WCL Welding Processes & Techniques 3 — Questions and Answers
Question 1: In flux-cored arc welding (FCAW), what is the difference between FCAW-S and FCAW-G?
- FCAW-S uses solid wire; FCAW-G uses flux-cored wire
- FCAW-S is self-shielded; FCAW-G requires external shielding gas (Correct answer)
- FCAW-S operates on DC-; FCAW-G operates on AC
- FCAW-S is for aluminum; FCAW-G is for carbon steel
Correct answer: FCAW-S is self-shielded; FCAW-G requires external shielding gas
FCAW-S is self-shielded (flux in the core provides shielding), while FCAW-G requires an external shielding gas for protection.
Question 2: What is the correct direction of travel for SMAW to prevent slag inclusions?
- Always push the electrode away from the puddle
- Keep the electrode angle so slag stays behind the arc, not ahead of it (Correct answer)
- Drag the electrode at 90° to the work surface
- Travel in the direction that creates the widest bead
Correct answer: Keep the electrode angle so slag stays behind the arc, not ahead of it
Proper electrode angle ensures slag flows behind the arc; if slag runs ahead, it becomes trapped and causes inclusions.
Question 3: Which AWS filler metal classification is used for mild steel GTAW (TIG) welding?
- ER70S-6 (Correct answer)
- E7018
- ENi-1
- ER308L
Correct answer: ER70S-6
ER70S-6 is the most common solid wire/filler rod for TIG welding mild (carbon) steel, offering good deoxidizer content.
Question 4: What is 'undercutting' in a weld, and what causes it?
- A groove melted into the base metal along the weld toe, caused by excessive heat or improper angle (Correct answer)
- A depression in the center of the bead caused by low amperage
- Weld metal that extends beyond the joint, caused by slow travel
- Trapped slag below the weld surface caused by poor technique
Correct answer: A groove melted into the base metal along the weld toe, caused by excessive heat or improper angle
Undercutting is a notch melted into the base metal at the weld toe, typically caused by excessive current, improper electrode angle, or fast travel speed.
Question 5: For plasma arc cutting (PAC), which gas is typically used as the plasma gas for cutting carbon steel?
- Pure argon
- Nitrogen or compressed air (Correct answer)
- 100% helium
- CO2
Correct answer: Nitrogen or compressed air
Nitrogen or compressed air is commonly used as the plasma gas for cutting carbon steel due to cost-effectiveness and clean cut quality.
Question 6: What is the purpose of preheating before welding high-carbon or alloy steels?
- To soften the steel so it is easier to weld
- To slow the cooling rate and reduce the risk of hydrogen cracking and hard heat-affected zones (Correct answer)
- To remove mill scale before welding
- To increase the strength of the finished weld
Correct answer: To slow the cooling rate and reduce the risk of hydrogen cracking and hard heat-affected zones
Preheating slows the cooling rate of the weld and HAZ, reducing hydrogen-induced cracking and preventing brittle martensite formation.
Question 7: Which welding position is designated '6G' and why is it significant for certification?
- Flat position on plate; easiest to certify
- Fixed 45° inclined pipe; qualifying in 6G covers all other positions (Correct answer)
- Vertical position on a rotating pipe
- Overhead position on a flat plate
Correct answer: Fixed 45° inclined pipe; qualifying in 6G covers all other positions
The 6G position is a fixed pipe inclined at 45°, and a welder who qualifies in 6G is considered qualified in all positions and joint types for pipe.
WCL Welding Processes & Techniques 3
In flux-cored arc welding (FCAW), what is the difference between FCAW-S and FCAW-G?