Laser-pulsed MIG hybrid welding technology of A6N01S aluminum alloy

Welding research of A6N01S-T5 aluminum alloy profile for high-speed train was done by using laser-MIG hybrid welding and MIG welding individually. And the weld appearance,welding distortion,mechanical properties of the joints and microstructures were analyzed. The test results demonstrated that high-efficient welding for the profile can be achieved by using laser-MIG hybrid welding,the speed of which can be over 3. 0 m/min. The processing had a good gap bridging ability,even if the gap of the butt joint was up to 2. 0 mm,a good weld appearance can also be got. While the hybrid welding speed was greater than 2. 5 m/min,the welding distortion of the laser-tandem MIG hybrid joints was just about 33% of that of the MIG joints,but the welding efficiency was over 3 times of MIG welding. And tensile strength of the hybrid joints was 85% of that of A6N01S-T5 base metal,9% higher than that of the MIG joints. Fatigue properties was tested individually with pulsed tensile fatigue method in the condition of 1 × 10~7 lifetime. The test results demonstrated that the fatigue strength of the joints was a little lower than that of base material,which could be up to 115 MPa. But the fatigue strength of hybrid welding joints was 107. 5 MPa,which was 23% higher than 87 MPa of MIG welding joints.

Research on laser-arc hybrid welding technology for long-distance pipeline construction

In recent years, the research on pipeline laser-arc hybrid welding technology has been the important and difficult in the field of welding all over the world. China Petroleum Pipeline Research Institute Co. Ltd. has firstly developed pipeline laser-arc hybrid welding system in China, and executed the welding tests based on X70/X80 steel. Preliminary experiment results showed that hybrid welding could meet the requirements of related standards such as API1104,ASME,etc., the mechanical properties of girth seam are qualified in the case that there were no internal defects. With the development of high-power fiber laser and the continuous improvement of welding equipment, laser-arc hybrid welding technology for pipeline field welding will be available soon.

CHARACTERISTICS OF DROPLET TRANSFER IN CO_2 LASER-MIG HYBRID WELDING WITH SHORTCIRCUITING MODE

LF6 aluminum alloy plates with 4.5 mm thickness are welded in this experiment. Welding is carried out by using the CO2 laser-MIG paraxial hybrid welding in fiat position. The experimental results indicate that the inherent droplet transfer cycle time of conventional MIG arc is changed due to the interaction between CO2 laser beam and MIG arc in the short-circuiting mode of laser-MIG hybrid welding. Because of the preheating action of CO2 laser to electrode and base material, the droplet transfer frequency of MIG arc is increased in the hybrid welding process. When laser power is increased to a certain degree, the droplet transfer frequency is decreased due to the effect of laser-induced keyhole. Furthermore, through analyzing the MIG welding current and arc voltage waveforms and the characteristics of droplet transfer in the hybrid welding process, the effect of laser energy and the action point between laser beam and arc on the frequency of droplet transfer and weld appearance is investigated in details.

The numerical simulation of laser-MIG hybrid welding for Invar alloy

Composites are widely applied to the manufacturing of aircraft in aviation. Forming of large-scale composite component in aircraft requires the corresponding mold with precise size. The laser-MIG hybrid welding has a significant advantage in the manufacturing of Invar mold for aircraft composites. This paper mainly introduces the application of the laser-MIG hybrid welding,and the distribution of thermal field and flow field on the Invar alloy laser-MIG hybrid three-layer welding is analyzed and discussed specifically.

Influence of laser on arcs in alternate arcing during laser-twin-arc hybrid welding process

In this study, multi-information including spectrum, high-speed photograph and electrical signal was adopted to explore the coupling mechanism of alternate burning in laser-twin-arc welding process. Laser provides a conductive, stable plasma channel for arcs. Plasma radiation strengthened especially in the center of the arc after hybrid. High temperature plasma erupting from keyhole provides an upward reacting force which can prevent droplet from transfer. The charged particles consisted in high temperature plasma reduce the voltage that maintains arc ignition or burning. The results show that laser can influence the arc shape, prevent droplet transfer, reduce resistivity and stabilize arcs.

Low-power YAG laser/arc hybrid welding of AZ-based Mg alloy

The results of recent researches on the weldability of laser/arc hybrid welding of AZ-based Mg alloy was presented.Experiments were conducted with a low-power(500 W) Nd:YAG laser and a TIG arc.The synergic effects and mechanical properties of the Mg joints by laser/arc hybrid welding were investigated,and the interaction mechanism of laser to arc was also discussed.The results show that Mg alloys can be easily welded in similar and dissimilar joints by laser/arc hybrid welding technique.With the arc power increasing,a higher weld depth is obtained,and the weld depths for laser and arc acting in combination(laser/arc) are two times higher than that of the total of laser and arc acting separately(laser+arc) in optimal conditions.The tensile strength and fatigue strength of the AZ31B joints welded by laser/arc hybrid process are equivalent to that of the based metal.Besides,the laser-induced plume/plasma images captured by high speed camera were used to study the interaction between laser beam and arc.

