Tungsten Inclusions
Tungsten inclusion is a discontinuity found only in TIG welding. Particles of tungsten from the electrode can be embedded in a weld when improper welding procedures are used. Typical causes are as follows:
- The Contact of electrode tip with molten weld pool.
- Contact of the filler metal with hot tip of electrode.
- Contamination of the electrode tip by spatter from the weld pool.
- Exceeds the current limit for a given electrode size or type.
- Extension of electrodes beyond their normal distances from the collet (as with long nozzles) resulting in overheating of the electrode.
- Inadequate tightening of holding collet or electrode chuck.
- Inadequate shielding gas flow rates or excessive wind drafts resulting in oxidation of the electrode tip.
- Defects such as splits or cracks in the electrode.
- Use of improper shielding gases such as argon - oxygen or argon - CO2 mixtures that are used for gas metal arc welding