退火对黄铜包覆纯铜绞线组织和力学性能的影响  

Effects of annealing on microstructure and mechanical properties of brass clad copper stranded wire

作　　者：雷宇 李永帅 姜雁斌 赵帆 刘新华 谢建新 LEI Yu;LI Yong-shuai;JIANG Yan-bin;ZHAO Fan;LIU Xin-hua;XIE Jian-xin(Key Laboratory for Advanced Materials Processing(MOE),Institute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China;Beijing Laboratory of Metallic Materials and Processing for Modern Transportation,Institute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China;Beijing Advanced Innovation Center for Materials Genome Engineering,Institute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China;School of Materials Science and Engineering,Central South University,Changsha 410083,China)

机构地区：[1]北京科技大学新材料技术研究院,材料先进制备技术教育部重点实验室,北京100083 [2]北京科技大学新材料技术研究院,现代交通金属材料与加工技术北京实验室,北京100083 [3]北京科技大学新材料技术研究院,北京材料基因工程高精尖创新中心,北京100083 [4]中南大学材料科学与工程学院,长沙410083

出　　处：《中国有色金属学报》2023年第3期702-714,共13页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(51925401)。

摘　　要：黄铜包覆纯铜绞线是电气化铁路综合接地系统的关键地线材料,目前主要采用套管拉拔法加工。本文采用连铸复合-拉拔加工新工艺制备了黄铜包覆纯铜绞线,研究了退火温度和时间对拉拔态复合线材微观组织、性能、界面和拉伸断裂行为的影响。结果表明:当退火时间固定为1 h时,随着退火温度的升高,纯铜芯线和黄铜包覆层再结晶程度增大,二者分别在275℃和300℃完成再结晶。在退火温度200~300℃、退火时间0.5~1 h的范围内,随退火温度升高和退火时间的延长,复合线材的硬度和抗拉强度快速下降,断后伸长率快速提高。随退火温度的提高和退火时间的延长,黄铜/纯铜界面的扩散层厚度增厚,从(250℃, 1 h)退火条件下的4.0μm增加至(400℃, 1 h)的7.2μm,或从(300℃, 0.5 h)时的4.3μm增加至(300℃, 2 h)时的8.1μm。综合考虑各种因素,推荐的合理退火条件为(300~350℃, 1 h)。在该条件下退火后,线材的断后伸长率由拉拔态的3%大幅度升高至约40%;黄铜包覆层的拉伸断裂模式由退火前的解理断裂转变为韧性断裂,有利于提升贯通地线的服役安全性和延长服役寿命。The brass clad copper stranded wire is the key material of the integrated grounding system of the electrified railway.In this paper,the brass clad copper stranded wires were prepared by a new process combined composite continuous casting and drawing,and the effects of annealing temperature and time on microstructure,properties,interface and tensile fracture behavior were studied.The results show that,when the annealing time is 1 h,the recrystallization degree of copper wire and brass cladding layer increases with the increase of annealing temperature,and the recrystallization is completed at 275℃and 300℃,respectively.In the annealing temperature range of 200−300℃and annealing time range of 0.5−1 h,with the increases of annealing temperature and time,the hardness and tensile strength of composite wires decrease significantly,and the elongation increases significantly.With the increases of annealing temperature and time,the thickness of diffusion layer increases from 4.0μm at(250℃,1 h)to 7.2μm at(400℃,1 h),or from 4.3μm at(300℃,0.5 h)to 8.1μm at(300℃,2 h).The optimized annealing condition is 300−350℃for 1 h.Under this condition,the elongation after fracture increases from 3%to about 40%,and the tensile fracture mode of brass cladding layer changes from cleavage fracture to ductile fracture,which is beneficial to improve the service safety and life of the grounding wire.

关 键 词：贯通地线 复合线材 退火 组织性能 界面 断裂行为 

分 类 号：TB331[一般工业技术—材料科学与工程]