AWS Flux-Cored Arc Welding (FCAW) 4 — Questions and Answers
Question 1: In FCAW-G, what is the primary purpose of the external shielding gas?
- To cool the weld pool faster
- To protect the molten weld pool from atmospheric contamination (Correct answer)
- To increase wire feed speed
- To reduce spatter by pressurizing the arc
Correct answer: To protect the molten weld pool from atmospheric contamination
External shielding gas in FCAW-G shields the molten weld pool from oxygen, nitrogen, and moisture in the surrounding atmosphere.
Question 2: Which condition is most likely to cause porosity when using FCAW-S (self-shielded) outdoors?
- Electrode extension too short
- Wind speed exceeding 5 mph disrupting flux shielding (Correct answer)
- Travel speed too slow
- Workpiece angle too steep
Correct answer: Wind speed exceeding 5 mph disrupting flux shielding
High wind disperses the gaseous shield produced by the flux core, allowing atmospheric gases to contaminate the weld pool and cause porosity.
Question 3: What does a 'T-1' designation indicate in an AWS FCAW electrode classification such as E71T-1C?
- Single-pass welding only
- Rutile-type flux designed for flat and horizontal positions with CO2 shielding (Correct answer)
- Self-shielded electrode for all positions
- High-cellulose coating for vertical-down welding
Correct answer: Rutile-type flux designed for flat and horizontal positions with CO2 shielding
The T-1 usability designator indicates a rutile (titania) slag system suitable for all-position welding with CO2 or mixed-gas shielding.
Question 4: When welding with FCAW in the vertical-up position, which parameter adjustment best prevents the weld pool from sagging?
- Increase voltage to flatten the bead
- Reduce heat input by lowering amperage and travel speed slightly (Correct answer)
- Increase wire feed speed for more fill
- Switch to a larger diameter electrode
Correct answer: Reduce heat input by lowering amperage and travel speed slightly
Lowering heat input reduces the fluidity of the weld pool, making it easier to control and preventing sagging in the vertical-up position.
Question 5: What is the typical electrode extension (stickout) range for FCAW?
- 1/8 to 1/4 inch
- 3/4 to 1-1/2 inches (Correct answer)
- 2 to 3 inches
- 3 to 4 inches
Correct answer: 3/4 to 1-1/2 inches
FCAW typically uses 3/4 to 1-1/2 inch electrode extension, which is longer than GMAW to allow for resistance heating that improves deposition rate.
Question 6: Which type of current polarity is most commonly used for FCAW-G electrodes?
- AC (alternating current)
- DCEN (direct current electrode negative)
- DCEP (direct current electrode positive) (Correct answer)
- Pulsed AC
Correct answer: DCEP (direct current electrode positive)
Most FCAW-G electrodes operate on DCEP, which provides stable arc characteristics and good penetration.
Question 7: A welder notices the slag from an FCAW weld is difficult to remove and tightly adhered. What is the most likely cause?
- Travel speed too fast
- Voltage set too low causing a short, convex bead (Correct answer)
- Wire feed speed too high
- Gas flow rate too high
Correct answer: Voltage set too low causing a short, convex bead
Low voltage produces a convex bead profile that traps slag beneath the weld edges, making removal extremely difficult.
AWS Flux-Cored Arc Welding (FCAW) 4
In FCAW-G, what is the primary purpose of the external shielding gas?