摘要
为了研究15 mm厚316H不锈钢激光深熔焊接过程中气体保护模式对焊接过程的影响,建立了7种不同类型气体保护模式(A~G),并进行了焊接试验。借助可视化高速摄像观察焊接过程中的羽辉,利用焊道截面形貌表征不同气体保护模式对焊接过程中的羽辉的抑制作用。试验结果表明:侧吹保护气的加入对焊道截面形貌几乎没有影响,焊缝熔深、熔宽基本相同,但对类似激光束聚焦形态的狭长形羽辉有吹散作用,同时可以减少焊接过程中的飞溅现象。最终确定G类型气体保护模式(熔池保护气+横吹保护气+尾拖保护气+侧吹保护气)是激光深熔焊接过程中的最优气体模式。在G类型气体保护模式下,再次优化了激光功率、焊接速度、离焦量等关键焊接工艺参数,实现了316H不锈钢的单面焊双面成形,并分析了接头组织、冲击断口形貌、显微硬度等。结果显示,相关指标都在验收值以上,满足技术指标要求。研究结果为激光深熔焊接技术在316H不锈钢中厚板中的应用提供了参考。
Objective In the process of laser deep penetration welding,the laser beam interacts with the material to produce photo plasma,metal vapor,plume,and welding defects such as spatter and porosity.Among them,the root cause of small porosity is the instability of small holes,the collapse of the small hole,and the gas that enters the deep penetration welding hole is too late to escape during the solidification of the weld pool,which eventually affects the stability of the welding process.In order to study the influence of gas protection modes on the laser deep welding process of 15 mm thick 316H stainless steel and reduce the influence of photo plasma,metal vapor,plume,etc.,on the welding process,this paper carries out a study on the influence law of different types of gas protection modes on the laser deep penetration welding process.This paper provides a theoretical basis for the application of the laser deep penetration welding technology in 316H stainless steel plates.Methods First,the gas protection device is specially designed,and 5 gas channels are designed,namely molten pool protection gas(MP),transverse blowing protection gas 1(TB1),transverse blowing protection gas 2(TB2),side blowing protection gas(SB),and tail dragging protection gas(ST)(Fig.2).Second,seven different types of gas protection modes are established.Finally,the key process parameters such as laser power are kept unchanged,and only the gas mode is changed.The welding test is carried out successively from the gas protection mode A to G.Meanwhile,the images of plume and metal vapor in the welding process under different gas protection modes are observed with the help of visual highspeed photography(Fig.6).Furthermore,the crosssections of 7 beads are compared and analyzed,and the crosssectional morphologies of beads are indirectly used to characterize the suppression effect of different gas protection modes on the plume glow during welding.Results and Discussions The addition of SB has little effect on weld penetration depth and width.The crosssectional weld morphology of bead 7 is regular,the weld penetration depth reaches 10.1 mm,and the weld width reaches 2.5 mm(Fig.4).However,from the observation of highspeed photography,it is found that the addition of SB has a blowing effect on the narrow and long plume similar to the laser beam focusing shape,and can reduce the spatter during the welding process(Fig.6).Among them,the bead 6 has the worst shape(compared with the other 6 wbeads),especially irregular shape appears at the upper end of the weld,and it is tilted toward one side near the upper end of the weld.Combined with the gas mode F corresponding to bead 6,the interference of TB1(Ar)and TB2(Air)in this gas mode leads to drastic changes in the transient plume flow state,resulting in turbulence in the air flow near the weld pool.This results in poor deformation of the surface weld(Fig.4).Under the G type gas protection mode,key welding process parameters such as laser power,welding speed,and defocusing amount are optimized again,achieving doubleside formation from singlepass welding of 316H stainless steel(Fig.8).The microstructures of the base metal,weld metal,and heataffected zone are all austenitic metal.The lowest impact energy of a single sample is 198 J,which is far greater than the minimum 90 J requirement.There is a shear lip on the impact fracture of the weld,and obvious plastic deformation occurs.Conclusions The addition of SB has almost no effect on the crosssectional morphology of the bead,and the weld penetration depth and width are basically the same.However,from the observation of highspeed photography,it is found that the addition of SB has a blowing effect on the narrow plume similar to the laser beam focusing shape,and can reduce the splash during the welding process.Finally,it is determined that the gas protection mode of type G is the optimal gas configuration in the process of laser deep penetration welding.Under the G type gas protection mode,the key welding process parameters such as laser power,welding speed,and defocusing amount are further optimized to achieve doubleside formation from singlepass welding of 316H stainless steel.The weld forming is excellent,and the relevant indicators meet the technical requirements.The investigation here provides a theoretical basis and a practical experience for the application and development of laser deep penetration welding technology in 316H stainless steel medium plates.
作者
袁亮文
刘万存
赵佳
段莉蕾
Yuan Liangwen;Liu Wancun;Zhao Jia;Duan Lilei(Process Department,CFHI Dalian Nuclear Power and Petrochemical Co.,Ltd.,Dalian 116113,Liaoning,China)
出处
《中国激光》
北大核心
2025年第12期19-27,共9页
Chinese Journal of Lasers
基金
大连市科技人才创新项目(2024RY034)。
关键词
激光深熔焊
气体保护模式
羽辉
微观组织
力学性能
laser deep penetration welding
gas protection mode
plume
microstructure
mechanical properties
