Which factor is a common cause of porosity in TIG welds?

• A. Low current setting
• B. Poor gas coverage, contamination, or drafts
• C. Using high-quality filler material
• D. Fast travel speed with clean metal

Answer: (B)

In TIG welding, porosity mainly comes from the shielding gas not fully protecting the molten metal or from contaminants that mix with the weld pool. If coverage is poor, the shielding gas can’t displace the air around the weld, and atmospheric gases get trapped as the metal solidifies, forming pores. Drafts or turbulence can blow the shielding gas away, creating the same effect. Contaminants such as oil, grease, moisture, or other residues on the base metal or filler material introduce hydrogen or oxygen into the weld, also leading to porosity. So keeping a clean workpiece, proper gas flow, and a stable, undisturbed shielding environment is key.

Low current setting changes heat input and fusion but isn’t the main cause of porosity. Using high-quality filler helps reduce inclusions and porosity, not cause it. Fast travel speed with clean metal can cause other defects like lack of fusion or improper bead shape, but not porosity driven by shielding gas issues.