Effect of laser power on metal transfer in laser-double arcs P-MAG hybrid welding with single power source

The effect of laser power on metal transfer is studied under conditions of alternating combustion of double arcs in order to develop the welding process of the laser-double arcs pulsed metal active gas （P-MAG） hybrid welding with single power. Different laser power corresponds to different interactive mechanisms of laser and arc and to different methods of metal transfer in the hybrid welding. When the laser power ascends from 500 W to 1 500 W, the methods of metal transfer change from the complex transfer of one droplet per pulse, one droplet two pulses and one droplet much more pulses during the mixture of globular and projected transfer of the lead wire, and from one droplet two pulses and one droplet three pulses during globular transfer of the follow wire to the methods of the metal transfer of both lead wire and follow wire are stable one droplet two pulses and one droplet three pulses when the metal transfer is mainly globular. The arc sharps and pressure of droplet are altered with the laser power changing. The compression of the arcs is strengthened by the laser and the offset of the center of droplet mass is much more obvious with the increasing of the laser power.

Experimental study on gas metal arc welding and laser hybrid welding of WYS700 steel

Gas metal arc welding, laser welding, and laser-metal active gas welding(MAG) hybrid welding methods were applied to WYS700 steel.Different welding procedures were performed and different welding technologies were compared.Macro metallographs of the welded joints were obtained, and the mechanical properties(such as tensile strength, bending property, and hardness) of the joints formed using the different welding technologies were determined.The results revealed that the joint of the WYS700 steel could be formed well through gas metal arc welding, laser welding, and laser-MAG hybrid welding.Furthermore, the softening of the welding heat affected zone can be effectively reduced to obtain good strength and plasticity by using a suitable welding procedure.Laser-MAG hybrid welding allows the realization of high efficiency and deep penetration for the welding of thick plates with specifications above 3 mm.

Mathematical analysis of the role of recoil pressure in weld pool dynamics during laser-MIG hybrid welding

A mathematical model was established to simulate the weld pool development and dynamic process in stationary iaser-MlG hybrid welding. Surface tension and buoyancy were considered to calculate liquid metal flow patter, moreover, typical phenomena of MIG welding, such as filler droplets impinging weld pool, electromagnetic force in the weld pool, and typical phenomena of laser beam welding, such as recoil pressure, Inverse Bremsstrahlung absorption, Fresnel absorption were all considered in the model. The laser beam and arc couple effect were introduced into this model by the plasma width during hybrid welding. The role of recoil pressure in the weld formation was discussed. Transient weld pool shape and complicated liquid metal velocity distribution from two kinds weld pool to an unified weld pool were calculated. The simulated weld bead geometry with consideration recoil pressure was in good agreement with experimental measurement.

Numerical simulation of temperature field in laser-arc hybrid welding of wear-resistant steel

Using ABAQUS software and cylindrical ellipsoid and body heat sources with a peak-heat-flux- attenuation function, a finite element model of the temperature field in the laser-arc hybrid welding of 4.5-mm BW300TP wear-resistant steel is proposed. The proposed model considers convection, radiation, molten pool flow, and heat conduction effect on temperature. A comparison of the simulation and actual welding test results confirms the reliability of the model. This welding heat-process model can provide the cooling rate at any position in the heat affected zone （HAZ） and can be used as a reference for the analysis of material properties and for process optimization.

Novel hybrid method: pulse CO_2 laser-TIG hybrid welding by coordinated control

In continuous wave CO2 laser-TlG hybrid welding process, the laser energy is not fully utilized because of the absorption and defocusing by plasma in the arc space. Therefore, the optimal welding result can only be achieved in a limited energy range. In order to improve the welding performance further, a novel hybrid welding method--pulse CO2 laser-TIG arc hybrid welding by coordinated control is proposed and investigated. The experimental results indicate that, compared with continuous wave CO2 laser-TIG hybrid welding, the absorption and defocusing of laser energy by plasma are decreased further, and at the same time, the availability ratio of laser and arc energy can be increased when a coordinated frequency is controlled. As a result, the weld appearance is also improved as well as the weld depth is deepened. Furthermore, the effect of frequency and phase of pulse laser and TIG arc on the arc images and welding characteristics is also studied. However, the novel hybrid method has great potentials in the application of industrials from views of techniques and economy.

