What post-weld cleaning steps are appropriate for stainless steel welded with GMAW to preserve corrosion resistance?

• A. Remove spatter, wipe clean, and if required, perform passivation or cleaning steps per code; avoid contamination that could reduce corrosion resistance.
• B. Only grind until smooth; no cleaning.
• C. Painting over welds is sufficient.
• D. Stainless steel requires no cleaning.

Answer: (B)

Stainless steel welds rely on a protective chromium oxide passive film to resist corrosion, so post-weld care must both clean the surface and restore that film. The correct approach is to remove spatter, wipe the area clean, and then perform passivation or other code-approved cleaning steps to re-establish the passive layer. This sequence prevents contaminants and iron pick-up from creating sites of corrosion and discoloration around the weld.

Grinding alone isn’t sufficient because it can remove or damage the protective passive film and may embed particles into the surface, which can still promote corrosion. Painting over welds or skipping cleaning entirely do not reliably restore the corrosion-resistant surface, especially in weld zones where the microstructure and chemistry have been altered by welding.