为了研究冷金属与脉冲复合焊(cold metal transfer and pulse,CMT+P)的焊接行为,使用PCI数据采集卡、高速相机、红外成像仪及声发射采集系统对焊接过程进行同步监测.发现脉冲射滴过渡发生前,焊机输出电流突增,同时焊丝尖端释放猛烈电弧...为了研究冷金属与脉冲复合焊(cold metal transfer and pulse,CMT+P)的焊接行为,使用PCI数据采集卡、高速相机、红外成像仪及声发射采集系统对焊接过程进行同步监测.发现脉冲射滴过渡发生前,焊机输出电流突增,同时焊丝尖端释放猛烈电弧光,随后熔滴滴入焊道,熔池温度增加,声发射(acoustic emission,AE)信号显示出1个波峰.发生CMT短路过渡时,焊机输出电流同时为焊丝熔化和焊丝伸出提供能量,待到焊丝尖端接触基板瞬间形成短路,熔池温度持续降低,AE信号微弱,伴随着熔滴因过热收缩而爆断,熔滴短路过渡完成.对AE信号进行离散傅里叶变换(discrete Fourier transform,DFT)后,可通过特征频率对CMT+P各个周期及阶段进行过程识别.结果表明,575 kHz和415 kHz可作为脉冲电弧周期和CMT短路周期的特征频率,推断180 kHz是脉冲电弧的特有频率,575 kHz的频率则是基础电弧提供,415 kHz处的频率则在CMT短路接触瞬间产生.展开更多
The electron beam welding-brazing being used to join 5A06 Al alloy to TC4 Ti alloy decreases the formation of brittle intermetallic compound.Experiments were carried out to study the influence of electron beam welding...The electron beam welding-brazing being used to join 5A06 Al alloy to TC4 Ti alloy decreases the formation of brittle intermetallic compound.Experiments were carried out to study the influence of electron beam welding parameters on the tensile strength of welds,based on an orthogonal test and analysis method.The welding parameters include beam current,welding speed,scanning figure,scanning frequency,figure size,beam offset and focus current.The optimum parameters for3 mm 5A06 Al alloy and 2 mm TC4 alloy were as follows：acceleration voltage was 60 kV,beam current was 11 mA,welding speed was 600 mm/min,focus current was 0 mA,scan figure was O,scanning frequency was 1 000 Hz and beam offset was 0.5 mm.The results show that the joints were with good appearance and quality welded by the optimum parameters.The successful joints could be gained and the maximum tensile strength of Al/Ti dissimilar alloy joints could be up to 222.61 MPa using electron beam welding-brazing.展开更多
Effects of Ni on microstructure and properties of aluminum-stainless steel TIG welding-brazing joint with Al-Si filler were studied. Different mass percentage of Ni powder was added in the flux separately. Results of ...Effects of Ni on microstructure and properties of aluminum-stainless steel TIG welding-brazing joint with Al-Si filler were studied. Different mass percentage of Ni powder was added in the flux separately. Results of tensile tests show that a significant improvement on mechanical properties of the butt joint is obtained using the modified flux. Moreover, obvious differences on microstructures of the interfaces were observed with Ni addition, that two intermetallic compound （IMC） layers at the interface change to one layer and the IMC thickness also decreases. Finally, effect mechanism of Ni was analyzed and discussed. Ni addition leads to an enrichment of element Si at the brazing interface, and furthermore suppresses the formation of intermetaUic compound. The reduction of IMC thickness is the main reason for the improvement of joint properties.展开更多
Dissimilar metals TIG welding-brazing of 5A06 aluminum alloy to SUS321 stainless steel has been carried out with Al-Sil2 eutectic filler metal and modified non-corrosive flux. The surface appearance and microstructure...Dissimilar metals TIG welding-brazing of 5A06 aluminum alloy to SUS321 stainless steel has been carried out with Al-Sil2 eutectic filler metal and modified non-corrosive flux. The surface appearance and microstructures of the joint were analyzed and the average tensile strength of the joint was estimated. The results show that a sound dissimilar metals joint is obtained by TIG welding-brazing. Slag and residual flux on steel surface can be removed by sanding easily. The joint has dual characteristics： in aluminum alloy side, it is a welded joint, while in stainless steel side, it is a brazed joint. The whole interface layer, unequal in thickness at different position, ranges from 5 μm to 25 μm. The average tensile strength of the butt joint reaches 120 MPa and the fracture occurs at the interface layer.展开更多
Dissimilar metals TIG welding-brazing of aluminum alloy and non-coated stainless steel was investigated. The resultant joint was characterized in order to identify the phases and the brittle intermetallic compounds （...Dissimilar metals TIG welding-brazing of aluminum alloy and non-coated stainless steel was investigated. The resultant joint was characterized in order to identify the phases and the brittle intermetallic compounds （IMCs） in the interracial layer by optical metalloscope （OM）, scanning electron microscopy （SEM） and energy dispersive spectrometer （ EDS） , and the cracked joint was analyzed in order to understand the cracking mechanism of the joint. The results show that the microfusion of the stainless steel can improve the wetting and spreading of liquid aluminum base filler metal on the steel suuface and the melted steel accelerates the formation of mass of brittle IMCs in the interracial layer, which causes the joint cracking badly. The whole interfacial layer is 5 -7 μm thick and comprises approximately 5μm-thickness reaction layer in aluminum side and about 2 μm-thickness diffusion layer in steel side. The stable Al-rich IMCs are formed in the interfacial layer and the phases transfer from （ Al ＋ FeAl3 ） in aluminum side to （ FeAl3 ＋ Fe2Al5 ） and （ α-Fe ＋ FeAl） in steel side.展开更多
文摘为了研究冷金属与脉冲复合焊(cold metal transfer and pulse,CMT+P)的焊接行为,使用PCI数据采集卡、高速相机、红外成像仪及声发射采集系统对焊接过程进行同步监测.发现脉冲射滴过渡发生前,焊机输出电流突增,同时焊丝尖端释放猛烈电弧光,随后熔滴滴入焊道,熔池温度增加,声发射(acoustic emission,AE)信号显示出1个波峰.发生CMT短路过渡时,焊机输出电流同时为焊丝熔化和焊丝伸出提供能量,待到焊丝尖端接触基板瞬间形成短路,熔池温度持续降低,AE信号微弱,伴随着熔滴因过热收缩而爆断,熔滴短路过渡完成.对AE信号进行离散傅里叶变换(discrete Fourier transform,DFT)后,可通过特征频率对CMT+P各个周期及阶段进行过程识别.结果表明,575 kHz和415 kHz可作为脉冲电弧周期和CMT短路周期的特征频率,推断180 kHz是脉冲电弧的特有频率,575 kHz的频率则是基础电弧提供,415 kHz处的频率则在CMT短路接触瞬间产生.
