YAG激光焊接5A90铝锂合金金属蒸汽/等离子体特征

利用光谱测量、高速摄像等手段,对5A90铝锂合金YAG激光焊接过程中的金属蒸汽/等离子体的动态变化过程、光谱分布测量和计算表明:5A90激光焊接时金属蒸汽/等离子体几乎只从熔池正面喷出,主要强谱线为Li670.8,其次为镁和氩,温度大约为5600 K左右.在提出一种蒸汽反冲力估算方法的基础上,研究发现5A90焊接时最大蒸汽反冲力在5000～7000 Pa,而金属蒸汽/等离子体所有这些特征都与该材料中锂镁等元素的低沸点等特性相关.     

YAG激光等离子弧复合焊接热源光谱特征分析

利用所研制的YAG激光等离子弧复合热源,进行了不锈钢激光等离子弧复合焊过程的电弧、光致金属蒸气成像观察和光谱分析.研究结果表明,不锈钢的激光焊金属蒸气云与等离子弧具有完全不同的动态特征,其线光谱峰出现在不同的波长带,激光焊Ar谱线波长出现在 520 nm,等离子弧焊的Ar谱线波长均大于696 nm,当激光与等离子弧复合,线光谱是两者的组合,谱线强度增大,可观察到Fe、Cr和Ni等的特征光谱产生.复合焊线光谱特征与激光功率、焊接电流、热源间距和热源顺序密切相关,当热源间距很大时,复合焊的光谱特征实际上是两种热源特征光谱的简单组合,这主要取决于激光与电弧的相互作用.     

YAG-MIG复合焊接条件下复合等离子体动态特征

利用高速摄像,对单YAG、单MIG、YAG-MIG激光电弧复合焊接铝锂合金5A90时的等离子体动态过程进行了深入研究。结果表明:①YAG-MIG复合焊的等离子体在MIG弧存在阶段,与MIG弧具有相近之处,其周期性与MIG相似,但在MIG弧熄灭阶段与MIG焊和YAG焊都有明显的区别;②在强MIG等离子体复合强YAG等离子体时,复合焊的等离子体强度和形状发生明显变化,且不是二者的简单叠加结果。它呈现一种不规则的弧,充分说明尽管在单激光焊接时等离子体较弱,但在复合焊时,它对MIG弧的影响不容忽视;③在MIG微弧复合强YAG金属蒸气/等离子体时,发现其等离子体的强度高于单一激光焊,且形状也有较大差别,表明此时虽然MIG电弧仅为微弧,但它对YAG金属蒸气/等离子体有显著的影响。     

镁合金真空电子束深熔焊接及焊缝成形数值模拟

对10mmAZ61镁合金板材进行了真空电子束深熔焊接数值模拟研究.考虑到焊接过程中高温金属蒸气等离子体的热效应及真空电子束焊接"匙孔"深熔热效应特征,建立了高斯面热源与双椭球体热源复合的移动热源模型,采用数值模拟的方法研究了镁合金真空电子束焊接温度循环特征及不同焊接工艺对焊缝成形的影响.结果表明,建立的复合热源模型能够获得电子束深熔焊接的效果,并可模拟不同焊接工艺下的温度场分布与电子束热源作用下的焊缝成形,这也证明了该模型在AZ61镁合金电子束平板焊接的热效应模拟中有较好的适用性.     

YAG—MIG复合焊接条件下复合等离子体动态特征

利用高速摄像,对单YAG、单MIG、YAG—MIG激光电弧复合焊接铝锂合金5A90时的等离子体动态过程进行了深入研究。结果表明：①YAG—MIG复合焊的等离子体在MIG孤存在阶段,与MIG弧具有相近之处,其周期性与MIG相似,但在MIG弧熄灭阶段与MIG焊和YAG焊都有明显的区别;②在强MIG等离子体复合强YAG等离子体时,复合焊的等离子体强度和形状发生明显变化,且不是二者的简单叠加结果。它呈现一种不规则的弧,充分说明尽管在单激光焊接时等离子体较弱,但在复合焊时,它对MIG孤的影响不容忽视;③在MIG微弧复合强YAG金属蒸气／等离子体时,发现其等离子体的强度高于单一激光焊,且形状也有较大差别,表明此时虽然MIG电弧仅为微弧,但它对YAG金属蒸气／等离子体有显著的影响。     

