AWS AWS Welding Processes & Equipment 5 — Questions and Answers
Question 1: What is the main advantage of electroslag welding (ESW) compared to conventional arc welding processes for thick plate joints?
- ESW produces lower heat input, minimizing distortion on thick sections
- ESW can complete a thick vertical joint in a single pass, significantly increasing productivity (Correct answer)
- ESW operates without any flux or slag, giving a cleaner weld
- ESW requires no power source since the reaction is exothermic
Correct answer: ESW can complete a thick vertical joint in a single pass, significantly increasing productivity
Electroslag welding is capable of joining very thick plates (75mm+) in a single vertical pass, dramatically reducing welding time compared to multi-pass arc processes.
Question 2: In SMAW, what does the designation 'E7018' indicate about the electrode?
- The electrode has a 70,000 psi tensile strength, is an all-position electrode, and has a low-hydrogen iron powder coating (Correct answer)
- The electrode has a 70,000 psi tensile strength, is for flat and horizontal positions only, and has a rutile coating
- The electrode has a 7,000 psi tensile strength and is used for overhead welding only
- The electrode operates on AC only and has a cellulosic coating
Correct answer: The electrode has a 70,000 psi tensile strength, is an all-position electrode, and has a low-hydrogen iron powder coating
E7018: E=electrode, 70=70 ksi min tensile strength, 1=all positions, 8=low-hydrogen iron powder flux coating suitable for AC or DC+.
Question 3: Which parameter is most critical to control in order to prevent porosity when using GMAW on galvanized steel?
- Increasing travel speed to minimize zinc vapor exposure time (Correct answer)
- Reducing wire feed speed below the manufacturer's minimum recommendation
- Using DCEN (straight polarity) instead of DCEP
- Switching to a cellulosic electrode coating
Correct answer: Increasing travel speed to minimize zinc vapor exposure time
Increasing travel speed reduces the time the arc dwells over zinc-coated areas, allowing zinc vapors to escape before the weld pool solidifies and causing less porosity.
Question 4: When oxyfuel welding (OFW) is performed with a neutral flame, what is the ratio of oxygen to acetylene?
- 0.5:1 (excess acetylene)
- 1:1 (equal volumes) (Correct answer)
- 1.5:1 (excess oxygen)
- 2:1 (strongly oxidizing)
Correct answer: 1:1 (equal volumes)
A neutral flame uses a 1:1 ratio of oxygen to acetylene, producing complete combustion with neither excess oxygen nor excess acetylene.
Question 5: What is the purpose of slope-in (upslope) and slope-out (downslope) controls on a GTAW power source?
- They adjust the shielding gas pre-flow and post-flow times
- They gradually increase or decrease welding current at the start and end of the weld to prevent arc craters and burn-through (Correct answer)
- They control the high-frequency arc starting intensity
- They regulate the cooling water flow to the torch
Correct answer: They gradually increase or decrease welding current at the start and end of the weld to prevent arc craters and burn-through
Upslope ramps current up at weld start to avoid cold starts and burn-through on thin metals, while downslope gradually reduces current at weld end to fill and avoid crater cracks.
Question 6: In resistance spot welding (RSW), which factor primarily determines nugget diameter?
- Electrode tip diameter and applied force (Correct answer)
- Base metal thickness only
- Shielding gas composition
- Polarity of the welding current
Correct answer: Electrode tip diameter and applied force
Nugget diameter in RSW is primarily governed by electrode tip diameter (which concentrates current) and electrode force (which controls contact resistance and heat generation).
Question 7: Which AWS process classification letter designation identifies friction stir welding?
- FSW (Correct answer)
- FRW
- RW
- EBW
Correct answer: FSW
AWS designates friction stir welding as FSW; it is a solid-state process that uses a rotating tool to generate frictional heat and plasticize the base metal without melting it.
AWS AWS Welding Processes & Equipment 5
What is the main advantage of electroslag welding (ESW) compared to conventional arc welding processes for thick plate joints?