基于激光-磁场协同调控电弧的厚板窄间隙弧焊机理

Narrow gap arc welding is a very critical technology for thick plate connecting. But the weld arc is easy to lose its stability and/or lack of spread to result in sidewall and interlayer non-fusion defects. The previous solutions, including attacking auxiliary mechanism, using combined heat source, or adapting groove geometry, could partly improve the fusion capability. However, such solutions could not fundamentally control the arc stability and spreadability which make it impossible to completely avoid sidewall and interlayer non-fusion defects. Also, high speed narrow gap welding is only theoretical possible. To improve the fusion effect during narrow-gap welding, the arc welding based on combined laser-magnetic energy fields is proposed in this project. By synergies of laser stabling arc effect and magnetic controlling arc effect, the narrow gap arc welding based on combined laser-magnetic energy fields could completely avoid sidewall and interlayer non-fusion defects as well as improve welding speed. Firstly, force analysis model of electric charge at arc zone is constructed to investigate the reason for arc geometry change. Secondly, the influence of combined laser-magnetic field on arc stability and spreadability is discussed. At last, the critical process conditions to make sure the weld bead to be well connected and processing window during high speed thick plate narrow gap welding are established. The significance of this project is to propose a new method for thick plate narrow gap welding. Once its related mechanism and key technology are got breakthrough, it will significantly promote the application of narrow-gap welding for large-scale ultra-thick component.

窄间隙弧焊是一种重要的厚板焊接方法，但电弧在窄间隙条件下易失稳或铺展性不良，而导致侧壁及层间未熔合等严重质量问题，更无法实现高速焊接。虽然采用辅助机械装置、复合热源、优化坡口等手段，可以改善熔合效果，但由于无法从根本上对电弧进行调控，实际应用效果还有待提高。本项目提出一种基于光-磁协同控弧的厚板窄间隙弧焊新方法，该方法通过激光稳弧、磁场控弧等协同作用，有效调控电弧稳定性和铺展性，彻底解决内部熔合不良和焊接速度低下等问题。项目首先探究电弧电荷在激光-磁场协同作用下的运动规律，进而探索激光-磁场对电弧稳定性、铺展性的调控机制，在此基础上，建立厚板窄间隙侧壁和层间熔合良好的临界工艺条件及高速焊接工艺窗口。本项目研究意义在于，提出了一种极有前途的厚板窄间隙焊接新方法，该方法可有效抑制接头内部未熔合等缺陷、均匀焊缝组织并提高焊接速度，其核心机理一旦突破，将使得超大厚度构件的焊接技术获得跨越式发展。

窄间隙弧焊是一种重要的厚板焊接方法，但电弧在窄间隙条件下易失稳或铺展性不良，而导致侧壁及层间未熔合等严重质量问题，更无法实现高速焊接。虽然采用辅助机械装置、复合热源、优化坡口等手段，可以改善熔合效果，但由于无法从根本上对电弧进行调控，实际应用效果还有待提高。本项目提出一种基于光-磁协同控弧的厚板窄间隙弧焊新方法，该方法通过激光稳弧、磁场控弧等协同作用，有效调控电弧稳定性和铺展性，彻底解决内部熔合不良和焊接速度低下等问题。针对研究内容一（激光-磁场协同作用下电弧电荷受力分析及运动过程）：建立了考虑光致等离子体及磁场力影响的电弧电荷受力模型，分析了等离子体流力、洛伦兹力、电场力对电荷加速度的影响，揭示了电弧不同区域中电荷速度及加速度变化规律，描绘出电弧轴线及边缘等典型位置电荷运动过程，阐明激光-磁场外加能场改变电弧形位及方向的原因。针对研究内容二（激光-磁场对电弧稳定性、铺展性的调控机制）：建立了耦合激光-磁场作用的电弧形位模型，分析了激光扫略轨迹对电弧稳定性的影响，分析不同磁场形式对窄间隙电弧形位的影响，评估了窄间隙下激光-磁场协同作用的控弧效果。在不同的激光-磁场参数下，研究316L不锈钢板窄间隙焊接条件下电弧的形态稳定性和接头外观成形缺陷的情况，阐明激光-磁场对窄间隙弧焊过程的调控机制。针对研究内容三（厚板窄间隙条件下侧壁和层间熔合良好的临界工艺条件以及厚板窄间隙高速焊接工艺窗口）：确立激光-磁场联合作用下的电弧临界形位条件，探究焊接速度同电弧形位的相关性规律，建立厚板窄间隙高速弧焊工艺窗口，开展焊接接头组织及性能不均匀性研究。基于不同磁场下的焊缝成形、微观组织和力学性能，阐明激光-磁场对316L奥氏体不锈钢窄间隙弧焊接头的形性调控机制。.基于上述研究工作，发表论文23篇，其中SCI收录20篇；申请并获授权发明专利3项；培养/协助培养硕士研究生4人。