工艺参数对铝合金CO2激光焊接光致等离子体温度的影响

利用Spectra Pro2500i瞬态光谱仪对6061铝合金CO2激光焊接光致等离子体的发光谱进行了测量,分析得到的200～600 nm范围内的MgI特征谱线,利用玻尔兹曼图法计算得到光致等离子体的平均温度.分别研究了激光功率、焊接速度、焦点位置、辅助气体等工艺参数对光致等离子体平均温度的影响,并对其原因进行了分析.在试验条件下,当激光功率超过材料深熔焊接阈值功率后,激光功率对光致等离子体温度的影响不大,约为6 000 K;焊接速度对光致等离子体温度的影响表现为"倒U形"曲线规律;对于一定内径的辅助气体喷嘴,等离子体温度随辅助气体流量呈现先增加后减小的趋势;在氦气中加入氩气会导致光致等离子体温度升高500～1 000 K左右.     

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...     

镁合金真空电子束焊接匙孔热效应数值模拟

分析了镁合金真空电子束焊接过程中的匙孔热效应特征,针对真空电子束焊接工艺建立了适用于镁合金焊接的复合热源模型.考虑到焊接过程中存在的高温金属蒸气等离子体及真空电子束焊接"匙孔"深熔效应特征,模型由高斯面热源和圆锥体热源复合而成,利用高斯面热源功率分配系数和圆锥体热源功率分配系数的不同取值,模拟电子束焊接的不同聚焦状态,并得到电子束聚焦状态与散焦状态下的焊接温度场变化,进而通过计算得到聚焦状态变化下的匙孔形状和焊缝成形.结果表明,模拟结果与其具有较好的一致性.     

5A05铝合金-917低磁钢爆炸焊复合板的MIG/MAG焊试验

通过对异种金属5A05铝-917低磁钢爆炸焊复合金属板MIG/MAG焊焊接工艺试验和力学性能试验,解决了我国某新型舰船生产中因焊接热循环及焊接热应力对复合面强度影响的关键问题,研发了适合5A05铝-917低磁钢爆炸焊复合板的焊接工艺,在该工艺条件下其结合面强度能够满足标准要求,可用于指导产品生产建造中的焊接施工.     

Analysis of energy utilisation efficiency in laser–GTA hybrid welding process

The effect of welding parameters on energy utilisation efficiency in laser–gas tungsten arc (GTA) hybrid welding process is investigated. Then, optimum butt joints are made by laser welding, GTA welding and laser–GTA hybrid welding, and the energy consumption in each process is calculated and compared. Both plasma and keyhole behaviours are studied. Results indicate that the parameter Dla greatly affects the energy utilisation efficiency in hybrid welding. The reason is that Dla determines keyhole behaviour and laser induced plasma, and these determine the coupling discharge of laser induced and GTA plasmas. Compared with laser and GTA welding, hybrid welding is more energy efficient.     

CO2 laser-micro plasma arc hybrid welding for galvanized steel sheets

A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-heat the weldment according to the arrangement of the laser beam and the arc. CO₂ laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.     

CO_2 laser-micro plasma arc hybrid welding for galvanized steel sheets

A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-heat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.     

42CrMo钢活塞激光-MAG复合焊接热裂纹试验

利用高速相机观测焊接时熔池流动和焊缝凝固过程,并求得固–液界面移动速率;利用红外热像仪采集焊缝温度随时间变化的相关信息,求得焊缝的温度梯度,对比研究42CrMo调质钢在激光焊接、激光引导的激光-MAG复合焊、电弧引导的激光–电弧复合焊三种焊接工艺时,焊缝接头处的热裂纹倾向.结果表明,激光引导的激光-MAG复合焊工艺比其它两种焊接工艺的固–液界面移动速率更小,焊缝的温度梯度也更小,具有最小的应变率和热裂纹敏感性.最后对激光引导的激光-MAG复合焊焊缝进行了显微组织观察和硬度分析.     

