交变磁场下窄间隙GMAW焊接热源稳定性及焊缝成形调控机制研究

Electromagnetic arc oscillation narrow gap gas metal arc welding (NG-GMAW) can prevent insufficient sidewall fusion and it has been one of the potential joining technologies in thick plate welding, however, the bad stability of heat source and the poor controllability of the weld formation impede its development. In this project, the coupling interaction between welding arc, droplet and weld pool will be studied, based on which the mechanism of the heat source stability will be illustrated and a method controlling the weld pool behavior will be proposed. The above research results will be used to resolve the problems in electromagnetic arc oscillation NG-GMAW. The main research contents include: 1) studying the balance mechanism of heat force and proposing its stability conditions; developing the quantitative relationship between the characteristic parameters of magnetic field and the heat source stability; 2) developing a unified numerical model including the magnetic field，welding arc, droplet, weld pool, and analyzing their interaction; proposing a regulation method for weld pool behavior. The results can lay the foundation for solving the problems of the electromagnetic arc oscillation NG-GMAW in the thick plates, and promote its application in key equipment manufacture in the field of energy, defense and so on.

磁控摆动电弧窄间隙熔化极气体保护焊（NG-GMAW）能够克服常规NG-GMAW侧壁熔合不良焊接缺陷，是厚板构件连接领域极具发展潜力的关键技术之一，但成为主流技术前，仍存在焊接热源稳定性差、焊缝成形可控性低的难题。本项目通过研究焊接电弧、熔滴、熔池行为间的多场耦合关系，阐明焊接热源稳定机制及条件，掌握熔池行为的调控方法，解决上述难题。拟重点研究：1）摆动焊接电弧与熔滴过渡的综合热、力、电平衡机制，提出焊接热源稳定条件，构建焊接热源稳定性表征参量与交变磁场特征参数间定量关系；2）建立“磁场-焊接电弧-熔滴-熔池”的一体化多场耦合模型，分析其相互间的作用规律，提出熔池行为调控方法。研究结果为解决磁控摆动电弧NG-GMAW在厚板焊接领域应用中的关键难题奠定基础，推动其在能源及国防等领域重大装备制造中的应用。

厚板结构的连接技术对重大装备制造的质量、效率和安全具有关键影响。窄间隙焊接技术是厚板结构连接的重要技术之一，但是焊接过程中易出现侧壁熔合不良焊接缺陷，这严重影响焊缝质量及安全。磁控摆动电弧窄间隙焊接通过外加电磁力使焊接电弧偏向坡口侧壁，从而避免侧壁熔合不良焊接缺陷。但是目前对磁控摆动电弧窄间隙焊接机制仍缺乏研究。为此，本项目研究了磁控摆动焊接电弧的热力特性及其对熔池形成的影响，进而揭示磁控摆动电弧窄间隙焊接获得熔深均匀焊缝的机制。基于视觉检测及包含外磁场、焊接电弧、熔池及工件的一体化数值模型开展研究。结果表明，外磁场与焊接电弧自感应磁场叠加后，在综合电磁力作用下，焊接电弧偏向坡口侧壁。焊接电弧峰值温度基本不变，但与工件间的传导热及电子复合放热分布均由底面转移至侧壁，从而增大侧壁熔深。同时，焊接电弧的偏转使得熔池内形成有助于获得均匀熔深的流动模式。新的热流密度分布及熔池的流动模式是获得良好焊缝的根本原因。最后对外磁场参数及焊接工艺参数做了优化。本项目对磁控窄间隙焊接质量预测及工艺推广提供理论依据及基础数据。