Cold Metal Transfer technology has revolutionized the welding of dissimilar metals and thicker materials by producing improved weld bead aesthetics with controlled metal deposition and low heat-input. In this study, t...Cold Metal Transfer technology has revolutionized the welding of dissimilar metals and thicker materials by producing improved weld bead aesthetics with controlled metal deposition and low heat-input. In this study, the process, weld combinations, laser-CMT hybrid welding and applications of CMT welding are critically reviewed. Microstructure and other weld characteristics have been discussed at length for various base metal combinations. Particularly, the welding of aluminium and steel with better results has been possible with CMT Welding. The results reviewed in this article indicate that the CMT-Laser hybrid welding is more preferable to Laser or Laser hybrid welding. CMT welding has found applications in automobile industries, defence sectors and power plants as a method of additive manufacturing.展开更多
Two dissimilar materials, aluminum alloy and aluminum-coated steel, were joined by cold metal transfer process using AlSi5 filler wire. To this end, the steel was coated with Al-Si. The steel did not melt and aluminum...Two dissimilar materials, aluminum alloy and aluminum-coated steel, were joined by cold metal transfer process using AlSi5 filler wire. To this end, the steel was coated with Al-Si. The steel did not melt and aluminum was melt to form the joint during the process, it was actually cold metal transfer welding-brazing. The macrostructure, microstructure, alloy element distribution, and inter-metallic compounds were analyzed by optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy. It was found that the Al-Si coating dissolved into the weld metal. The pre-existing thin Fe-Al- Si ternary inter-metallic compounds in the interface between the Ak-Si coating layer and base metal steel also partially dissolved into the weld zone, tending to reduce the thickness of inter-metallic compounds. Approximate 3 μm thick undissolved intermetallic compound was found at the interface after welding which could guarantee sound bonding strength in dissimilar materials joining. The sample was fractured at the fusion zone near the aluminum side in the tensile test. The ultimate tensile strength was about 156 MPa, and the fracture mode is ductile failure in nature according to its morphology.展开更多
Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface...Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface defect under the parameters of welding current 121 A, welding voltage 15.4 V and welding speed 6 r/min. The microstructure of fiUer metal was analyzed by means of scanning electron microscopy. The filler metal and 6061 Al alloy were fused to form fusion welding interface, the fusion zone had a good bonding without any micro defect. The steel stud did not melt and brazing interface was formed between the filler metal and steel stud. Two different reaction layers existed in the brazing interface, the Fe2Al5 layer about 10 -12 p^m formed near the steel stud side, and the other layer was mainly composed of FeAl3. Nickel-rich zone was formed in the root toe area of the fillet weld, which was mainly composed of Al3Ni2. The tensile tests showed that the maximum shearing strength of the joints was 129 MPa. The joint was brittle fractured in the intermetallic compound layer where plenty of FeAl3 were distributed continuously.展开更多
