以高强钢为试验材料，采用CO2激光-熔化极活性气体保护焊(Metal active gas arc welding，MAG)复合焊接方法，研究原位内生TiC对高强钢焊接接头组织和性能的影响。研究结果表明：原位内生TiC颗粒能够细化焊缝组织，对高强钢焊接接头的综合性能有很大的提高，其中wCNT∶wTi=15%的焊缝上部中心区主要由树枝晶组成，二次枝晶平均宽度为8.4 m。焊缝下部主要由大量的等轴晶组成。而未加粉焊缝上部中心区主要由大量柱状晶组成，柱状晶平均宽度为13.25 m焊缝下部主要由大量细小柱状晶组成。通过断口分析知，wCNT∶wTi=15%焊缝处的断口处产生大量细小韧窝，焊接接头主要是韧性断裂，而未加粉的焊接接头主要是脆性+韧性断裂。通过力学性能测试知，原位内生TiC对高强钢激光-电弧复合焊接接头的冲击吸收能量、弯曲能量度及硬度都有明显提高，但是对抗拉强度影响不大。

A CO2 laser-metal active gas arc welding(MAG) hybrid welding technology is used to weld the high strength steel. The effects of in situ TiC on microstructure and properties of welded joints are investigated. Results indicate that microstructure can be refined by TiC particles. The overall performance of high strength steel welded joints has been greatly improved. When the wCNT∶wTi=15%, the upper center part of the weld is composed mainly by dendrites. The average width of secondary dendrite is 8.4 m. The bottom of weld is composed mainly by large numbers of small equiaxed. When the wCNT∶wTi=0%, the upper center part of weld is mainly composed by large numbers of columnar grains. The average width of the columnar crystal is 13.25 m. The bottom of weld is mainly composed by large numbers of small columnar grains. The study on fracture shown that, there have been a large amount of small dimples in the wCNT∶wTi=15%. It is mainly ductile fracture for welded joint. But it is mainly brittle fracture and ductile fracture for welded joint of no powder. Known by the mechanical testing that the impact of energy and bending energy have been significantly improved for the weld of high strength steel in situ TiC, but it has little effect on tensile strength.