57 Tungsten Inclusions

Tungsten inclusions are particles from the non consumable tungsten electrode that enter the weld. The occasional contact between the electrode and the work or the molten metal may transfer particles of the tungsten into the weld deposit. Improper grinding of the tungsten electrode, or using an electrode too small in relation to the amperage setting, may cause tungsten spitting that can also result in tungsten inclusions in the weld.

A limited number of tungsten inclusions may be acceptable according to the applicable fabrication standard or code, but it will depend on the thickness of the part being welded. Tungsten inclusions are detected by radiographic testing (RT). Tungsten inclusions appear as bright indications on the developed film. This is because tungsten is denser than the lead which is used to identify the image quality indicators (IQI) for RT film identification.

Tungsten Inclusion Prevention

Tungsten inclusions can be minimized by using a high-frequency for arc starting, using a copper striker plate, or by striking the arc on the filler metal being used. Tungsten inclusions can also be reduced by using the proper type and size of tungsten electrode, grinding electrode tapers longitudinally and using the correct amperage to prevent tungsten spitting, blunting the tip of a tapered electrode to prevent it from falling into the weld pool, and by being careful not to dip the tip of the electrode into the weld pool.