Effect of Electrode Geometry on Maximum Arc Pressure in Gas Tungsten Arc Welding

Abstract

Effects of an electrode geometry on the maximum arc pressure at a base metal were investigated in GTA welding.
Results obtained are as follows;
(1) The pressure increases with a decrease in a vertex angle of an electrode. But at the vertex angle of 45° the pressure has a peak value and then the pressure decreases with the decrease in the angle less than 45°.
(2) When a shape of an electrode tip is treated a frustum of a cone, the pressure decreases and a vertex angle is not effective on the pressure. This fact suggests that the pressure is dependent on temperature distribution near an electrode tip.
(3) Arc is more concentrative at the tip by such an arc characteristic that arc generates along the shortest path between an electrode and a base metal.
On the other hand, temperature at an electrode tip becomes high and arc disperses to an upper part of the electrode from the tip. As these results, the pressure has a peak value about the angle of 45°.
(4) When a diameter of an electrode increases, the pressure increases usually and such tendency is remarkable at the angle of 45°.
This fact is understood that a rise of temperature near the tip is prevented and arc concentrates at the tip according to increasing the diameter.