Porosity, incomplete fusion, and solidification cracks are frequently encountered defects in narrow gap laser welding. How to effectively inhibit welding defects while significantly improving welding efficiency has become the key technical challenge of narrow gap laser welding. In this paper, a new method of high-efficiency narrow gap dual-beam laser welding utilizing laser plume energy radiation to achieve "quasi-hot wire" filling is proposed. The solidification behavior of the molten pool was controlled by dual-beam to realize the reliable suppression of welding solidification cracks. The wire feeding speed and stability of the filler wire were improved by developing a high temperature resistant tungsten wire feeding nozzle. The "quasi-hot wire" filling was realized by the heating effect of laser plume energy radiation on the tungsten wire feeding nozzle. The wire feeding stability, thermal radiation characteristics, laser plume characteristics and weld formation during the welding process were studied. The high-efficiency welding of 120 mm high-strength steel was realized and the micro-structure and mechanical properties of the joints were tested and analyzed. The results showed that the method could effectively suppress the defects of porosity, incomplete fusion and solidification cracks in narrow gap laser welding. Compared with the traditional narrow gap laser welding (NGLW), the laser power was reduced by 10%. The welding speed was doubled, and the wire filling efficiency was increased by more than 1 time. The mechanical properties of the welded joint were comparable to those of the traditional narrow gap welded joints, which solved the prominent contradiction between the quality and efficiency of narrow gap laser welding of thick-wall components.

中文翻译：

---

120mm高强钢新型高效窄间隙激光焊接技术

气孔、未熔合和凝固裂纹是窄间隙激光焊接中经常遇到的缺陷。如何有效抑制焊接缺陷，同时显着提高焊接效率，成为窄间隙激光焊接的关键技术挑战。本文提出了一种利用激光羽流能量辐射实现“准热丝”填充的高效窄间隙双束激光焊接新方法。双束控制熔池凝固行为，实现焊接凝固裂纹的可靠抑制。通过开发耐高温钨丝送丝嘴，提高了填充焊丝的送丝速度和稳定性。通过激光羽流能量辐射对钨丝送丝嘴的加热作用，实现“准热丝”填充。研究了焊接过程中的送丝稳定性、热辐射特性、激光羽流特性以及焊缝成型情况。实现了120 mm高强钢的高效焊接，并对接头的显微组织和力学性能进行了测试和分析。结果表明，该方法能够有效抑制窄间隙激光焊接中的气孔、未熔合和凝固裂纹等缺陷。与传统窄间隙激光焊接（NGLW）相比，激光功率降低了10%。焊接速度提高一倍，焊丝填充效率提高一倍以上。焊接接头力学性能与传统窄间隙焊接接头相当，解决了厚壁构件窄间隙激光焊接质量与效率之间的突出矛盾。