高速激光热丝钎焊表面成形质量的控制

高速激光钎焊会引起熔池流动紊乱导致焊缝成形质量恶化,从而限制了其在汽车制造领域的应用。通过正交试验研究了高速下激光功率、送丝角度等工艺参数对焊缝成形质量的影响,发现焊缝成形质量随激光功率增加和送丝角度减小而提升。激光功率是通过影响熔池获得的热输入,从而影响熔池表面扰动的铺展来影响焊缝成形质量的。送丝角度是通过影响焊丝送入熔池的位置,从而影响焊丝对熔池的扰动强度和扰动的铺展速度来影响焊缝成形质量的。采用正交试验获得的最优工艺参数组合进行试验,获得了表面光滑平整无缺陷的高质量焊缝,为激光钎焊在高速下的应用发展奠定了基础。     

激光填丝焊焊丝熔入行为特征

采用高速摄像技术和工艺试验相结合的手段进行铝合金光纤激光填丝焊焊丝熔入行为及工艺特性研究.分析了焊丝熔入行为及其主要影响因素,研究了送丝方式与送丝角度对焊缝成形及焊接过程稳定性的影响.结果表明,依据光丝间距的不同,焊丝熔入行为可分为3种典型特征,铺展过渡、液桥过渡和大滴过渡,其中液桥过渡最为理想;前置送丝焊丝熔化效率高,工艺窗口较宽;送丝角度影响焊丝吸收激光能量程度以及液态焊丝对液态熔池的冲击力的大小,随着送丝角度的增加焊缝背部熔宽有明显增加,而焊缝熔深基本不变.     

钢铝异种金属对接接头激光填丝熔钎焊工艺研究

采用光纤激光和铝硅焊丝对2.5 mm厚6013铝合金和镀锌低碳钢的异种金属对接接头进行了激光填丝熔钎焊,试验研究了激光功率、偏移量、送丝速度等焊接工艺参数以及坡口角度对焊缝成形的影响,表征了典型焊缝界面处的微观组织,评估了钢/铝熔钎焊对接接头的抗拉强度。试验结果表明:在适当焊接参数下可以获得成形良好、无气孔缺陷和裂纹,且具有一定抗拉强度的钢/铝对接接头。在钢板采用30°坡口时,接头最大抗拉强度为88 MPa,45°坡口时强度可以达到135 MPa。     

基于摆动激光扫描的GMAW焊缝成形调控

将摆动激光与GMAW工艺复合,利用“8”字形摆动激光扫描液态熔池,对其温度场和流场进行调控,以改变熔池温度梯度,主动调控熔池流动以改善焊缝成形.在6061铝合金板材表面进行堆焊试验,重点探究了光丝间距、摆动幅度、激光功率对于焊缝成形的影响,采用高速摄像机拍摄激光扫描熔池过程.结果表明,摆动激光扫描可以有效抑制成形缺陷的发生,当摆动激光扫描熔池中部时可以获得最佳的焊缝成形效果.摆动激光扫描降低了熔池温度梯度分布,同时激光扫描产生的激光蒸发反力可以驱动熔池流动,促进了液态熔池的流动铺展,从而有效抑制了不规则焊缝成形缺陷,减少焊缝内部气孔和裂纹缺陷.调节摆动激光摆幅可以在一定范围内对焊缝宽度进行调控.     

9%Ni钢窄间隙激光填丝焊工艺参数对焊缝成形的影响

采用Ni基合金焊丝对16 mm厚的9%Ni钢板材进行了窄间隙激光填丝焊接。采用正交试验分析了激光功率、离焦量和光丝间距等工艺参数对焊缝成形的影响,并揭示了焊接过程中激光能量在熔池、匙孔、金属蒸汽及填充金属的分配路径。结果表明,增大激光功率和激光直接作用于侧壁母材均有利于增大侧壁熔合比;在较大离焦量及较小激光功率下的热导焊模式有助于焊缝表面成型;焊接过程中匙孔的不稳定是焊缝表面起伏的主要原因。     