基金supported by the National Natural Science Foundation of China(Grant No.51105346)
文摘The electron beam welding-brazing being used to join 5A06 Al alloy to TC4 Ti alloy decreases the formation of brittle intermetallic compound.Experiments were carried out to study the influence of electron beam welding parameters on the tensile strength of welds,based on an orthogonal test and analysis method.The welding parameters include beam current,welding speed,scanning figure,scanning frequency,figure size,beam offset and focus current.The optimum parameters for3 mm 5A06 Al alloy and 2 mm TC4 alloy were as follows：acceleration voltage was 60 kV,beam current was 11 mA,welding speed was 600 mm/min,focus current was 0 mA,scan figure was O,scanning frequency was 1 000 Hz and beam offset was 0.5 mm.The results show that the joints were with good appearance and quality welded by the optimum parameters.The successful joints could be gained and the maximum tensile strength of Al/Ti dissimilar alloy joints could be up to 222.61 MPa using electron beam welding-brazing.
基金Acknowledgement The authors would like to appreciate the financial support from the National Natural Science Foundation of China （Grant No. 50874033）.
文摘Effects of Ni on microstructure and properties of aluminum-stainless steel TIG welding-brazing joint with Al-Si filler were studied. Different mass percentage of Ni powder was added in the flux separately. Results of tensile tests show that a significant improvement on mechanical properties of the butt joint is obtained using the modified flux. Moreover, obvious differences on microstructures of the interfaces were observed with Ni addition, that two intermetallic compound （IMC） layers at the interface change to one layer and the IMC thickness also decreases. Finally, effect mechanism of Ni was analyzed and discussed. Ni addition leads to an enrichment of element Si at the brazing interface, and furthermore suppresses the formation of intermetaUic compound. The reduction of IMC thickness is the main reason for the improvement of joint properties.
基金Supported by National Natural Science Foundation of China （50874033）.
文摘Dissimilar metals TIG welding-brazing of 5A06 aluminum alloy to SUS321 stainless steel has been carried out with Al-Sil2 eutectic filler metal and modified non-corrosive flux. The surface appearance and microstructures of the joint were analyzed and the average tensile strength of the joint was estimated. The results show that a sound dissimilar metals joint is obtained by TIG welding-brazing. Slag and residual flux on steel surface can be removed by sanding easily. The joint has dual characteristics： in aluminum alloy side, it is a welded joint, while in stainless steel side, it is a brazed joint. The whole interface layer, unequal in thickness at different position, ranges from 5 μm to 25 μm. The average tensile strength of the butt joint reaches 120 MPa and the fracture occurs at the interface layer.
基金Supported by National Natural Science Foundation of China （50874033）.
文摘Dissimilar metals TIG welding-brazing of aluminum alloy and non-coated stainless steel was investigated. The resultant joint was characterized in order to identify the phases and the brittle intermetallic compounds （IMCs） in the interracial layer by optical metalloscope （OM）, scanning electron microscopy （SEM） and energy dispersive spectrometer （ EDS） , and the cracked joint was analyzed in order to understand the cracking mechanism of the joint. The results show that the microfusion of the stainless steel can improve the wetting and spreading of liquid aluminum base filler metal on the steel suuface and the melted steel accelerates the formation of mass of brittle IMCs in the interracial layer, which causes the joint cracking badly. The whole interfacial layer is 5 -7 μm thick and comprises approximately 5μm-thickness reaction layer in aluminum side and about 2 μm-thickness diffusion layer in steel side. The stable Al-rich IMCs are formed in the interfacial layer and the phases transfer from （ Al ＋ FeAl3 ） in aluminum side to （ FeAl3 ＋ Fe2Al5 ） and （ α-Fe ＋ FeAl） in steel side.
