超声辅助GTAW脉动电弧的物理特性及热力调控研究

Arc performance has direct and profound influence on welding quality, improving the conventional arc heat source to get efficient, high quality and controllable arc is an important research target. Combined with pre-research foundation, under concave spherical acoustic radiator condition, a novel arc source named ultrasonic assisted GTAW pulsated arc has been proposed in this project. The arc is contracted and there is a particle agglomeration inside the arc shaking up and down at a constant frequency under the action of the directional acoustic pressure from the surroundings to the arc center. The pulsated arc is regulated by applying the additional acoustic pressure field to improve the energy density and gradient of the welding heat source, optimize the energy distribution in the central area of the arc, control the thermodynamic transfer process and enhance the arc welding process. Mainly researches are as follows: 1) based on the arc information from the comprehensive observation and collection, this project will analyze the influence law of ultrasonic field on the behavior of pulsated arc, and then systematically study the physical characteristics of the pulsated arc. 2) Based on the acoustic propagation mechanism inside the arc, the mathematical model of the pulsated arc will be established to clarify the interaction mechanism between ultrasonic and arc plasma. 3) The energy transfer process of pulsated arc will be explored and the regulating method for adjusting the thermodynamic distribution of the pulsated arc will be set up to realize the control of the ultrasonic field to the thermodynamic distribution of pulsated arc on the side of the workpiece. This project can enrich the theory of welding arc under the action of ultrasonic field and provide new theoretical basis and technical support for deep digging the application potential of arc heat source.

电弧性能直接影响焊接质量，改进传统电弧热源，使其同时具备高效、优质、可控的属性一直是焊接研究目标之一。结合前期研究基础，本项目提出凹球面声发射端条件下超声辅助GTAW脉动电弧这一新型热源，利用由外向内指向性声压力压缩电弧，使电弧内部出现一高亮团聚区且以一定频率上下周期性抖动，拟通过声压场调控脉动电弧，增加电弧边界能量密度与梯度，优化电弧中心区能量分布，控制焊接热力传输过程，从而增强电弧焊工艺特性。具体研究内容如下：1）开展电弧信息综合采集实验，分析超声场对脉动电弧行为影响规律，研究脉动电弧物理特性；2）基于电弧等离子体内声传播机制，构建超声辅助脉动电弧数学模型，阐明超声与电弧等离子体交互影响；3）探究脉动电弧能量传递过程，建立超声辅助调控脉动电弧的方法，实现脉动电弧工件端热力分布的有效控制。本项目的研究可丰富超声场作用下的焊接电弧理论，对深入挖掘电弧热源应用潜力提供新的理论依据和技术支持。

以钨极氩弧焊（GTAW）为代表的传统电弧焊工艺因具有技术成熟、操作简便、易于实现自动化等优势，被广泛应用于各工业领域。然而，自由电弧热源存在着能量发散，焊接过程热力传输不易控制的问题，为此，本项目提出了超声辅助GTAW脉动电弧焊接方法，利用超声压缩作用，增大电弧热源边界能量梯度，提高电弧能量密度，调整电弧拘束度、高亮区体积大小及其上下抖动频率，控制热力输出大小和时间，利用声压场实现对脉动电弧热力的调控。基于试验与建模仿真分析，已经完成了奥氏体不锈钢及双相不锈钢等多种薄板材料的超声辅助GTAW脉动电弧焊接工艺研究。在316L奥氏体不锈钢焊接试验中，对比GTAW焊接，超声辅助GTAW脉动电弧在改善焊缝成形与提升性能方面效果较为显著，其焊接接头具有更大焊缝深宽比和等轴晶区面积，最大抗拉强度和延伸率分别提高了7.1%和26.2%，同时焊缝区具有更为良好的耐蚀性能。项目研究通过改进传统电弧热源，对于深入挖掘电弧热源的应用潜力，促进我国精密高效焊接制造技术的发展都具有重要的理论意义和工程应用价值。