TIG weld porosity: a practical checklist
Check gas supply, base metal, filler, parameters and environment in that order.
When porosity appears on the surface or inside the weld, work through the following sequence: 1) Gas: argon purity should be at least 99.99%. Check bottle residual pressure, hose leaks and flowmeter accuracy. 2) Base metal: confirm the surface is free of oil, rust and moisture. Rolling oil and marker pen residue are common hydrogen sources on 304 and 316L. 3) Filler: damp filler wire introduces hydrogen directly. Store it dry after opening and bake it if the manufacturer requires. 4) Parameters: excessive current deepens the pool and can break shielding; excessive gas flow creates turbulence that draws in air. 5) Environment: add a wind screen when air velocity exceeds 2 m/s. Change one variable at a time and record the result, otherwise the root cause cannot be isolated.