AWS Certified Welding Inspector — FundamentalsWelding ProcessesEasy
A CWI is observing a Shielded Metal Arc Welding (SMAW) operation on a structural steel component. The welder is using an E7018 electrode. Which of the following is the primary reason for maintaining a short arc length with this electrode?
- ATo improve arc starting characteristics.
- BTo increase the deposition rate.
- CTo minimize hydrogen pickup and porosity.
- DTo ensure proper shielding gas coverage.
Show answer & explanationAnswer & explanation
Correct answer: C. To minimize hydrogen pickup and porosity.
Maintaining a short arc length with E7018 electrodes is crucial for minimizing hydrogen absorption from the atmosphere, which helps prevent hydrogen-induced cracking and porosity in the weld metal. This electrode type is specifically designed to be low-hydrogen.
Why the other options are wrong
- A. Arc starting is more related to open-circuit voltage and electrode coating, not primarily arc length during welding.
- B. While arc length can affect deposition, it's not the primary reason for a short arc with E7018.
- D. SMAW electrodes provide their own shielding from the flux, not an external shielding gas.
SMAW Arc Length Control
Arc length in SMAW is the distance between the electrode tip and the weld puddle. Proper control is essential for weld quality.
- Too long an arc can lead to porosity and spatter.
- Too short an arc can cause stubbing and poor fusion.
- Specific electrodes require specific arc length control.
Memory trick: Short arc, strong weld, no hydrogen woe.