非铁金属的焊接

20091169焊接工艺对6005A铝合金激光-MIG复合焊焊缝成形的影响/雷祥…//焊接.-2008(7):25~32采用CO2激光-MIG复合焊焊接2.5mm厚的6005A铝合金板,基于正交试验方法研究了焊接工艺参数对焊缝成形的影响。试验结果表明,对复合焊焊缝熔透状态影响显著性从大到小的工艺参数依次为:焊接速度、MIG电流、MIG电压和激光功率,其中前两者影响最为突出。在熔透状态不发生显著变化时,对复合焊焊缝表面成形影响显著性从大到小的工艺参数依次为:MIG电压、焊接速度、激光功率和MIG电流。根据正交试验结果优化了激光-电弧复合焊接6005A的工艺参数,建立了工艺参数选择原则,根据此原则选择合适的参数获得了最佳的焊缝成形。图4表6参13200911705A06铝合金激光填丝焊工艺研究/许飞…//焊接.-2008(8):26~28针对1.2mm厚5A06铝合金薄板YAG激光焊接工艺范围窄和对间隙要求严格等问题,较系统地研究了该铝合金激光填丝焊接工艺。试验中采用ER5356焊丝作为填充金属,对光丝间距、送丝速度、激光功率和焊接速度等影响焊缝成形的各种焊接工艺参数进行了优化分析。研究结果表明:优化工艺参数可以...     

非铁金属的焊接

20091169焊接工艺对6005A铝合金激光-MIG复合焊焊缝成形的影响/雷祥…//焊接.-2008(7):25~32采用CO2激光-MIG复合焊焊接2.5mm厚的6005A铝合金板,基于正交试验方法研究了焊接工艺参数对焊缝成形的影响。试验结果表明,对复合焊焊缝熔透状态影响显著性从大到小的工艺参数依次为:焊接速度、MIG电流、MIG电压和激光功率,其中前两者影响最为突出。在熔透状态不发生显著变化时,对复合焊焊缝表面成形影响显著性从大到小的工艺参数依次为:MIG电压、焊接速度、激光功率和MIG电流。根据正交试验结果优化了激光-电弧复合焊接6005A的工艺参数,建立了工艺参数选择原则,根据此原则选择合适的参数获得了最佳的焊缝成形。图4表6参13200911705A06铝合金激光填丝焊工艺研究/许飞…//焊接.-2008(8):26~28针对1.2mm厚5A06铝合金薄板YAG激光焊接工艺范围窄和对间隙要求严格等问题,较系统地研究了该铝合金激光填丝焊接工艺。试验中采用ER5356焊丝作为填充金属,对光丝间距、送丝速度、激光功率和焊接速度等影响焊缝成形的各种焊接工艺参数进行了优化分析。研究结果表明:优化工艺参数可以...     

激光填丝焊焊丝熔入行为研究

激光填丝焊接技术因其特有的优点提高了其焊接经济性,在增材制造和修复领域具有广阔的应用前景。然而焊丝熔入行为对焊接过程的稳定性和焊缝成形质量有很大影响。基于高速摄像采集技术和焊接工艺试验系统研究了焊丝熔入行为和焊缝成形质量之间的内部联系。结果表明,焊丝送进位置和送丝速度是影响焊丝加热熔化机制和液态金属过渡行为的关键因素;根据光丝间距的变化液态金属过渡行为可分为大滴过渡、液桥过渡和铺展过渡3种形式,其中液桥过渡时焊接过程最稳定且焊缝成形质量最好。     

中厚度TC4激光-TIG复合焊工艺研究

对5 mm厚TC4钛合金进行激光-TIG复合焊接工艺研究,分析不同焊接参数下焊缝组织与力学性能的差别。结果表明,由于存在TIG电弧辅助加热焊丝,接头的表面成形更为美观,气孔很少,在合理的光丝间距和送丝速度下,焊丝可以连续过渡到熔池,有利于焊缝成形;随着激光功率的增大,焊缝的熔宽和热影响区尺寸显著增加;焊缝的组织为α+β网篮状组织;焊缝的抗拉强度、抗弯强度均高于母材,随着热输入的减小,抗拉强度变大,抗弯强度变化不大,焊缝与热影响区的硬度均高于母材。     

铝/钢电弧辅助激光对接熔钎焊铺展特性

采用小功率TIG电弧辅助激光热源进行5A06铝合金和热镀锌ST04Z钢的预置粉末对接熔钎焊工艺试验,通过SEM,Photoshop来研究预留间隙、背面填涂钎剂、激光热输入、辅助电弧电流、热源中心间距、填加焊丝对熔钎焊接头铺展宽度的影响. 结果表明,预留小于0.5 mm的间隙与背面填涂钎剂均可增大铺展宽度;在未焊穿的前提下,随激光热输入和辅助电弧电流的增加,铺展宽度增大;随热源中心间距的增大,铺展宽度先增加后减小. 焊接熔池中填加Al-Si焊丝较未填加焊丝的铺展性更好,获得连续、美观的焊缝表面形貌.     