基于SYSWELD的铝合金角接接头激光-MIG复合焊变形模拟

采用SYSWELD有限元软件对多种夹持条件下的5mm厚的L形铝合金角接接头的激光-MIG复合热源焊接变形进行数值模拟,并与实际焊接结果进行比较。研究表明:该软件能较好地模拟L形角接接头的激光-MIG复合焊,模拟结果与实际变形偏差为10%,夹持近焊缝处和焊缝冷却到室温时卸下夹具,更利于控制L形铝合金结构的激光-MIG复合焊接变形。

能量配比对6 mm 7A52铝合金板材VPPA-MIG复合焊接残余应力分布的影响

VPPA-MIG复合焊接的热源由VPPA和MIG两种电弧热源混合而成,该焊接方法集合了MIG焊接效率高、参数区间宽以及VPPA焊接能量集中、穿透深度大等优点,能够实现不同厚度铝合金板材的高效率和高质量焊接。在铝合金板材VPPA-MIG复合焊接过程中,VPPA与MIG两种电弧不同能量配比会影响焊后接头的残余应力分布。以6 mm厚7A52铝合金板材为试验材料,设置VPPA电弧能量配比不同的焊接参数进行VPPA-MIG复合焊接试验,焊后采用钻孔法测试并分析了接头残余应力分布及峰值大小。结果表明,复合焊接接头的熔合区和热影响区出现拉应力,母材区出现压应力。在复合焊接热源总能量不变的情况下,残余应力峰值随VPPA电弧能量配比的增加而增大,且当VPPA电弧能量配比从35%增大至40%时,可以获得成形效果良好的复合焊缝,横向残余应力峰值不超过73 MPa,纵向残余应力峰值不超过232 MPa,不会出现过大的残余应力峰值。与单MIG焊接相比,VPPA-MIG复合焊的残余应力峰值比单MIG焊大,而高应力区要比单MIG焊窄。

Application and development in railway vehicles trend of new welding technologies manufacturing industry

This paper introduces the application of new automatic welding technologies in railway vehicles manufacturing industry, and presents the state of art of advanced friction stir welding technology, semi-penetration laser welding technology and laser-arc hybrid welding technology in manufacturing aluminum alloy body shell, stainless steel body shell and bogie. This paper also analyzes the application and development trend of three welding technologies in the future.

12 mm厚TC4钛合金激光-MIG复合焊接头组织与性能研究

目的探究TC4激光-MIG复合焊接头显微组织与基本力学性能之间的联系,分析接头不同区域的断裂行为。方法利用激光-MIG复合焊制备TC4钛合金对接接头,采用光学显微镜和扫描电镜观察接头焊缝区、热影响区及母材的显微组织,在室温下进行了显微硬度测试、拉伸性能测试与断裂韧性测试,并对试样断口进行了观察分析。结果接头的焊缝区组织为粗大的β相柱状晶,晶内纵横分布着αʹ针状马氏体和针状α相,靠近焊缝一侧的热影响区则由针状αʹ相、α集束与少量细小的块状α相构成。随着远离焊缝中心,母材侧热影响区组织转变为块状的α相、少量α集束及初生β相,并最终趋于与母材组织相似。热影响区的显微硬度值达到最大,这是因为该区域存在比焊缝区更为细小的针状αʹ相。接头的平均抗拉强度和断后伸长率分别为1020.22 MPa和7.38%。接头在拉伸时主要在焊缝区发生断裂。焊缝区展现出比母材区和热影响区更优异的断裂韧性,平均值为87.14 MPa·m1/2,焊缝区内纵横交错的网篮组织与集束是其断裂韧性较高的主要原因。结论在TC4钛合金的激光-MIG复合焊过程中,针状α相和αʹ马氏体的存在会提高焊缝的显微硬度和断裂韧性,但相较于母材塑性没有提升,通过调控焊缝区显微组织结构,可以获得所需性能的接头。

FEM Simulation of Distortion and Residual Stress Generated by High Energy Beam Welding with Considering Phase Transformation

A series of experiments was carried out so as to elucidate the effect of the phase transformation in the cooling process on welding distortion and residual stress generated by laser beam welding (LBW) and laser-arc hybrid welding (HYBW) on the high strength steel (HT780). Then, the experiments were simulated by 3D thermal elasticplastic analysis with FEM (Finite Element Method) which was performed with using the idealized mechanical properties considering the transformation superplasticity. From the results, the effects of the phase transformation on welding distortion and residual stress generated by LBW and HYBW were elucidated. Furthermore, the generality of the idealization of the mechanical properties was verified.

