In high speed MAG welding process, some weld formation defects may be encountered. To get good weld quality, the critical welding speed beyond which humping or undercutting weld bead can occur must be known for differ...In high speed MAG welding process, some weld formation defects may be encountered. To get good weld quality, the critical welding speed beyond which humping or undercutting weld bead can occur must be known for different conditions. In this research, high speed MAG welding tests were carried out to check out the effects of different factors on the critical welding speed. Through observing the weld bead profiles and the macrographs of the transverse sections of MAG welds, the occurrence tendency of humping weld was analyzed, and the values of critical welding speed were determined under different levels of welding current or voltage, and the effect of shielding gas compositions on the critical welding speed was also investigated.展开更多
Modern manufacturing industry demands low cost and high efficient welding processes to remain competitiveness in the time of globalization. In this study, conventional gas metal arc welding （GMAW） was modified, a do...Modern manufacturing industry demands low cost and high efficient welding processes to remain competitiveness in the time of globalization. In this study, conventional gas metal arc welding （GMAW） was modified, a double-electrode GMAW （DE-GMAW） system is developed and DE-GMAW process is implemented through optimization of the design and process parameters and suitable selection of igniting sequence of double arcs. High speed welding tests were carried out to examine the effects of different factors on occurrence of weld formation defects. Through observing the weld bead appearance in DE-GMA W, the values of critical welding speed were determined under different levels of welding current and welding speed.展开更多
Weld humping and undercut are the most common appearance defects in high speed welding. A high speed tandem TIG welding process was developed to suppress the formation of these appearance defects and to improve the pr...Weld humping and undercut are the most common appearance defects in high speed welding. A high speed tandem TIG welding process was developed to suppress the formation of these appearance defects and to improve the productivity of TIG welding. In this paper, the mechanical properties and microstructure of joints obtained front tandem and single 77G welding were tested and compared. The results show that the sound weld appearance can be obtained by tandem TIG welding at the welding speed of 3 m/min for 1.5 mm thick 409L stainless steel plate. The mechanical properties of the tandem T1G welded joint are in the similar level with single TIG welded joint. The analysis of the tandem TIG welding process indicates that the assistant arc with a push angle can prevent the liquid metal flowing backward to the trailing region of weld pool and the premature solidification of thin liquid layer in the gouging region.展开更多
Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding （GMAW-S） process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been...Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding （GMAW-S） process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been investigated by experimental method. The welding power source used for the research is an inverter with a special current waveform control. It is shown that the spatter decreases at first then increases with each increase of the low current period, current increase rate and the maximum current limit. The test results are provided for welding of 1 mm and 3 mm mild steel at speed of 1.2 m/min. The stable GMA W-S process under high speed welding condition has been achieved by optimizing the parameters.展开更多
Based on the theory of stability of the liquid metal under the action of surface tension,a physical mod- el is established for the mechanisms of the bead formation deferct' humping', which is generated durin...Based on the theory of stability of the liquid metal under the action of surface tension,a physical mod- el is established for the mechanisms of the bead formation deferct' humping', which is generated during high - speed welding.A boundary function is introduced to correct the model,theoretical results got by the model correspond well with the experimental phenomena. A two - dimensional conducting model is adoopted in the simulation of the temperature field during high - speed welding.Finally, the factors acting upon the stability of liquid metal are analyzed.展开更多
基金support for this research from the National Natural Science Foundation of China(Grant No.50675119)the Specialized Research Fund for the Doctoral Program of Higher Education in China(Grant No.20050422027).
文摘In high speed MAG welding process, some weld formation defects may be encountered. To get good weld quality, the critical welding speed beyond which humping or undercutting weld bead can occur must be known for different conditions. In this research, high speed MAG welding tests were carried out to check out the effects of different factors on the critical welding speed. Through observing the weld bead profiles and the macrographs of the transverse sections of MAG welds, the occurrence tendency of humping weld was analyzed, and the values of critical welding speed were determined under different levels of welding current or voltage, and the effect of shielding gas compositions on the critical welding speed was also investigated.
基金The authors wish to thank the financial support for this research from the National Natural Science Foundation of China （Grant No. 50675119）.
文摘Modern manufacturing industry demands low cost and high efficient welding processes to remain competitiveness in the time of globalization. In this study, conventional gas metal arc welding （GMAW） was modified, a double-electrode GMAW （DE-GMAW） system is developed and DE-GMAW process is implemented through optimization of the design and process parameters and suitable selection of igniting sequence of double arcs. High speed welding tests were carried out to examine the effects of different factors on occurrence of weld formation defects. Through observing the weld bead appearance in DE-GMA W, the values of critical welding speed were determined under different levels of welding current and welding speed.
基金This work was supported by Shandong Provincial Natural Science Foundation of China （Grant No. ZR2014EEM020） and the Independent Innovation Foundation of Shandong University, IIFSDU（ No. 2012TS034）.
文摘Weld humping and undercut are the most common appearance defects in high speed welding. A high speed tandem TIG welding process was developed to suppress the formation of these appearance defects and to improve the productivity of TIG welding. In this paper, the mechanical properties and microstructure of joints obtained front tandem and single 77G welding were tested and compared. The results show that the sound weld appearance can be obtained by tandem TIG welding at the welding speed of 3 m/min for 1.5 mm thick 409L stainless steel plate. The mechanical properties of the tandem T1G welded joint are in the similar level with single TIG welded joint. The analysis of the tandem TIG welding process indicates that the assistant arc with a push angle can prevent the liquid metal flowing backward to the trailing region of weld pool and the premature solidification of thin liquid layer in the gouging region.
文摘Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding （GMAW-S） process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been investigated by experimental method. The welding power source used for the research is an inverter with a special current waveform control. It is shown that the spatter decreases at first then increases with each increase of the low current period, current increase rate and the maximum current limit. The test results are provided for welding of 1 mm and 3 mm mild steel at speed of 1.2 m/min. The stable GMA W-S process under high speed welding condition has been achieved by optimizing the parameters.
文摘Based on the theory of stability of the liquid metal under the action of surface tension,a physical mod- el is established for the mechanisms of the bead formation deferct' humping', which is generated during high - speed welding.A boundary function is introduced to correct the model,theoretical results got by the model correspond well with the experimental phenomena. A two - dimensional conducting model is adoopted in the simulation of the temperature field during high - speed welding.Finally, the factors acting upon the stability of liquid metal are analyzed.