Stationary GMAW-P weld metal deposit spreading

Abstract

Non-isothermal spreading of non-travelling pulsed gas metal arc weld (GMAW-P) deposits was studied by experiments and numerical simulation. After an initial transient period, metal from the melting welding wire was deposited as a regular stream of droplets into a molten weld pool whose spreading was enhanced by direct arc heating of the solid substrate and weld pool convection. Accurate predictions of the final weld cross-section and time histories of base metal temperature and weld pool radius were produced by this simulation, which included mass, energy and momentum of transferring filler metal droplets. Dimensional analysis showed that speed of weld pool spreading was initially dominated by the momentum of liquid droplets while thermal convection by surface tension-driven flow became important at intermediate times. Eventually, the rate of spreading was matched to the thermal diffusion rate in the liquid. Capillary forces were never important in weld pool spreading. The weld metal deposit shape was well-approximated as a spherical cap with increasing volume and constant contact angle.     

焊丝熔化方式对激光焊接过程的影响

研究了两种焊丝熔化方法(电弧预熔丝激光焊、激光填丝焊)激光焊接过程对匙孔稳定性以及焊缝成形的影响,进一步研究了焊丝熔化方法对焊接接头质量的影响,并对比分析了两种焊丝熔化方式对焊接速度的适应性. 结果表明,电弧预熔丝激光焊过程中,熔池表面匙孔开口尺寸变化不大,匙孔较为稳定;激光填丝焊方法由于熔化的液态金属距离匙孔边缘很近,焊接过程中熔池表面匙孔开口尺寸变化较大,而且容易出现熔池表面匙孔的闭合. 与激光填丝焊相比,电弧预熔丝激光焊熔化的焊丝端部可以沿熔池边缘流入,与匙孔边缘的距离较远,匙孔稳定性较好,焊缝气孔数量较少. 当焊接速度为8 m/min时,电弧预熔丝激光焊的焊缝成形良好;而激光填丝焊焊缝背面成形不连续,并且出现了未焊透的缺陷.     

空间多位置摆动激光填丝焊接熔池动态行为及焊缝成形

以316L奥氏体不锈钢管道为研究对象,在摆动激光焊接研究基础上,对管道多位置激光填丝焊接熔滴过渡和焊缝成形展开研究,分析焊接熔池动态特征,优化各位置区间工艺参数,进而实现管道全位置激光焊接.结果表明,摆动激光束周期性的作用于填充焊丝,产生的反冲压力能够促进熔滴过渡,使得焊丝始终以"液桥"形式向熔池过渡;同时摆动激光增强了熔融金属侧向流趋势,提高熔池界面表面张力,削弱空间多位置下重力对熔池形貌的影响,保证各空间位置熔池均能稳定存在,焊缝成形连续均匀.     

聚变堆用奥氏体不锈钢不同激光输出模式熔丝特征

针对聚变堆用316LN奥氏体不锈钢材料,分别在连续激光和脉冲激光模式下进行了激光填丝焊接试验。主要研究了不同焊接工艺参数下的焊丝熔入特征及其对焊缝质量的影响,并对连续激光与脉冲激光焊接熔池流动及熔池形貌、接头的显微组织进行了研究。结果表明,连续激光填丝焊和脉冲激光填丝焊在合适的焊接工艺参数下均能获得焊丝液桥过渡,且熔池铺展均匀、焊缝成形良好。与脉冲激光填丝焊相比,连续激光填丝焊在坡口中的熔池长度约是脉冲激光填丝焊的3倍,温度梯度较大,更易产生侧壁未熔合和贯穿焊缝中心的凝固裂纹等缺陷。连续激光填丝焊的焊缝显微组织以柱状晶为主,由焊缝两边向焊缝中心生长,方向性强。脉冲激光填丝焊的焊缝两侧显微组织以柱状晶为主,各个区域都受到了相邻脉冲的重复作用,具有周期性,产生二次结晶,有助于熔池的搅动和晶粒细化,打乱了枝晶生长的方向性;焊缝中心区域为方向各异的柱状晶和等轴晶,枝晶间距减小,能够抑制裂纹的产生。 创新点： 首次提出通过脉冲激光调控结晶形态以抑制厚板焊接中裂纹的焊接工艺,可在不添加任何外部设备的基础上实现对裂纹的有效控制,打破了传统焊接工艺带来的局限性。     

