VacuumbrazingofcoppertubesusingAgCufiller.docVIP

Vacuum brazing of copper tubes using Ag-Cu filler LI Ruifenga, SHI Zhongxingb, QI Kaic and WU Mingfangd Provincial key Lab of Advanced Welding Technology, School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang Jiangsu 212003, P. R. China ali_ruifeng@, bszx8460561@126.com, cqikailx@163.com Keywords: Copper tubes; Vacuum brazing; Microstructure; Ag-Cu filler Abstract. Joining of copper tubes using Ag-Cu filler has been carried out by vacuum brazing technology. The microstructure and mechanical property of brazed joints were studied by means of metallography, optical microscope(OM) and universal tensile test machine. Experimental results show that failure occurs in the base metal and the tensile strength can reach 179 MPa. The optimal vacuum brazing parameters are: brazing temperature 810 oC, vacuum level 10-3Pa and holding time 3 min. Introduction The copper tubes are wildly used in different environments for it has a high hardness, good thermal conductivity, and resistance to high temperature, high pressure, and corrosion[1,3]. Galvanized steel tubes, were widely used in our home in the past as water tubes, were easy rust, turn the water yellow and reduce the water flow. Copper tubes are hard and have a good capacity of corrosion resisting, which can easy resolve these problems[4]. Hot water tubes are made of some other materials will reduce its strength quickly under the high temperature condition, becoming a hiding trouble. The high melting point of copper makes it safe enough to be used as the material of hot water tube[5]. The increasing use of copper tubes makes people pay more and more attention to the welding process and welding quality[5]. In vacuum brazing, resistance-heated furnace can ensure the whole part were heated uniformly and heat different seam at the same time[6]. It can decrease welding distortion and control the brazing temperature to avoid overheating[7,8]. The vacuum will protect the part from bei