Welding arc energy characteristic regulation

Abstract

When welding pipes, due to the concentration of magnetic field lines in a ferromagnetic pipe with high magnetic permeability, the welding current magnetic field increases, magnetic blow, under. by the action of electromagnetic force, the arc length increases up to a break, the current and voltage on the arc fluctuate significantly, the seam dimensions change from a point to a large width, the process stability is disturbed, the welds formation and the welded joints impact toughness is reduced. Based on the study of the arc energy characteristics, according to which the voltage on the arc increases with increasing arc length, it was found that the arc moves along the tape end at a speed of 3.3 m/s, the electrode shape affects the welding arc. energy and voltage characteristics. In this case, the sum of near-electrode voltage drops depends on the work function of electrons from the cathode surface of the flux components and does not depend on the electrode shape, which confirms the main role of field emission in the arc and the arc concentration below. pinch-effect. To increase the welded joints impact toughness, it is necessary to reduce energy, heat input, crystal lattice microdistortions, microstresses, dislocation density, welding stresses, reduce the weld width, heat-affected zone, the deposited metal amount and refine the microstructure. An effective way to reduce energy is to increase the welding speed, which reduces the heat input, and reduce the arc length, arc voltage, which leads to an increase in the arc rotation speed, pinch effect, arc concentration and energy, heat input efficiency, reduce welding stresses, increase the crystallization rate, the microstructure refinement, the interatomic distance reduction and interatomic bonds increase. A process for one-sided high-speed welding of pipes for gas and oil pipelines with a low-energy composite electrode, which, due to low arc voltage, arc concentration, stability, energy reduction, heat input, welding stresses, microstructure refinement, interatomic distance reduction and interatomic bonds increase, provides an increase in the welded joints impact toughness 2-2.5 times has been developed. Minimum energy – maximum welded joints impact toughness