针对增材制造过程中形成的缺陷会对工件造成不可逆的影响,分析了冷金属过渡(Cold metal transfer,CMT)增材制造过程的焊接电流信号和焊接电压信号,提出了一种基于时间序列算法的CMT增材制造缺陷在线监测方法。设置不同的焊接工况,收集...针对增材制造过程中形成的缺陷会对工件造成不可逆的影响,分析了冷金属过渡(Cold metal transfer,CMT)增材制造过程的焊接电流信号和焊接电压信号,提出了一种基于时间序列算法的CMT增材制造缺陷在线监测方法。设置不同的焊接工况,收集良好组和缺陷组的原始焊接电流和焊接电压信号,使用SAX(Symbolic aggregate approximation)算法对数据进行预处理。使用随机森林模型对数值型数据再分类,达到实时监测的效果;同时为突出SAX算法的优越性,设置对比试验组,将原始的焊接电流数据直接放入随机森林模型进行分类。结果表明,原始焊接电流组的测试集准确率为80%,SAX算法数据预处理组的测试集准确率为96%。展开更多
搭建了铝合金激光-冷金属过渡(Cold Metal Transfer,CMT)复合焊接试验平台和高速摄像采集平台,研究铝合金激光-CMT焊接过程中的熔滴特性.改变激光功率,获得不同焊接参数下CMT熔滴过渡的高速摄像图.通过对比分析可知,在激光功率较小时,...搭建了铝合金激光-冷金属过渡(Cold Metal Transfer,CMT)复合焊接试验平台和高速摄像采集平台,研究铝合金激光-CMT焊接过程中的熔滴特性.改变激光功率,获得不同焊接参数下CMT熔滴过渡的高速摄像图.通过对比分析可知,在激光功率较小时,激光主要起到引导电弧作用,对CMT电弧影响较小,焊接过程较为稳定,能够获得良好焊缝成形.当激光功率较大时,会影响CMT原有的短路过渡,造成熔滴飞溅等情况,导致焊缝成形较差.结果表明:保持焊丝和激光间距的有效距离和控制激光功率,是保证激光-CMT复合焊接过程稳定的关键.展开更多
综述了涉及工程应用的冷丝熔化极气体保护焊(Cold wire gas metal arc welding,CW-GMAW)熔滴过渡形态特征。结果表明,在大电流、强规范、富氩混合气体保护下,CW-GMAW工艺的熔滴过渡形态呈喷射过渡;当电流较小、电弧电压较低时,可能为滴...综述了涉及工程应用的冷丝熔化极气体保护焊(Cold wire gas metal arc welding,CW-GMAW)熔滴过渡形态特征。结果表明,在大电流、强规范、富氩混合气体保护下,CW-GMAW工艺的熔滴过渡形态呈喷射过渡;当电流较小、电弧电压较低时,可能为滴状过渡,甚至在弧压很低时,呈现短路过渡形态。该工艺电弧发生偏向冷丝的位移,弧长变短甚至发生短路,与冷丝送进速率比增高及冷丝在电弧中产生大量金属蒸气时弧柱电阻下降有关。在具有富氩混合保护气体的相同工艺参数下,CWGMAW转变电流比GMAW降低了4%~7%。焊接工艺参数对CW-GMAW和GMAW工艺熔滴过渡形态的影响规律大致相近,但前者因涉及冷丝送进速率比和电极焊丝送进速度,以及它们的匹配等,使焊接电流的影响更为复杂。展开更多
文中用AZ61镁焊丝以及冷金属过渡焊接方法对接形式连接镁合金AZ31和镀锌钢板,在焊接过程中保持焊接速度不变,通过调节送丝速度和对钢板开不同的坡口研究不同焊接工艺参数下焊缝的表面成形、接头的力学性能和微观组织结构.结果表明,通过...文中用AZ61镁焊丝以及冷金属过渡焊接方法对接形式连接镁合金AZ31和镀锌钢板,在焊接过程中保持焊接速度不变,通过调节送丝速度和对钢板开不同的坡口研究不同焊接工艺参数下焊缝的表面成形、接头的力学性能和微观组织结构.结果表明,通过调节合适的焊接参数以及坡口形式,镁-钢之间能形成焊缝成形美观、接头最大抗拉载荷达到4.02 k N的镁钢对接熔钎焊接头.并且熔钎焊接头包括镁侧的熔焊接头和钢侧的钎焊接头,钎焊接头由两部分组成,一部分是坡口面上的镁与裸钢板之间的钎焊接头,另一部分是镀锌钢板上表面的镁-镀锌钢之间的钎焊接头.镁-镀锌钢侧的钎焊连接主要由靠近镁侧的(α-Mg+Mg Zn)的共晶相,以及靠近钢侧的Fe-Al相反应层实现连接.无镀锌层的钢和镁连接主要依靠焊丝中的微量Al元素扩散到钢表面形成Fe/Al相来实现连接.展开更多
在长输油气管道的焊接施工中,管道的根部打底焊接质量非常重要。与过去传统的根焊相比,应用CMT(cold metal transfer)冷金属过渡技术,在管道焊接尤其是管道的外部根焊上,焊接质量和焊接效率得到了非常大的提升,可以获得良好的焊接效果...在长输油气管道的焊接施工中,管道的根部打底焊接质量非常重要。与过去传统的根焊相比,应用CMT(cold metal transfer)冷金属过渡技术,在管道焊接尤其是管道的外部根焊上,焊接质量和焊接效率得到了非常大的提升,可以获得良好的焊接效果。介绍了CMT系统的组成以及技术特点,应用结果表明该方案具有可行性。展开更多
文摘Cold Metal Transfer technology has revolutionized the welding of dissimilar metals and thicker materials by producing improved weld bead aesthetics with controlled metal deposition and low heat-input. In this study, the process, weld combinations, laser-CMT hybrid welding and applications of CMT welding are critically reviewed. Microstructure and other weld characteristics have been discussed at length for various base metal combinations. Particularly, the welding of aluminium and steel with better results has been possible with CMT Welding. The results reviewed in this article indicate that the CMT-Laser hybrid welding is more preferable to Laser or Laser hybrid welding. CMT welding has found applications in automobile industries, defence sectors and power plants as a method of additive manufacturing.
基金This research is supported by the National Natural Science Foundation of China （ No. 51005101 ）, Jiamusi University Scientific Research Project （12010 -118） and State Key Laboratory of Advanced Welding Production Technology Project （AWJ-M13 -04）.
