The Paton Welding Journal, 2017, #3, 15-24 pages
Force interaction of arc current with self-magnetic field
V.F. Demchenko1, I.V. Krivtsun1, I.V. Krikent2 and I.V. Shuba1
E.O. Paton Electric Welding Institute, NASU
11 Kazimir Malevich Str., 03680, Kiev, Ukraine. E-mail: email@example.com
Dneprosky State Technical University
2 Dneprostrojevskaya Str., 51918, Kamenskoe, Ukraine
Detailed theoretical analysis of force interaction of welding current with self-magnetic field under the conditions of nonconsumable electrode arc welding was performed. Electromagnetic force (Lorentz force) is presented as a sum of vortex and potential forces, from which only the vortex component is capable of exciting the movement of plasma or molten metal. Centripetal vortex force generates magnetic pressure in arc plasma and weld pool metal. The gradient of this pressure induces magnetic force, oriented predominantly in the axial direction. The magnitude of this force is the greater the higher the current density in near-anode region of welding arc (on weld pool surface). Depending on the nature of electric current spreading in the arc column, three possible scenarios of arc plasma movement are considered: by the schematic of right and inverse cone, as well as in the form of two vortices, excited by current channel compression in near-cathode and near-anode regions of the arc. Presented theoretical postulates are illustrated by numerical calculations of distribution of magnetic pressure and magnetic forces in arc column plasma and in weld pool metal. It is established that electric current contraction on the anode intensifies hydrodynamic flows of molten metal, and, therefore, also convective energy transfer from central zone of weld pool surface to its bottom part, promoting an increase of penetrability of the arc with refractory cathode. 14 Ref., 1 Table, 12 Figures.
arc welding, nonconsumable electrode, molten metal, hydrodynamic flows, arc current, magnetic field, arc penetrability
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