Study Of Optimization Of Processes And Joint Performance Of Aluminum/Galvanized Sheet By CMT Welding-brazing Process

Due to the large physical differences between aluminum and steel,the solderability of the aluminum/steel is poor,so the welding of aluminum/steel composite structures has become a hot topic.In this experiment,CMT technology was used to weld aluminum/galvanized sheet and optimize the welding process.The position of the welding wire was studied.The effect of the “CMT+P” pulse waveform parameters and the thickness of the galvanized layer on the lap welding of aluminum/galvanized sheet CMT.The orthogonal test method was used to optimize the CMT welding process of aluminum/galvanized sheet.Three factors and three levels were selected: wire feed speed,welding speed,and gas supply volume for protective gas.Based on the tensile results and using range analysis,the wire feeding speed was 6.0 m/min,the welding speed was 10 mm/s,and the air delivery volume was 10 L/min.Five different wire feeding positions were selected to study the influence of the lap welding of the aluminum/galvanized sheet on the formation and the quality of the welded joint.When the wire feeding position was on the galvanized sheet,the weld was not fully formed and the zinc layer evaporated seriously.When the wire feeding position is biased toward the aluminum plate,the weld seam is formed full,and when the wire feeding position is at the edge of the aluminum plate,a better welding joint is obtained.Select three parameters of pulse width,pulse current and number of pulses in “CMT+P” pulse waveform parameters.The wider the pulse width is,the wider the weld line is,and the weld seam near the side of the aluminum alloy plate has a depression with a pulse width of 0.5 ms.The welding capacity of the welded joint is the highest;the pulse current increases from 260 A to 300 A,the grain growth near the heat affected zone and fusion line of the aluminum alloy side of the weld is large,and the number of pulses changes to the weld appearance,weld Microstructure,the impact of joint tensile and shear loads are all small,and the fracture forms of welded joints are all ductile fractures at the center of the weld.The results of the influence of the galvanized layer thickness on the microstructure and properties of aluminum alloy/galvanized sheet lap joints show that the mechanical properties of the 10 ?m and 60 ?m welded joints are poor,the 30 ?m welded joints perform well,and the dendrite is present in the zinc-rich zone.Zinc thicker welding arc and the transition is more unstable,the arc edge is seriously upturned,the molten droplets splash pool.