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In GTAW with DCEN, the shape of the electrode tip affects both the shape and power density distribution of the arc. As illustrated in Figure 2.10, as the electrode tip becomes blunter, the arc becomes more constricted, and the power density distribution increases. Glickstein [15] showed in Figure 2.11 that the arc becomes more constricted as the conical tip angle of the tungsten electrode increases.

Figure 2.10 Effect of electrode tip angle on shape and power density distribution of gas–tungsten arc.

Figure 2.11 Effect of electrode tip angle on shape of gas–tungsten arc.

Source: Glickstein [15]. Welding Journal, August 1976, © American Welding Society.

Savage et al. [16] observed that, under the same welding current, speed, and arc gap, the weld depth–width ratio increases with increasing vertex angle of the conical tip of the tungsten electrode. Key [17] reported a similar effect of the tip angle, at least with Ar shielding, as shown in Figure 2.12.

Figure 2.12 Effect of electrode tip geometry on shape of gas–tungsten arc welds in stainless steel (pure Ar, 150 A, 2.0 s, spot‐on‐plate).

Source: Drawn from photos of Key [17]. Welding Journal, December 1980, © American Welding Society.