热镀锌板电阻点焊焊缝折弯开裂分析  

Cracking analysis of bending electric resistance weld seam for galvanized steel sheet

作　　者：张彦文[1] 吴立新[1] 陈宇[1] 许竹桃[1] 

机构地区：[1]武钢研究院,武汉市430080

出　　处：《焊接》2014年第11期52-54,70,共3页Welding & Joining

摘　　要：热镀锌板搭接电阻点焊焊缝在折弯成形时出现开裂。为了弄清开裂原因,运用宏观观察、扫描电镜及能谱仪、光学显微镜等方法进行了分析,结果表明:电极经过一段时间使用后,在较高温度下,由于镀层与电极之间的扩散,红铜电极逐渐变为黄铜,导电性及导热性能下降,电极表面接触电阻增大,焊接时接触部位产生的电阻热也随焊接次数增多而逐渐增加;最终导致焊接时Cu,Zn元素扩散至基板晶界,使基板变脆。在受外力作用时,基板沿晶界开裂。Cracking occurs when weld seams of electric resistance welding for galvanized steel sheet were bent.In order to find how it occurred,the cracked weld seams are analyzed by macroscopical observation,scanning electron microscope and microscope.It shows that the copper electrode changes gradually into brass electrode after being used at high temperature for some times because of the diffusion between zinc coating and copper electrode end,so its thermal conductivity and electric conductivity decrease,the contact resistance increase and the resistance heat also increase at the contact zone of electrode and zinc coating.At last,Cu and Zn diffuse to the grain boundary of base metal which makes the base metal brittle.The base metal cracks along grain boundary when it was bended.

关 键 词：热镀锌板 电阻点焊 电极 沿晶开裂 

分 类 号：TG113.263[金属学及工艺—物理冶金]