Abstract
It has been considered that the anode of TIG arc is a disc of a certain diameter, and the arc is always stable and stand still, and that the weld dimension is determined by a set of welding conditions indifferent to the steel composition. This conviction was upset by the finding that minor element such as O and/or S influences penetration greatly. Okada observed that the metal composition influences anode pattern and penetration. Aim of this experiment is to clarify the precise shape and behavior of He arc anode, by means of electric potential measurement of base metal and arc atmosphere, developed by Okada, and video observation. Anode pattern changes according to arc length, current and S% of steel, and its movement coincided well with potential curve.
Discussions were given on the effect of various factors on the anode behavior and convections in the weld pool.