Influence of molten metal flow on undercutting formation in GMAW

Molten metal flow on weld pool surface in gas metal arc welding process is investigated using a vision-based sensing system and an interpolation algorithm. Bead formation is investigated by analysing flow patterns and its driving forces of weld pool under different welding speed, welding current and shielding gas. Results show that if longitudinal to transverse velocity ratio exceeds 2.0 in the front of weld pool, outward molten metal mainly driven by arc force cannot reach the widest section of the weld pool. Meanwhile, the transverse spreading of molten metal is still hindered in the middle of weld pool as it turns to be inward flow dominated by Marangoni force. These phenomena impede molten metal supply to weld toes which causes undercutting defect. Scaling analysis shows that the predicted undercutting defect agrees well with that resulted from experiments.     

大功率光纤激光焊熔透状态模糊聚类识别方法

熔透是评价激光焊接质量的重要因素,但在焊接过程中难以直接检测熔透状态.以大功率光纤激光焊接304不锈钢紧密对接焊缝为试验对象,研究一种基于熔池红外热像的熔透状态识别方法.采用红外摄像机摄取焊接区域熔池动态图像,提取熔池特征量,应用模糊聚类算法分析熔池特征量与熔透状态之间的关系,使用模糊C-均值（FCM）和Gustafson-Kessel（GK）两种模糊聚类法建立熔透状态识别模型.激光焊接试验结果表明,熔池表征与熔透状态之间存在密切关联,通过GK模糊聚类算法建立的模型对熔透状态能达到78%以上的识别率,为大功率光纤激光焊接过程熔透状态的识别和控制提供试验依据.     

Effects of torch configuration and welding current on weld bead formation in high speed tandem pulsed gas metal arc welding of steel sheets

Abstract

Undercut and humping bead are the common defects that limit the maximum welding speed of tandem pulsed gas metal arc (GMA) welding. In order to increase the maximum welding speed, effects of the inclination angle, interwire distance and welding current ratio between the leading wire and trailing wire on bead formation in high speed welding are investigated. The undercut and humping bead is attributed to the irregular flow of molten metal towards the rear part of the weld pool. This irregular flow can be prevented by the trailing wire with a push angle from 5° to 13° , which provides an appropriate component of arc force in the welding direction. The irregular flow is also related to the distance between the leading wire and the trailing wire, and the flow becomes regular when the distance is in the range 9–12 mm. Moreover, the stabilisation of the bulge of the weld pool between the two wires, the presence of enough molten metal below the trailing arc, and the reduced velocity of molten metal flow towards the rear part of the weld pool, are essential to increase the maximum welding speed. These conditions can be obtained by adjusting the ratio of the leading arc current to the trailing arc current. A maximum welding speed as high as 4–4·5 m min^?1 is achieved by setting the current ratio to a value ranging from 0·31 to 0·5.     

Microstructural and mechanical characteristics of laser welding of Ti6Al4V and lead metal

Titanium alloy Ti6Al4V and lead metal were welded using a continuous wave Nd:YAG laser. The influences of laser power, scanning velocity, and laser beam offset on weld morphology were investigated. Microstructure, chemical composition and mechanical properties of the joints were evaluated. Experimental results showed that fusion weld formed at the upper part of the weld and brazing weld with solder of Pb formed at the lower part of the weld under appropriate process condition. Interfaces were formed between mixed fusion zone and liquid lead zone in molten pool during laser welding of Ti6Al4V and lead. Reasons for interface formation may be different driving force of various regions in molten pool, and the miscibility gap of Ti and Pb binary system. Ti-Pb intermetallic compound Ti₄Pb was detected at the fusion weld zone, which made the microhardness of the weld seam was higher than that of the base materials. The strength of the joint was at least equal to or larger than that of lead base material.