Influence of Slot Defect Length on Magnetic Flux Leakage

(1) A mathematical model of weldpool surface deformation and keyhole formation in PAW+TIG DSAW process is developed on the basis of magnetohydrodynamic theory and calculus of variations with considering all kinds of dynamic factors acting on the weldpool. (2) Welding current of PAW+TIG DSAW process flows in from the TIG bottom side of workpiece, along the keyhole and metal neighborhood and away from the PAW topside of workpiece. The current of PAW+TIG DSAW process is mostly located in the round area with the radius of 2.0 mm. Under such technical conditions, the minimum keyhole radius is 0.5 mm and 89.5% of current flows through the keyhole when weldpool reaches quasi-steady state. (3) Welding current of normal PAW process flows in from one side of workpiece, along the top surface of this side and out away from the arc centerline neighborhood. Current density of normal PAW welding is mostly located on one side of workpiece, which is completely different from that of PAW+TIG DSAW process.