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TIG WELDING

Overview of Tungsten electrodes CODE

OXIDE ADDITIVES Wt.%

COLOUR CODE

REMARKS

WL10 WL15 WL20

0.90-1.20 La203

1.5 La203

1.80-2.20 La203

Black Gold Blue

Lanthanum AC and DC

WC20

1.80-2.20 Ce02

Grey

Cerium DC low current

Green

Pure Tungsten AC only

WP WZ8

0.70-0.90 Zr02

White

Zirconium AC only

WT10 WT20 WT30 WT40

0.90-1.20 Th02 1.80-2.20 Th02 2.80-3.20 Th02 3.80-4.20 Th02

Yellow Red Purple Orange

Thorium DC only

WS

Rare earths

Turquoise

AC and DC low current

Correct Grinding of Tungsten electrodes for DC welding For DC TIG welding use poined tip. For AC TIG welding use rounded tip. The angle of grinding depends on the welding current. If the electrode has too long a point compared to the welding current, the point will melt and contaminate the weld with tungsten deposit. Too short a point, give an unstable arc and insufficient heat consentration. Grinding must be done length wise, straight towards the point. Wrong grinding will result in an unstable arc and that bits of tungsten will brake off and fall into the weld deposit during welding.

Wrong grinding

x

xx x

4.02

15–20°

Correct Out of point centre

Too short a point

Correct grinding

Too long a point

Rounded tip

AC

DC 387