Flux Cored Wire Arc Arc Gap Welding Droplet Transfer And Weld Formation Research

According to the swing arc narrow gap MAG welding,this paper constructed a high-speed video acquisition system with background light,and analyzed the droplet transfer characteristics,welding spatter forms and arc stability for solid wire and flux-cored wire.Besides,it researched on the influence on welding formation by different process parameters in flat welding position,which included swing frequency,swing angle and the duration time on both sidewalls.Meanwhile,when some process parameters in the condition of vertical-up welding position remain unchanged,such as swing process parameters,wire feed rate and linear heat input,it observed the influence on welding formation by wire feed rate and welding speed which changed simultaneously.In the flat and vertical-up welding positions,the transfer frequency variation of droplet is different from its transfer forms.When welding flux-cored wire,the transfer frequency of droplet when the wire stayed in the central position of the groove was larger than that of stable arc staying on the sidewalls when the swing frequency was relatively large.On the contrary,the transfer frequency of droplet when the wire stayed in the central position of the groove was smaller than that of stable arc staying on the sidewalls when the swing frequency was relatively small.It had the same rule as solid wire as flux-cored wire with relatively small swing frequency in the process of droplet transfer.In the flat welding position when welding solid wire and flux-cored wire,the arc was more stable when swing frequency was 1.5Hz and 2.5Hz.In addition,the forms of welding spatter in the process mainly were streaming transfer spatter and small drop transfer spatter,and there were a few splash blast as well.In vertical-up welding position,the arc was relatively stable when swing frequency was 0.6Hz and 0.8Hz.Besides,the forms of welding spatter mainly were streaming transfer spatter and drop transfer spatter,and there were a few splash blast and short-circuit blast at the same time.In the flat welding position,section area of welding slag of flux-cored wire decreased as swing frequency increased,and increased as the duration time on sidewalls and pre-welding gap increased.The variation trend of surface curvature of welding slag was opposite to the section area of welding slag.The sidewall penetration increased as swing frequency and duration time on sidewalls increased,yet the variation trend of bottom penetration was opposite to that of sidewall penetration.The decrease on pre-welding gap could increase both the bottom and sidewall penetration.In the vertical-up welding position,with the wire feed rate increasing,both the sidewall and bottom penetration increased,whereas the surface curvature of weld and welding slag decreased.Under the condition of certain welding linear heat input,it was beneficial to increase sidewall and bottom penetration with the help of the increase of wire feed rate and welding speed.