Study On Narrow Gap Welding Progress Properties Of Slag-free Self-shielded Flux Cored Wire

The slag-free self-shielded flux cored wire is one of the most promising welding materials because of its high automation,obvious energy-saving and consumption-reducing effect.With the character of gas-free and slag-free,it can be used to make up slag inclusion in multi-layer welding and insufficient accessibility of external trachea on narrow gap welding.For realizing the application of slag-free self-shielded flux cored wire in narrow gap welding.The key technical issues of sidewall fusion and arc stability need to be solved.Therefore,high-manganese / high-alumina slag-free self-shielded flux cored wires were developed in this paper.And welding properties of slag-free self-shielded flux-cored wire in narrow gap structure has been studied.Arc physics behavior of slag-free self-shielded flux-cored wire in narrow gap has been studied.Short circuit transfer,arc and slag bridge coexistence transfer,repelled transfer,globular transfer all are existence when two kinds of wire were used in 12 mm narrow gap welding.The arc stability of wires in 8 mm narrow gap space is worse than that in 12 mm narrow gap space.Process properties of slag-free self-shielded flux-cored wire in narrow gap has been studied.The welding soot of high manganese welding wire in narrow gap welding is higher than that of high-alumina welding wire.The narrow gap welding space can optimize the spatter rate,slag rate and depositing efficiency of the two kinds of welding wires in varying degrees.In macro morphology of 12 mm narrow gap weld,high-manganese welding wire is more likely to appear pores than high high-alumina welding wire because of the complexity of reactive gases.On the view of sidewall fusion,the best parameters of high-manganese welding wire is 260 A,30V,and the best range of parameters of high-alumina welding wire are 260~280A,27~30V.There are no better performances of process performance and sidewall fusion in 8mm narrow gap space when slag-free self-shielded flux-cored wire be used.The applicability of slag-free self-shielded flux-cored wire in narrow gap welding was analyzed.The process properties of two welding wires on 12 mm narrow gap welding is good,and base metal can be extended to all kinds of steel grades.In view of the design of welding wire alloy system based on 30 CrSiA medium carbon quenched.Considering the narrow gap mechanical properties of 30 CrSiA steel,The microstructures of two kinds of wires deposited metals both are pearlite,the microhardness values are all above 500 HV.So high manganese/high alumina flux-cored wires with slag-free self-shielded have better applicability in narrow gap welding of the steelsArc physics and process porperties of slag-free self-shielded flux cored wire in narrow gap has been studied in this paper.The applicability of slag-free self-shielded flux cored wire in narrow gap welding of specific steel grades is analyzed.It provides theoretical and experimental basis for the application of slag-free self-shielded flux cored wire in narrow gap welding structure.