Certified Welder Welding Processes & Techniques 2 — Questions and Answers
Question 1: Which welding process uses a consumable electrode wire fed automatically through a welding gun with shielding gas supplied externally?
- SMAW
- GMAW (Correct answer)
- GTAW
- SAW
Correct answer: GMAW
GMAW (Gas Metal Arc Welding / MIG) uses a continuously fed consumable wire electrode and externally supplied shielding gas.
Question 2: In submerged arc welding (SAW), the arc is shielded by:
- Compressed argon gas
- A flux-coated electrode
- A granular flux blanket (Correct answer)
- A ceramic backing
Correct answer: A granular flux blanket
SAW uses a granular flux that completely submerges the arc, preventing spatter and providing excellent shielding.
Question 3: What is the primary advantage of plasma arc welding (PAW) over GTAW?
- Lower equipment cost
- Higher energy density and faster travel speeds (Correct answer)
- No shielding gas required
- Suitable for all metals without pre-cleaning
Correct answer: Higher energy density and faster travel speeds
PAW constricts the arc through a nozzle orifice, producing a higher energy density plasma column that allows faster travel speeds and deeper penetration.
Question 4: Which FCAW mode uses only the flux inside the tubular electrode for shielding with no external gas supply?
- Dual-shield FCAW
- Gas-shielded FCAW
- Self-shielded FCAW (Correct answer)
- Open-arc FCAW
Correct answer: Self-shielded FCAW
Self-shielded FCAW (FCAW-S) relies entirely on the flux core of the electrode for shielding, requiring no external gas supply.
Question 5: During GTAW welding of aluminum, which current type is typically recommended?
- DCEN (electrode negative)
- DCEP (electrode positive)
- AC (alternating current) (Correct answer)
- High-frequency DC
Correct answer: AC (alternating current)
AC current is used for GTAW on aluminum because the positive half-cycle provides cathodic cleaning action to break up the oxide layer.
Question 6: In electroslag welding (ESW), the primary heat source is:
- An electric arc between electrode and base metal
- Resistance heating through molten conductive slag (Correct answer)
- Friction between a rotating tool and workpiece
- Combustion of acetylene and oxygen
Correct answer: Resistance heating through molten conductive slag
ESW is not an arc process; heat is generated by electrical resistance as current passes through the molten conductive slag pool.
Question 7: What does the term 'keyhole' refer to in plasma arc and laser welding?
- The shape of the weld bead cross-section
- A through-hole penetration technique for full-fusion welding (Correct answer)
- A backing bar slot used for root pass access
- The shape of the electrode tip
Correct answer: A through-hole penetration technique for full-fusion welding
Keyhole welding occurs when the concentrated heat source penetrates completely through the material, and the molten metal flows around and solidifies behind the moving heat source.
Certified Welder Welding Processes & Techniques 2
Which welding process uses a consumable electrode wire fed automatically through a welding gun with shielding gas supplied externally?