摘要
采用同轴的脉冲和连续双激光为焊接热源,提出了钒(V)中间层协助CuSi3Mn1焊丝的TC4/QP980异种金属焊接方法。分析了0、0.05、0.10和0.15 mm厚度的V层对接头焊缝成形、微观组织以及力学性能的影响规律。结果表明,V中间层配合双激光填丝焊接工艺可以提高焊接过程的稳定性,焊缝表面平整,接头力学性能明显提高。当V中间层厚度为0.10 mm时,接头力学性能最优,达到了457 N/mm。无V中间层的TC4侧界面微观组织结构为α-Ti/TiCu/Ti_(5)Si_(3)/α-Cu。V中间层优化后的界面微观组织分为两层:上层为α-Cu/(Fe,V,Cu,Si)固溶体/V,下层为V/(Ti,V)固溶体+Ti_(2)Cu/Ti_(2)Cu+TiCu/(Ti,Cu)固溶体+Ti_(2)Cu/α-Ti。V中间层配合双激光填丝焊接工艺有效抑制了脆性金属间化合物的生成,优化了界面结构,显著提高了焊接接头的力学性能。
Objective The joining components of titanium alloy and steel have been widely used in aerospace,automobile manufacturing and other fields because of their high strength and light weight.However,the formation of TiFe intermetallic compounds seriously affects the mechanical properties of joints welded with titanium alloy and steel dissimilar metals,which limits their further application.The selection of appropriate welding methods and the use of the interlayer or filler materials are of great significance for obtaining efficient and reliable titanium alloy/steel joints.Dualbeam laser welding can accurately control the composition of intermetallic compounds in dissimilar metal welding,and is more stable than single laser welding.The use of single interlayer or filler material can inhibit the formation of TiFe intermetallic compounds,but other intermetallic compounds might be formed.Therefore,in this study,the dualbeam laser welding method is used and V is added as an interlayer on the basis of using CuSi3Mn1 filler wire to optimize the interface structure of the joint and improve the mechanical properties of the joint.Methods TC4 titanium alloy and QP980 highstrength steel are used as the base materials,and CuSi3Mn1 alloy is used as filler wire.A novel welding method with coaxial pulsedcontinuous dualbeam laser heat source assisted by V interlayer is adopted.The microstructure and mechanical properties of the joints with different V interlayer thicknesses are compared.The macroscopic morphology of the joint is observed by optical microscope,and the mechanical properties are tested by universal tensile testing machine.The element distribution and phase composition of the interface microstructure of TC4/QP980 joints with and without V interlayer are tested and analyzed by electron probe Xray microanalyzer.Results and Discussions The V interlayerassisted dualbeam laser welding process can obtain TC4/QP980 welded joints with smooth weld surface and high strength.When the thickness of the intermediate layer is small,the high energy heat input of the dualbeam laser destroys the V interlayer,resulting in a large influx of CuSi3Mn1 filler wire and forming a thick intermetallic compound reaction layer between the V interlayer and TC4.In contrast,when the thickness is large,there are pores and incomplete welding(Fig.2).The joints with a 0.10 mmthick V interlayer have the better mechanical properties,and the maximum tensile shear load reaches 457 N/mm(Fig.3).The steelside interfaces are all composed of Fe solid solution(ss)+Cu solid solution(Figs.4 and 5).However,the microstructures of the TC4-side interfaces are different.TC4-side interface without V interlayer is mainly composed of TiCu and Ti_(5)Si_(3)intermetallic compounds with large hardness and brittleness,and the thickness of the intermetallic compounds layer is about 200μm(Fig.6).The microstructure of the TC4-side interface using V interlayer is optimized to two layers,and the total thickness is reduced to about 110μm(Fig.7).The upper layer is composed ofαCu/(Fe,V,Cu,Si)ss/V,and the thicknesses of the ss layers are less than 2μm.The microstructure of the lower layer is V/(Ti,V)ss+Ti_(2)Cu/Ti_(2)Cu+TiCu/(Ti,Cu)ss+Ti_(2)Cu/αTi.The formation of Ti_(2)Cu,which has lower brittleness than TiCu,and the solution bonding both improve the bonding strength of the TC4-side interface.Conclusions In this study,a novel welding method with coaxial pulsedcontinuous dualbeam laser heat source assisted by V interlayer is proposed.The main problem of TC4 titanium alloy and QP980 highstrength steel welding is that it is easy to form TiFe intermetallic compounds between them,which leads to stress concentration and finally the joints fracture.The thickness of the V interlayer is adjusted to match the dualbeam laser welding process.The maximum tensile properties can be obtained when the thickness of the V layer is 0.10 mm.The application of a V interlayer can improve the interface microstructure and reduce the thickness of the bonding layer to about 100μm.Overall,the proposed coaxial pulsedcontinuous dualbeam laser welding method assisted by V interlayer can effectively suppress the formation and thickness of intermetallic compounds in TC4 and QP980 highstrength steel welded joints,optimize the interface microstructure,and thus improve the mechanical properties of welded joints.This study provides a new theoretical support for solving the problem of dissimilar metal welding of titanium alloy and steel,and a reference for the application of dualbeam laser welding technology in highperformance dissimilar metal structures.
作者
李楠
王德喜
汤雅雯
张菡轩
王红阳
刘黎明
Li Nan;Wang Dexi;Tang Yawen;Zhang Hanxuan;Wang Hongyang;Liu Liming(Liaoning Province Key Laboratory of Advanced Joining Technology,School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China)
出处
《中国激光》
北大核心
2025年第12期1-9,共9页
Chinese Journal of Lasers
基金
国家自然科学基金(52375308)。
关键词
双激光焊接
钛-钢异种金属焊接
微观组织
力学性能
dualbeam laser welding
titaniumsteel dissimilar metal welding
microstructure
mechanical properties
