旁轴式plasma-pulsed MIG复合焊电弧、熔滴、贯穿小孔和熔池的耦合机理

提高E36高强钢厚板的焊接效率和质量，可以降低豪华游轮的制造成本，提高我国船舶工业的竞争力。本项目采用旁轴式plasma-pulsed MIG复合焊来实现豪华游轮用E36高强钢厚板的高效高质量焊接。针对熔池中出现前壁非闭合贯穿小孔的情况，采用物理检测和虚拟仿真技术，研究电弧、熔滴、贯穿小孔和熔池的耦合机理，并提出有效的熔滴过渡和贯穿小孔控稳策略。基于高速摄影技术观测电弧形态和熔滴过渡行为，基于3D光谱诊断技术计算电弧等离子体温度和金属蒸汽分布，从而揭示前壁非闭合贯穿小孔对电弧耦合以及熔滴过渡的影响机制，最终实现稳定的“一脉一滴”熔滴过渡。构建新颖的熔池对流虚拟仿真模型，考虑前壁非闭合贯穿小孔对电弧热、力的影响，揭示前壁非闭合贯穿小孔对熔池传质、传热行为的影响机制。结合熔池虚拟仿真，小孔高速摄影和先进X射线检测，研究前壁非闭合贯穿小孔动态特性，揭示其保持动态稳定的内在机理。

Improving the welding efficiency and quality of thick E36 high-strength steel plates can reduce the manufacturing costs of luxury cruise ships and improve the competitiveness of our shipbuilding industry. In this project, a paraxial hybrid plasma-pulsed MIG welding process is adopted to join thick E36 high-strength steel plates used in luxury cruise ships with high efficiency and high quality. Advanced physical detection and numerical simulation technologies are used to study the coupled mechanisms of arc, droplet, penetrated keyhole and weld pool in this welding process in which the penetrated keyhole with an open front wall is formed. Effective control strategies of droplet transfer and penetrated keyhole stability are proposed. A high speed video camera is used to observe the arc shape and droplet transfer behavior, and an 3D spectroscopic technique is used to calculate the arc plasma temperature and metal vapor distributions; based on these results, the influence mechanisms of the penetrated keyhole with an open front wall on the arc characteristics and droplet transfer are revealed, and a stable “one pulse one droplet” transfer mode is reached. A novel weld pool model considering the influences of the penetrated keyhole with an open front wall on the arc heat and forces is developed, and the influence mechanisms of the penetrated keyhole with an open front wall on the heat and mass transfer inside the weld pool are revealed. Based on the weld pool simulation, the high speed video camera and advanced in-situ X-ray detection of the keyhole, the dynamic characteristics of the penetrated keyhole with an open front wall are investigated, and its internal mechanisms for maintaining dynamic stability are elucidated.