AWS Certified Welding Inspector — FundamentalsWelding ProcessesMedium
A CWI is reviewing a Weld Procedure Specification (WPS) for Gas Metal Arc Welding (GMAW) of a 1-inch thick carbon steel plate. The WPS specifies a short-circuit transfer mode for all passes. Which of the following is a significant limitation of using short-circuit transfer on material of this thickness?
- AExcessive penetration leading to burn-through.
- BLack of fusion due to insufficient heat and penetration.
- CIncreased risk of hydrogen-induced cracking.
- DHigh heat input causing distortion.
Show answer & explanationAnswer & explanation
Correct answer: B. Lack of fusion due to insufficient heat and penetration.
Short-circuit transfer is a low heat input process, making it suitable for thin materials or root passes on thicker material. However, on thick-section material (like 1-inch plate) for fill or cap passes, its insufficient heat and penetration capabilities can lead to lack of fusion, especially in groove welds, making it generally unsuitable for full-thickness welding on such heavy sections.
Why the other options are wrong
- A. Short-circuit transfer is a low heat input process and is unlikely to cause excessive penetration or burn-through on thick material.
- C. Hydrogen-induced cracking is more related to moisture and base metal susceptibility, not a primary limitation of short-circuit transfer itself.
- D. Short-circuit transfer has the lowest heat input among GMAW transfer modes, so it's less likely to cause significant distortion compared to spray or pulsed-spray.
GMAW Short-Circuit Limitations
Short-circuit transfer in GMAW is a low heat input process with limitations on its use for thicker materials due to insufficient penetration.
- Low heat input, good for thin material.
- Prone to lack of fusion on thick sections.
- Risk of cold lap.
Memory trick: Short circuit on thick plate means a cold, poor fusion state.