Troubleshoot weld porosity item by item across five dimensions: gas source, base metal, filler metal, process parameters, and environment.
When porosity appears concentrated on the weld surface or inside the weld, troubleshoot in the following order:
1) Gas source: Argon purity should be ≥99.99%; check the residual pressure of the gas cylinder, leaks in the lines, and the accuracy of the flow meter.
2) Base metal: Confirm the surface is free of oil, rust, and moisture; rolling oil and marker pen residue on 304/316L surfaces are common sources of hydrogen.
3) Filler metal: Moisture in the welding wire directly introduces hydrogen; store it dry after opening, and bake it as required by the manufacturer if necessary.
4) Parameters: Excessive current causes an overly deep molten pool and poor gas shielding; excessive gas flow instead creates turbulence that entrains air.
5) Environment: A wind screen must be added when wind speed exceeds 2 m/s.
During troubleshooting, change only one variable at a time and record it; otherwise the root cause cannot be identified.
