This paper focuses on the research on double-electrode gas metal arc welding(DE-GMAW) of AZ31 B magnesium alloy sheet with 2 mm thickness. During the welding process, stable hybrid arc of metal inert gas(MIG) and tung...This paper focuses on the research on double-electrode gas metal arc welding(DE-GMAW) of AZ31 B magnesium alloy sheet with 2 mm thickness. During the welding process, stable hybrid arc of metal inert gas(MIG) and tungsten inert gas(TIG) is employed as welding heat source. Optical and electron microscopes are used to observe the microstructures of the weld joint. X-ray diffraction(XRD) and energy dispersive spectroscopy(EDS) are employed to identify the components in fusion zone. Microhardness is also tested. When the MIG current is 80 A, the perfect weld joint is obtained, though figures of fish scales are observed in all joints in the research. The fusion zone is formed by dendrites, where β-Mg17(Al, Zn)12is dispersed. The hardness in fusion zone and heat affected zone(HAZ) is lower than that in base metal(BM). The average Vickers hardness of fusion zone and HAZ is about 58 and 56 respectively, while the Vickers hardness of BM is about 63.展开更多
Modification of conventional gas metal arc welding （GMAW） process is of great potential to achieve high productivity with low cost and strong usability. Double-Electrode GMAW （DE-GMAW） is such a modified arc weldi...Modification of conventional gas metal arc welding （GMAW） process is of great potential to achieve high productivity with low cost and strong usability. Double-Electrode GMAW （DE-GMAW） is such a modified arc welding process which is formed by adding a bypass torch （gas tungsten arc welding torch） to a conventional GMAW system. The mechanism of metal transfer in DE-GMAW was proposed and verified in this paper. Experiments show that the critical current is decreased so that spray transfer can be obtained at a lower current level in DE-GMAW. Analysis of this significant change in metal transfer phenomena is conducted, and explanation is given out. It is found that the bypass arc in DE-GMAW lifts the anode point on the droplets such that the electromagnetic force becomes larger and squeezes the droplets so that spray transfer can take place under welding current lower than that in conventional GMAW.展开更多
Double-electrode gas shielded arc welding （ DE - GMAW） was used to weld the magnesium alloy cylinder with the diameter of 200 mm and the thickness of 6 mm. In order to study the residual stress distribution of AZ31B...Double-electrode gas shielded arc welding （ DE - GMAW） was used to weld the magnesium alloy cylinder with the diameter of 200 mm and the thickness of 6 mm. In order to study the residual stress distribution of AZ31B magnesiunl alloy welding point, numerical sinmlation of welding temperature field, stress field and residual stress were carried out by MSC. mare software. The results show that the residual stress in the weld and the heat affected zone is large, and with the increase of the distance away from the weld center, the residual stress decreases. In most areas, the longitudinal residual stress is greater than the transverse residual stress （except for the inside and outside surfaces of the weld） , all of which provides theoretical support for the study of magnesiunl alloy welding residual stress.展开更多
基金the National Natural Science Foundation of China(No.61165008)the Scientific Research Foundation for Returned Scholars of Ministry of Education of China(No.13006199)
文摘This paper focuses on the research on double-electrode gas metal arc welding(DE-GMAW) of AZ31 B magnesium alloy sheet with 2 mm thickness. During the welding process, stable hybrid arc of metal inert gas(MIG) and tungsten inert gas(TIG) is employed as welding heat source. Optical and electron microscopes are used to observe the microstructures of the weld joint. X-ray diffraction(XRD) and energy dispersive spectroscopy(EDS) are employed to identify the components in fusion zone. Microhardness is also tested. When the MIG current is 80 A, the perfect weld joint is obtained, though figures of fish scales are observed in all joints in the research. The fusion zone is formed by dendrites, where β-Mg17(Al, Zn)12is dispersed. The hardness in fusion zone and heat affected zone(HAZ) is lower than that in base metal(BM). The average Vickers hardness of fusion zone and HAZ is about 58 and 56 respectively, while the Vickers hardness of BM is about 63.
基金the National Science Foundation of USA under grant DMI-0355324the National Natural Science Foundation of China under grantNo. 50675119
文摘Modification of conventional gas metal arc welding （GMAW） process is of great potential to achieve high productivity with low cost and strong usability. Double-Electrode GMAW （DE-GMAW） is such a modified arc welding process which is formed by adding a bypass torch （gas tungsten arc welding torch） to a conventional GMAW system. The mechanism of metal transfer in DE-GMAW was proposed and verified in this paper. Experiments show that the critical current is decreased so that spray transfer can be obtained at a lower current level in DE-GMAW. Analysis of this significant change in metal transfer phenomena is conducted, and explanation is given out. It is found that the bypass arc in DE-GMAW lifts the anode point on the droplets such that the electromagnetic force becomes larger and squeezes the droplets so that spray transfer can take place under welding current lower than that in conventional GMAW.
文摘Double-electrode gas shielded arc welding （ DE - GMAW） was used to weld the magnesium alloy cylinder with the diameter of 200 mm and the thickness of 6 mm. In order to study the residual stress distribution of AZ31B magnesiunl alloy welding point, numerical sinmlation of welding temperature field, stress field and residual stress were carried out by MSC. mare software. The results show that the residual stress in the weld and the heat affected zone is large, and with the increase of the distance away from the weld center, the residual stress decreases. In most areas, the longitudinal residual stress is greater than the transverse residual stress （except for the inside and outside surfaces of the weld） , all of which provides theoretical support for the study of magnesiunl alloy welding residual stress.
