Which symptom indicates the post-flow duration was too short?

• A. Tungsten oxidation and crater contamination
• B. Bead looks shiny and uniform
• C. Arc stability improves
• D. Gas consumption decreases

Answer: (A)

Post-flow duration is the time the shielding gas keeps flowing after you finish the arc to protect the tungsten and the weld crater as they cool. If that post-flow is too short, air can reach the hot tungsten and the crater end of the weld, causing tungsten oxidation and crater contamination. Oxidized tungsten can introduce contaminants into the weld and make the crater area look dull or discolored, which is a clear sign shielding protection ended too soon. A bead that looks shiny and uniform usually means the shielding was adequate, so the wrap-up flow wasn’t cut short. If arc stability seems to improve or if gas consumption drops, those aren’t direct indicators of too-short post-flow; they point to other factors in shielding or process settings.