文摘Two dissimilar materials, aluminum alloy and aluminum-coated steel, were joined by cold metal transfer process using AlSi5 filler wire. To this end, the steel was coated with Al-Si. The steel did not melt and aluminum was melt to form the joint during the process, it was actually cold metal transfer welding-brazing. The macrostructure, microstructure, alloy element distribution, and inter-metallic compounds were analyzed by optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy. It was found that the Al-Si coating dissolved into the weld metal. The pre-existing thin Fe-Al- Si ternary inter-metallic compounds in the interface between the Ak-Si coating layer and base metal steel also partially dissolved into the weld zone, tending to reduce the thickness of inter-metallic compounds. Approximate 3 μm thick undissolved intermetallic compound was found at the interface after welding which could guarantee sound bonding strength in dissimilar materials joining. The sample was fractured at the fusion zone near the aluminum side in the tensile test. The ultimate tensile strength was about 156 MPa, and the fracture mode is ductile failure in nature according to its morphology.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20131261)
文摘Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface defect under the parameters of welding current 121 A, welding voltage 15.4 V and welding speed 6 r/min. The microstructure of fiUer metal was analyzed by means of scanning electron microscopy. The filler metal and 6061 Al alloy were fused to form fusion welding interface, the fusion zone had a good bonding without any micro defect. The steel stud did not melt and brazing interface was formed between the filler metal and steel stud. Two different reaction layers existed in the brazing interface, the Fe2Al5 layer about 10 -12 p^m formed near the steel stud side, and the other layer was mainly composed of FeAl3. Nickel-rich zone was formed in the root toe area of the fillet weld, which was mainly composed of Al3Ni2. The tensile tests showed that the maximum shearing strength of the joints was 129 MPa. The joint was brittle fractured in the intermetallic compound layer where plenty of FeAl3 were distributed continuously.
文摘针对增材制造过程中形成的缺陷会对工件造成不可逆的影响,分析了冷金属过渡(Cold metal transfer,CMT)增材制造过程的焊接电流信号和焊接电压信号,提出了一种基于时间序列算法的CMT增材制造缺陷在线监测方法。设置不同的焊接工况,收集良好组和缺陷组的原始焊接电流和焊接电压信号,使用SAX(Symbolic aggregate approximation)算法对数据进行预处理。使用随机森林模型对数值型数据再分类,达到实时监测的效果;同时为突出SAX算法的优越性,设置对比试验组,将原始的焊接电流数据直接放入随机森林模型进行分类。结果表明,原始焊接电流组的测试集准确率为80%,SAX算法数据预处理组的测试集准确率为96%。
文摘搭建了铝合金激光-冷金属过渡(Cold Metal Transfer,CMT)复合焊接试验平台和高速摄像采集平台,研究铝合金激光-CMT焊接过程中的熔滴特性.改变激光功率,获得不同焊接参数下CMT熔滴过渡的高速摄像图.通过对比分析可知,在激光功率较小时,激光主要起到引导电弧作用,对CMT电弧影响较小,焊接过程较为稳定,能够获得良好焊缝成形.当激光功率较大时,会影响CMT原有的短路过渡,造成熔滴飞溅等情况,导致焊缝成形较差.结果表明:保持焊丝和激光间距的有效距离和控制激光功率,是保证激光-CMT复合焊接过程稳定的关键.
文摘综述了涉及工程应用的冷丝熔化极气体保护焊(Cold wire gas metal arc welding,CW-GMAW)熔滴过渡形态特征。结果表明,在大电流、强规范、富氩混合气体保护下,CW-GMAW工艺的熔滴过渡形态呈喷射过渡;当电流较小、电弧电压较低时,可能为滴状过渡,甚至在弧压很低时,呈现短路过渡形态。该工艺电弧发生偏向冷丝的位移,弧长变短甚至发生短路,与冷丝送进速率比增高及冷丝在电弧中产生大量金属蒸气时弧柱电阻下降有关。在具有富氩混合保护气体的相同工艺参数下,CWGMAW转变电流比GMAW降低了4%~7%。焊接工艺参数对CW-GMAW和GMAW工艺熔滴过渡形态的影响规律大致相近,但前者因涉及冷丝送进速率比和电极焊丝送进速度,以及它们的匹配等,使焊接电流的影响更为复杂。
文摘文中用AZ61镁焊丝以及冷金属过渡焊接方法对接形式连接镁合金AZ31和镀锌钢板,在焊接过程中保持焊接速度不变,通过调节送丝速度和对钢板开不同的坡口研究不同焊接工艺参数下焊缝的表面成形、接头的力学性能和微观组织结构.结果表明,通过调节合适的焊接参数以及坡口形式,镁-钢之间能形成焊缝成形美观、接头最大抗拉载荷达到4.02 k N的镁钢对接熔钎焊接头.并且熔钎焊接头包括镁侧的熔焊接头和钢侧的钎焊接头,钎焊接头由两部分组成,一部分是坡口面上的镁与裸钢板之间的钎焊接头,另一部分是镀锌钢板上表面的镁-镀锌钢之间的钎焊接头.镁-镀锌钢侧的钎焊连接主要由靠近镁侧的(α-Mg+Mg Zn)的共晶相,以及靠近钢侧的Fe-Al相反应层实现连接.无镀锌层的钢和镁连接主要依靠焊丝中的微量Al元素扩散到钢表面形成Fe/Al相来实现连接.
文摘在长输油气管道的焊接施工中,管道的根部打底焊接质量非常重要。与过去传统的根焊相比,应用CMT(cold metal transfer)冷金属过渡技术,在管道焊接尤其是管道的外部根焊上,焊接质量和焊接效率得到了非常大的提升,可以获得良好的焊接效果。介绍了CMT系统的组成以及技术特点,应用结果表明该方案具有可行性。
