AWS Submerged Arc Welding (SAW) 4 — Questions and Answers
Question 1: In SAW, what is the primary purpose of the flux layer covering the arc?
- To preheat the base metal
- To shield the arc and molten pool from atmospheric contamination (Correct answer)
- To increase travel speed
- To reduce electrode consumption
Correct answer: To shield the arc and molten pool from atmospheric contamination
The flux layer completely submerges the arc, protecting the weld from oxygen and nitrogen contamination while also stabilizing the arc.
Question 2: Which SAW parameter has the greatest influence on weld bead width?
- Arc voltage (Correct answer)
- Wire feed speed
- Travel speed
- Electrode polarity
Correct answer: Arc voltage
Arc voltage primarily controls weld bead width in SAW; higher voltage produces a wider, flatter bead.
Question 3: What type of current is most commonly used for single-wire SAW to achieve deep penetration?
- AC with high frequency
- DCEN (electrode negative)
- DCEP (electrode positive) (Correct answer)
- Pulsed AC
Correct answer: DCEP (electrode positive)
DCEP provides the deepest penetration in SAW because more heat is concentrated at the work piece.
Question 4: What is 'flux consumption ratio' in SAW?
- The ratio of flux melted to wire melted by weight (Correct answer)
- The percentage of flux that becomes slag
- The amount of flux needed per pass
- The ratio of active to neutral flux used
Correct answer: The ratio of flux melted to wire melted by weight
Flux consumption ratio (typically 1:1) is the weight of flux consumed relative to the weight of wire consumed during welding.
Question 5: When welding with tandem SAW electrodes, what is the typical relationship between the two arcs?
- Both use DCEP for maximum penetration
- Lead arc uses DCEP for penetration; trail arc uses AC for fill and bead shape (Correct answer)
- Both use AC to minimize arc blow
- Lead arc uses AC; trail arc uses DCEN
Correct answer: Lead arc uses DCEP for penetration; trail arc uses AC for fill and bead shape
Tandem SAW typically uses DCEP on the lead wire for deep penetration and AC on the trailing wire to improve deposition and bead shape while reducing arc blow.
Question 6: What condition causes 'cold cracking' in SAW welds?
- Excessive preheat and high interpass temperature
- High hydrogen content, residual stress, and susceptible microstructure (Correct answer)
- Insufficient flux coverage during welding
- Excessively high arc voltage
Correct answer: High hydrogen content, residual stress, and susceptible microstructure
Cold cracking (hydrogen-induced cracking) requires three factors: diffusible hydrogen, tensile residual stress, and a susceptible (hard) microstructure.
Question 7: Which flux classification system does AWS use for SAW fluxes?
- AWS A5.17 / A5.23 (Correct answer)
- AWS A5.1 / A5.5
- AWS A5.18 / A5.28
- AWS D1.1 / D1.5
Correct answer: AWS A5.17 / A5.23
AWS A5.17 covers carbon steel electrodes and fluxes for SAW, while AWS A5.23 covers low-alloy steel electrodes and fluxes.
AWS Submerged Arc Welding (SAW) 4
In SAW, what is the primary purpose of the flux layer covering the arc?