The Effect Of Mn And Al-Mg Alloy On Welding Performance Of Slag-free Self-shielded Flux Cored Wire

As one new kind of welding consumables, self-shield flux-cored wire is widely used inhardfacing alloy repairing. It has several advantages, such as high deposition rate, excellent anti windcapability and simple welding procedure. There is a wide gap between the processing performance offlux-cored wire in China and abroad. In this paper a new type of slag-free self-shield flux-cored wirebased on Fe-C-Cr-B was developed. The effect of manganese and aluminum-magnesium alloycontents on the droplet transition style, welding spatter, pore sensitivity and arc shape of the slag-freeself-shield flux-cored wire were studied.The pore sensitivity of the wire was investigated by using surface pores quantities and speciestesting. The results showed that, pore sensitivity decreased with the increase of the contents ofmanganese and aluminum-magnesium alloy. When the contents of manganese andaluminum-magnesium alloy were6wt.%and6wt.%respectively, the pore sensitivity was thelowest.The wire`s arc shape was investigated by high-speed photography. The results showed that thearc length shortened, the arc shapes had a transition in cup arc--circle conoid arc--cup arc and themetallurgical reactions aggravated with the increase of manganese contents. With the increase ofaluminum-magnesium alloy contents, the anodic spot diameter decreased firstly, and then increased,meanwhile, the cathodic flame dimeter increased; welding root areas became bigger and the arc spraydrift actived more largely; the arc length and root diameter increased, also the arc was burning moreviolently; and the arc shapes had a transition in circle conoid arc--cup arc. When the contents ofmanganese contents and aluminum-magnesium alloy were6wt.%and6wt.%respectively, the arcwas the most stable.Spatter testing and the speed photography method were adopted to observe the droplet transitionand spatter. To collect the droplet in the welding process, the wet water method was implemented.With the increase of manganese contents, the droplets became smaller and the spatters decreased;however, the size of droplets and spatters and the quantities of large scale repelled transfer firstdecreased and then increased. With the increase of aluminum-magnesium alloy contents, the dropletsbecame smaller, the spatters decreased, the scale of repelled transfer became bigger; however, the sizeof droplets and spatters first decreased and then increased. When the contents of manganese andaluminum-magnesium alloy were6wt.%and6wt.%respectively, the size of droplets, spatters and the quantities of large scale repelled transfer were the smallest.Based on the optimum contents of manganese and aluminum-magnesium alloy in the wire, theprocessing performance of the self-shield flux-cored wire was better than that of domestic wires.Moreover, this study offers a good platform for practical application in the future.