Ti6321合金激光-MIG复合焊接接头组织和力学性能分析

对6 mm厚的Ti6321钛合金板开展激光-MIG复合焊接试验,对焊接接头的微观组织和力学性能进行了测试分析。结果表明,焊缝区金相组织主要为粗大的β柱状晶和细小的针状α’相形成的网篮组织;热影响区金相组织分布不均匀,近焊缝区组织主要由针状马氏体α’相和等轴α相组成,而近母材区组织主要由等轴α相、针状马氏体α’相和少量残余β相组成。拉伸断裂发生在远离焊缝的母材处,抗拉强度均值为935 MPa。焊缝和热影响区的硬度明显高于母材,最高硬度值出现在熔合线附近。

激光-MIG焊接工艺参数对低成本钛合金焊缝成形的影响

【目的】旨在研究不同焊接工艺参数下打底焊缝与盖面焊缝的成形规律,探索最佳打底层与盖面层焊接工艺参数。【方法】以10 mm厚钛合金(TC4LCA)板为母材,使用激光-电弧复合焊接工艺方法,进行打底焊和盖面焊,并对焊接接头进行宏观形貌分析及力学性能测试。【结果】结果表明,在坡口形式为Y形,坡口角度60°,钝边厚度为4 mm,光丝间距为4 mm,激光功率3.0 kW,焊接速度1 m/min,MIG电弧电流为150 A的条件下,能够获得成形良好的打底层焊缝;在激光功率为1.0 kW,焊接速度为0.6 m/min,MIG电弧电流为200 A的条件下,两次填充能够获得成形良好的盖面层焊缝,接头未发现裂纹、气孔、夹渣等缺陷。【结论】采用激光-MIG焊接方法得到的接头强度较高,达到母材强度的97.8%。

12 mm厚TC4钛合金激光-MIG复合焊接头疲劳裂纹扩展行为研究

为探究12 mm厚TC4钛合金激光-MIG复合焊接头在不同区域的疲劳裂纹扩展行为,并分析微观组织与裂纹扩展之间的相互作用。利用体式显微镜、相显微镜、扫描电子显微镜和电子背散射衍射技术分别对接头不同部位的裂纹扩展速率,裂纹扩展路径的变化,接头不同区域的显微组织与裂纹扩展的交互作用和裂纹尖端周边组织的变形特征进行了深入探究。结果表明,在裂纹稳定扩展阶段,母材区域的裂纹扩展速率最大,分别是热影响区和焊缝区域裂纹扩展速率的1.16倍和1.81倍。当ΔK=20 MPa·m^(1/2),母材裂纹扩展速率为3.39×10^(-4)mm/cycle。裂纹尖端的IPF图表明,在焊缝区中存在的50°~70°的大角度晶界占比为36.36%,高于母材的11.91%和热影响区的11.65%,大角度晶界的存在使裂纹沿晶界偏转或消耗更多能量穿过晶界,增大裂纹扩展阻力,表现出较好的裂纹扩展抗性。母材和热影响区表现出沿晶脆性断裂和韧性断裂的混合断裂模式,而焊缝区主要呈韧性断裂模式。此外,EBSD分析结果表明,焊缝区裂纹尖端附近具有更高的几何位错密度,位错在马氏体边界聚集,导致裂纹沿晶界发生偏转,进一步阻碍了裂纹的扩展。施密特因子分析也表明,焊缝区组织间的取向差差异较大,导致其裂纹扩展门槛值较高。综上,焊缝区中存在的大量大角度晶界和高位错密度是焊缝区具有较高裂纹扩展抗性的主要原因。

激光-MIG复合角焊缝成形工艺研究

目前,复合焊接技术研究多关注于薄板拼接焊,角焊缝焊接仍采用单热源,焊缝成形效果差。针对8 mm厚的Q235低碳钢板角焊缝,研究了激光-MIG复合焊接时,各工艺参数对角焊缝成形尺寸及熔池状态的影响。结果表明:MIG弧焊熔池飞溅较大,焊缝熔深、熔宽均较小,加入激光热源后,激光对电弧有一定的稳定作用,熔深、熔宽均增大,余高减小。弧焊熔池尺寸随电流增大而增大,当激光熔池与弧焊熔池耦合较好时,有利于稳定熔池、减少飞溅;随热源间距增大,熔滴不再滴入激光作用区,耦合作用下降;随焊接速度提升,热源在单位长度焊缝作用时间变短,熔深、熔宽下降。当激光功率为1.5 kW,焊接电流为220 A,热源间距为2 mm,焊接速度为600 mm/min时,弧焊熔池与激光熔池耦合好,熔池最为稳定,焊缝成形最佳。