激光与电弧间距对激光复合焊熔滴过渡的影响

采用高速摄影设备研究了在两种焊接电流工艺参数下激光与电弧的间距变化对CO2激光-MIG电弧复合焊接熔滴过渡过程的影响.试验发现,在高速MIG焊接时熔滴过渡不稳定,在激光-MIG复合焊接时,由于激光光致等离子体对熔滴的热辐射作用和对电弧的吸引作用而改变了电弧的形态及相应的熔滴的受力状态,使得熔滴的过渡过程发生了改变,对于不同的焊接电流工艺参数,存在不同的最佳激光与电弧间距.结果表明,在最佳间距下,即两个等离子体的耦合作用良好时,熔滴过渡形式为单一的稳定射流过渡,电流电压恒定,焊缝成形良好.     

超高功率激光-电弧复合焊接特性分析

为了对超高功率激光-电弧复合焊接过程特性有深入的理解. 借助高速摄像,以焊接过程中羽辉和飞溅为主要研究对象,对比分析了激光功率从5 kW增加到30 kW时,激光热源与不同电弧热源复合,以及是否填丝对焊接特性的影响规律. 结果表明,激光功率增加,羽辉和飞溅面积的均值都呈增加趋势,两者的波动程度也呈上升趋势;冷丝的添加在降低焊缝熔深的同时使激光-MAG复合焊接过程中的稳定性变差;激光-TIG复合填丝焊接过程的稳定性明显优于另外两种焊接形式;高功率激光复合焊接时,高温羽辉对激光的散射和吸收作用会使熔深增加趋势放缓.     

辅助电流对Cu/Al大功率超声波焊接的影响

为获得更高质量的Cu/Al异质金属接头,开展了Cu/Al电流辅助大功率超声波焊接工艺试验,研究了辅助电流对Cu/Al超声波焊接的界面温度、材料塑性流动、界面中间相(IMC)分布及接头力学性能的影响。结果表明,复合焊件成型良好,其接头抗拉剪力为3030N,接头的断裂模式为韧性-脆性复合断裂。在同样的焊接时间0.2s内,随着电流的增大,Cu/Al界面温度增加,金属塑性流动以及界面扩散也随之增强,这说明辅助电流能明显促进界面冶金;相比长时间0.4 s的超声波焊接,辅助电流能在保证界面温度、材料塑性变形的前提下,能明显减薄界面IMC层的厚度,这是电流增强Cu/Al接头的主要物理机制。研究结果为优化Cu/Al复合焊接头强度提供了参考。     

铁素体不锈钢激光-MAG复合热源焊缝成形及接头冲击韧性分析

利用激光-MAG 复合热源分别进行了 T4003 和 TCS 铁素体不锈钢的焊接试验研究.通过与常规 MAG 焊的对比,测试分析了两种焊接方法的焊缝成形、接头的低温冲击韧性及接头的微观组织.结果表明,激光-MAG 复合热源焊接易于实现铁素体不锈钢的单面焊双面成形,与常规 MAG 焊相比,其焊接效率可以提高 1 倍以上.利用激光电弧复合热源可以提高铁素体不锈钢焊接接头的低温冲击韧性,较常规 MAG 焊,复合焊接头的低温冲击韧性可以提高 50%以上.激光-MAG 复合热源焊接接头热影响区粗晶区组织宽度明显小于常规 MAG 焊接头的粗晶区宽度.

Abstract：

Laser-MAG hybrid welding of T4003 and TCS ferrite stainless steels was studied. Through comparing with the conventional MAG welding of ferrite stainless steel, the results of the two welding methods including the appearance of weld, impact toughness under low temperature and the microstructure of the butt joints were tested and analysed. The analysing results show that it is easy to get one-side welding with back by laser-MAG hybrid welding. Comparing with the conventional MAG welding, the welding efficiency of ferrite stainless steel by laser-MAG hybrid welding can be improved more than one times, the low temperature impact toughness of the joints by laser-MAG hybrid welding can be improved over 50% than that of conventional MAG welding joints, and the width of coarsegrained zone of hybrid welding joints is thinner than that of MAG welding joints.