AWS AWS Welding Processes & Equipment 1 — Questions and Answers
Question 1: In GMAW (MIG welding), what is the primary function of the shielding gas?
- To preheat the base metal
- To protect the molten weld pool from atmospheric contamination (oxygen and nitrogen) (Correct answer)
- To increase the arc voltage
- To serve as a flux carrier
Correct answer: To protect the molten weld pool from atmospheric contamination (oxygen and nitrogen)
Shielding gas in GMAW protects the weld pool from oxygen and nitrogen in the atmosphere, preventing porosity and oxidation.
Question 2: Which SMAW electrode coating type produces a low-hydrogen deposit and requires storage in a rod oven?
- E6010 (cellulosic)
- E6013 (rutile)
- E7018 (low-hydrogen iron powder) (Correct answer)
- E6011 (cellulosic AC/DC)
Correct answer: E7018 (low-hydrogen iron powder)
E7018 is a low-hydrogen electrode that must be kept dry (stored in a rod oven at 250–300°F) to prevent moisture pickup and hydrogen-induced cracking.
Question 3: In GTAW (TIG welding), what does 'AC' current provide when welding aluminum?
- Deep penetration into the base metal
- Cleaning action that breaks up the aluminum oxide layer on the DCEP half-cycle (Correct answer)
- Higher deposition rate than DCEN
- Reduced arc instability
Correct answer: Cleaning action that breaks up the aluminum oxide layer on the DCEP half-cycle
The DCEP half-cycle of AC current provides a cathodic cleaning action that blasts away the tenacious aluminum oxide layer, enabling fusion.
Question 4: What is the primary advantage of FCAW (Flux-Cored Arc Welding) over solid wire GMAW?
- No shielding gas is ever required
- Higher deposition rates and improved performance on rusty or dirty steel (Correct answer)
- Lower heat input than GMAW
- Produces no spatter
Correct answer: Higher deposition rates and improved performance on rusty or dirty steel
FCAW provides higher deposition rates than solid wire GMAW and the flux core provides better tolerance for surface contaminants.
Question 5: In SAW (Submerged Arc Welding), the arc is submerged beneath:
- Water
- A layer of granular flux (Correct answer)
- A dense shielding gas mixture
- Molten slag from the previous pass
Correct answer: A layer of granular flux
In SAW, the arc and weld pool are completely covered by granular flux, which melts to form a protective slag and suppresses arc radiation and spatter.
Question 6: Which welding process uses a non-consumable tungsten electrode and is best suited for precision welding of thin materials?
- SMAW
- GMAW
- GTAW (Correct answer)
- FCAW
Correct answer: GTAW
GTAW (TIG welding) uses a non-consumable tungsten electrode and provides precise heat control, making it ideal for thin materials and critical applications.
AWS AWS Welding Processes & Equipment 1
In GMAW (MIG welding), what is the primary function of the shielding gas?