AWS AWS Welding Processes & Equipment 2 — Questions and Answers
Question 1: What does 'duty cycle' mean for a welding power source?
- The maximum amperage the machine can produce
- The percentage of a 10-minute period that the machine can operate at a rated amperage without overheating (Correct answer)
- The voltage output range of the machine
- The number of welding passes the machine can produce per hour
Correct answer: The percentage of a 10-minute period that the machine can operate at a rated amperage without overheating
Duty cycle is the percentage of a 10-minute period (or sometimes 100 seconds in some standards) a machine can weld at its rated output without exceeding temperature limits.
Question 2: In GMAW, 'short-circuit transfer' (short-arc) metal transfer is best suited for:
- Thick plate overhead welding at high amperages
- Thin gauge material and out-of-position welding at low heat input (Correct answer)
- High deposition rate flat-position welding only
- Aluminum welding with argon shielding
Correct answer: Thin gauge material and out-of-position welding at low heat input
Short-circuit transfer uses low voltage and amperage, producing a small, fast-freezing weld pool ideal for thin material and out-of-position welding.
Question 3: Which polarity is used with an E6010 SMAW electrode for maximum penetration?
- AC (alternating current)
- DCEN (direct current electrode negative)
- DCEP (direct current electrode positive) (Correct answer)
- High-frequency AC
Correct answer: DCEP (direct current electrode positive)
E6010 uses DCEP (reverse polarity), which concentrates 2/3 of the heat at the electrode and provides deep penetration.
Question 4: What is the purpose of 'wire feed speed (WFS)' in GMAW?
- It controls the shielding gas flow rate
- It controls the rate at which electrode wire is fed to the arc, which determines amperage (Correct answer)
- It controls the travel speed of the welding torch
- It regulates the pre-flow of shielding gas
Correct answer: It controls the rate at which electrode wire is fed to the arc, which determines amperage
Wire feed speed determines how fast the consumable wire is fed into the arc, which in turn controls the welding current (amperage).
Question 5: A 'constant voltage (CV)' power source is primarily used with which welding process?
- SMAW
- GTAW
- GMAW and FCAW (Correct answer)
- OFW
Correct answer: GMAW and FCAW
Constant voltage (CV) power sources are designed for continuous wire feed processes like GMAW and FCAW, providing self-regulation of arc length.
Question 6: In GTAW, what is the purpose of 'back-purging' when welding stainless steel or titanium pipe?
- To preheat the pipe interior before welding
- To flood the inside of the pipe with inert gas, preventing oxidation of the root weld (Correct answer)
- To cool the pipe faster after welding
- To remove moisture from the pipe interior
Correct answer: To flood the inside of the pipe with inert gas, preventing oxidation of the root weld
Back-purging fills the pipe interior with argon or nitrogen to protect the weld root from atmospheric oxidation during GTAW.
AWS AWS Welding Processes & Equipment 2
What does 'duty cycle' mean for a welding power source?