高桂丽 缪神 蔡春波 张华军

摘 要：针对Q345B大厚板高强钢接头在机器人双面双弧焊中易出现焊不透、撞枪的问题，采用根部无预留间隙的焊接方法，通过增大焊接线能量、减小弧间距实现根部全熔透。依据《美国钢结构焊接规范》标准对接头进行力学性能试验和显微组织分析，结果表明：根部打底前焊道组织为针状铁素体和贝氏体，打底后焊道和填充焊组织为针状铁素体和少量的先共析铁素体；熔合区组织为针状铁素体和板条马氏体，粗晶区为板条束更粗大的板条马氏体。焊接接头平均抗拉强度达到536.47MPa，焊缝强度高于母材。接头出现局部硬化，硬度最高值为281HV，符合标准的要求。

关键词：Q345B大厚板；双面双弧焊；无预留间隙；机器人

DOI：10.15938/j.jhust.2018.04.021

中图分类号： TG444

文献标志码： A

文章编号： 1007-2683（2018）04-0113-05

Abstract：To solve the problem of incomplete penetration and the welding torch hitting the plate during the welding process of Q345B large thick plate by using robot doublesided arc welding， the method of using no reservedclearance root was proposed. The good forming weld joint was obtained by increasing the welding line energy and reducing the arc distance. The microstructure and mechanical properties of the welding joint were investigated according to the AWS D1.1. The results show that the first weld pass of root consists of acicular ferrite and bainite， and the second weld pass of root and filling pass consist of acicular ferrite and few of proeutectoid ferrite， and the microstructure of fusion region consists of acicular ferrite and lath martensite， and the coarse grain region consists of larger lath martensite . The average tensile strength of Welding joint reaches 536.47 MPa， and the tensile strength of welding is larger than fusion. Impact property of welding joint is good， and the highest hardness reaches 281HV.

Keywords：Q345B large thick plate； doublesided arc welding； no reserved clearance； robot

0 引 言

與传统大厚板人工焊接工序相比，焊接机器人具有高稳定性、高生产质量、高效率等优点[1-4]，特别是在大厚板焊接方面，具有焊接变形小、焊缝质量稳定、适用于大规模智能化生产的优点，且优化了焊接工艺，减少了焊前预热和根部清根的工序，大大节约了焊接时间[5-9]。但目前对于T型接头大厚板结构等大型构件，一般采用无钝边K型对称45°坡口，根部留有3-5mm间隙[10-13]，通过机器人示教或者离线编程和电弧跟踪相结合的方法进行双面双弧焊[14-16]。在焊接过程中由于焊缝收缩使原有根部间隙缩减为1-2mm，从而导致在初始的电流、电压下产生未焊透的现象。越靠近大厚板的根部焊道焊枪活动空间会极其狭小，如果焊接过程中机器人焊枪的角度不发生变化，由于焊缝收缩的影响极易发生碰壁、撞枪的现象，具有较大的安全隐患[17-20]。……