Study On Process Performance Of Graphene Modified Slag-Free Self-Shielded Flux Cored Wire

Slag-free self-shielded flux cored wire has the advantages of high efficiency,energy saving and easy to use.Graphene has the advantages of high conductivity,thermal conductivity and super large specific surface area.Moreover,relevant studies have pointed out that graphene can induce grain nucleation and refine grain.Therefore,the use of graphene is expected to solve the problems of poor self-protection effect and poor performance of slag-free self-shielded flux cored wire,so as to improve the performance of the weld.In this paper,0%,0.15%and 0.3%graphene were added to the self-made slag-free self-shielded flux cored wire to explore the influence of graphene on the performance of slag-free self-shielded flux cored wire.The results show that the optimum parameters of flux cored wire are I=270A,U=27.5V,V=200mm/min.under the optimum welding parameters,the weld formation,spatter rate,deposition efficiency,dilution rate and slag coverage of the wire are improved with the increase of graphene content,and the welding process with 0.3%graphene content is the best.The welding wires with 0%,0.15%and 0.3%graphene have experienced short circuit transition,arc bridge transition,repulsive transition and particle transition,but graphene has an effect on the width and brightness of welding arc.The forms of welding spatter are bubble spatter,necking spatter and arc force spatter.All kinds of spatters decrease with the increase of graphene content;The welding fume also decreases with the increase of graphene content.The welding parameters have a great influence on droplet diameter,and it is easy to produce agglomerate under low current and voltage;When the droplet diameter is greater than or equal to 1.5mm,the droplet mass ratio,number ratio and average mass of single droplet are higher than other parameters under the optimal welding parameters;The increase of graphene is helpful to promote the large particle transition.The large particle transition of 203#welding wire with 0.3%graphene content is more than that of the other two kinds of welding wires.The results show that the microstructure of deposited metal of welding wire with 0%,0.15%and 0.3%graphene respectively is mainly Fe₂B+-Fe;graphene plays a great role in refining grain,the more graphene content,the finer grain structure;moreover,with the increase of graphene content,the inclusion defects in Surfacing Structure of welding wire gradually decrease.