可达122HV,此时导电率为97%IACS;φ3 mm线材在变形量为83%时,硬度最高可达128HV,此时导电率为97%IACS。微观组织观察表明:纯铜的组织演化分为3个阶段,晶粒开始分裂并出现形变孪晶;分裂加剧,晶界消失;形成纤维组织。

Three types of pure copper wires with initial diameters φ7 mm,φ5 mm and φ3 mm were drawn respectively.The hardness and electrical conductivity of the samples of different deformation were measured and the microstructures were observed.The effects of cold drawing deformation on microstructures and properties of pure copper wires of different initial diameters were studied.The results show that the effects of deformation on hardness and electrical conductivity of wires of different initial diameters are almost the same.When the deformation is less than 30%,the hardness is increased rapidly and the electrical conductivity is decreased rapidly.When the deformation is between 30% and 83%,the hardness is increased slowly,and the electrical conductivity changes unobviously.When the deformation is more than 83%,both of the hardness and electrical conductivity appear fluctuation.When the deformation is more than 83%,the highest hardness of the φ7 mm is 121HV,and the electrical conductivity is 98% IACS.When the deformation is 75%,the highest hardness of the φ5 mm is 122HV,and the electrical conductivity is 97% IACS.When the deformation is 83%,the highest hardness of the φ3 mm is 128HV,and the electrical conductivity is 97% IACS.The microstructures revealed that the microstructure evolution of pure copper is divided into three phases.The grain begins to split and deformation twins are observed.The grain split increases and the grain boundary becomes obscure.The fiber texture is observed.