摘   要激光＋MIG复合焊接综合了激光焊和MIG焊的优点，使其成为现代工业钢板高效焊接最有潜力的方法之一。本文使用激光＋MIG电弧复合焊接系统对8mm 厚钢板T型接头进行了焊接，研究了激光功率、焊接电流、激光光斑距翼板距离、激光入射角度及焊接速度对T型接头焊缝成形的影响，优化了焊接工艺，最终采用优化后的参数进行了焊接，焊后对T型接头不同部位的微观组织进行了观察和分析，并测试了接头不同部位的显微硬度。试验结果表明：86170

激光+MIG复合焊在较高焊速（0。6m/min～0。9m/min）条件下均可得到成形连续、无裂纹、气孔等缺陷的T型接头，与传统的MIG焊相比，焊后变形小，生产效率大大提高；通过工艺试验可知激光功率、焊接电流、焊接速度、激光入射角度及激光光斑距翼板的距离对T型接头焊缝的成形都有显著影响；采用优化的焊接工艺参数，即激光功率4kW，焊接电流200A，焊接速度0。9m/min，激光入射角度8°，激光光斑距翼板的距离0。5mm，光丝间距2mm，可以得到成形美观，无焊接缺陷、焊缝质量优良的T型接头。

由微观组织分析得出T型接头焊缝的热影响区由熔合区、过热区、相变重结晶区以及不完全重结晶区组成，焊缝晶粒主要由珠光体组织和铁素体组织，还有少量魏氏体组织。T型接头焊缝显微硬度比母材显著提高。

关键词:T 型接头；激光复合焊；焊接工艺；微观组织；显微硬度

Abstract

Laser + MIG hybrid welding combined the advantages of laser welding and MIG welding, which maked it become one of the most promising methods for high efficiency welding in the steel plate of modern industrial。 In this paper, welded the 8mm thick steel plates of T-joint by laser + MIG arc hybrid welding system。 The effects of laser power，welding current, distance from the floor plate of the laser spot, incident angle of laser beam and welding speed on the weld formation of T-joint were studied。 Optimized the welding process, Finally, the optimized parameters were used for welding。 The test results showed:

 When the welding speed (0。6m / min ~ 0。9m / min) reached high-speed welding by laser + MIG hybrid welding, got continuous, smooth, beautiful shape, no cracks, holes and other defects etc, T-joint deformation was small。 Compared with the conventional of MIG welding, Laser+MIG hybrid welding greatly improved production efficiency; The results showed that laser power, welding current, distance from the floor plate of the laser spot, incident angle of laser beam and welding speed haved a significant effect on the weld of T- joint。 By process test showed that haved a significant impact from the laser power, welding current, welding speed of the laser incident angle of the laser spot from the wing and T-joint welds forming; The optimized welding technology was used to obtain the T-joint which was without welding defect and beautiful appearance。 Obtained the process parameters of the optimal laser +MIG hybrid welding。 laser power is 4kW, the welding current is 200A, the welding speed was 0。6m / min, the laser incident of angle was 8°, the floor plate of the laser spot of distance was 0。5mm, optical fiber spacing was 2mm。 T-joint has the good weld shape, which could be to maximize the reduction of the bottom plate and the edge of the edge of the plate, the welding of deformation was small, the quality of T-joint was good。 

The heat affected zone of the weld joint of T-joint was formed by the fusion zone,  the overheated zone, the phase change recrystallization region and the incomplete recrystallization region through the analysis of microstructure。 The grain of the weld was mainly composed of Pearlite and Ferrite, in addition to a small amount of Widmanstatten structure。 The microhardness of the weld T- joint was significantly higher than that of base metal。