Welder Red Seal · Question
A welder is fabricating a stainless steel pipe joint using the Gas Tungsten Arc Welding (GTAW) process. After completing the root pass, visual inspection reveals a dark, sooty, and crumbly surface deposit on the weld bead. What is the most probable cause of this discoloration?
Dark, sooty, and crumbly deposits on a stainless steel GTAW weld often indicate severe oxidation due to inadequate shielding gas coverage. This leads to the for
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Question: A welder is fabricating a stainless steel pipe joint using the Gas Tungsten Arc Welding (GTAW) process. After completing the root pass, visual inspection reveals a dark, sooty, and crumbly surface deposit on the weld bead. What is the most probable cause of this discoloration?
Answer options: ✅ Inadequate shielding gas coverage
- Excessive welding current
- Too slow travel speed
- Contaminated filler wire
Correct answer: Inadequate shielding gas coverage
Explanation: Dark, sooty, and crumbly deposits on a stainless steel GTAW weld often indicate severe oxidation due to inadequate shielding gas coverage. This leads to the formation of chromium oxides, which appear as a dark, discoloured surface layer. While excessive current or slow travel speed can cause overheating and some discolouration, it typically manifests as a thicker oxide layer rather than a crumbly soot. Contaminated filler wire might introduce defects but usually not this specific type of surface discoloration.
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