采用光纤激光焊接工艺对表面涂覆不同配方活性剂的20Mn2钢管进行焊接, 通过光学显微镜、扫描电镜、能谱分析仪、显微硬度计及拉伸试验机等研究了活性剂配方对焊接接头显微组织与力学性能的影响。结果表明: 当涂敷活性剂后, 焊缝的熔深和熔宽均增加, 焊缝区晶粒均得以细化, 且均出现了氧和硅元素, 焊缝的硬度得以提高; 活性剂的最佳配方(质量分数)为36.36%SiO2, 36.36%TiO2, 9.10%Cr2O3, 18.18%NaF;涂覆该配方活性剂后, 焊接接头的抗拉强度和伸长率分别可达827.9 MPa和13.9%, 焊缝中心处的显微硬度比未涂敷活性剂的提高了21.8%。

Fluxes with different formula were coated on 20Mn2 steel pipes surface, and then the steel pipes were welded by fiber laser welding. The effects of flux formula on microstucture and mechanical properties of laser welded joint of 20Mn2 steels pipes by optical microscopy, scanning electron microscopy, energy disperse spectroscopy, micro-hardness tester and tensile tester. The results show that, after coating fluxes, the depth and width of weld seam both increased, grains in weld seam zone all were refined, O and Si elements were found in weld seam, and the hardness of weld seam increased. The optimum formula of the flux was 36.36wt%SiO2, 36.36wt%TiO2, 9.10wt%Cr2O3 and 18.18wt%NaF. When this flux was coated, tensile strength and elongation of the welded joint was respectively 827.9 MPa and 13.9%, microhardness of the weld seam center increased by 21.8% comparing with that of without coating flux.