Prevention Against the Magnetic Arc Blow in DC Arc Welding of Pipes

Abstract

This investigation was carried out to clarify the mechanism of the magnetic arc blow occurred in UOE pipe longitudinal inside seam welding by large current MIG arc welding process, and to establish the preventions against this phenomenon.
The magnetic flux density around the arc was measured with aid of simulated model. The results obtained are summarized as follows.
(1) The magnetic flux density around the arc in inside welding of pipes showed asymmetrical distribution.
(2) Welding arc is blown toward the lower density side i.e. molten pool.
(3) The asymmetrical disribution of magnetic flux density is caused by the earth current and welding current through the boom inserted to the pipe.
(4) The prevention against the arc blow is established on the basis of the results obtained.