中文摘要：

采用焊剂带约束电弧超窄间隙焊接方法对U71Mn钢轨对接进行试验研究。结果表明，焊前坡口底部间隙宽度预留为4．5mm反变形角度设定为1.3°，焊接过程中对钢轨进行定位，可保证每层坡口间隙宽度稳定的保持在4～5mm之间，通过48层焊道可完成对钢轨的超窄间隙焊接。采用此种方法焊接时．使用H08Mn2Si焊丝，焊剂中不添加任何合金元素就能够获得焊缝区硬度与母材相当、热影响区硬度高于母材的接头，焊缝区组织为铁素体和珠光体，热影响区组织为晶粒较细小的片状珠光体。得到的接头冲击功远大于要求的6J。

英文摘要：

Utilized ultra-narrow gap welding with constrained arc by flux band to make experimental study on U71Mn rail welding.The results showed that, before welding the bottom gap width was reserved 4.Smm,anti-deformation angle was set to 1.3~ and positioned the rail when welding,which could maintain the gap width of each layer weld bead between 4mm and 5mm,through 48 layers of bead could complete the entire rail ultra-narrow gap welding. When utilized this method of welding, using H08Mn2Si wire, flux didn＇t add any alloying elements could obtain the joint, which the hardness of the base metal and weld zone equivalent, and heat affected zone was harder than the base metal, the weld area was acicular ferrite, heat affected zone was finer grain size of the lamellar pearlite.And the impact energy of joint was much larger than requirements 6J.