SAW Flux Types & Wire Selection 1 — Questions and Answers
Question 1: What are the three main manufacturing categories of SAW flux based on production method?
- Active, neutral, and basic
- Fused, bonded, and agglomerated (Correct answer)
- Ceramic, metallic, and mineral
- High-silica, low-silica, and neutral
Correct answer: Fused, bonded, and agglomerated
SAW fluxes are classified by manufacturing method as fused (melted and re-solidified), bonded (mixed with a binder and dried), and agglomerated (bonded at low temperature, allowing alloying additions).
Question 2: What is the primary advantage of agglomerated (bonded) SAW flux compared to fused flux?
- Lower moisture absorption in storage
- Alloying elements and deoxidizers can be incorporated into the flux (Correct answer)
- Higher melting point for deep-groove welds
- Better slag detachability on flat welds
Correct answer: Alloying elements and deoxidizers can be incorporated into the flux
Agglomerated flux is manufactured at low temperatures that preserve reactive alloying additions, allowing weld deposit chemistry to be adjusted through the flux itself.
Question 3: According to AWS A5.17, what does the 'K' suffix in the wire classification 'EM12K' indicate?
- Korean manufacturing standard compliance
- Killed steel (fine-grain, aluminum-deoxidized) (Correct answer)
- Potassium-stabilized arc characteristics
- Kilogram-rated tensile strength specification
Correct answer: Killed steel (fine-grain, aluminum-deoxidized)
In AWS A5.17, the 'K' suffix designates a killed steel electrode, meaning it is fine-grain, aluminum-deoxidized, which improves toughness and consistency of the weld deposit.
Question 4: What is the recommended practice for storing opened bags of SAW flux to prevent moisture-related weld defects?
- Store at room temperature in the original packaging
- Store in heated ovens at 250–300°F (120–150°C) until use (Correct answer)
- Freeze at 32°F (0°C) to halt chemical reactions
- Store at 100°F (38°C) regardless of manufacturer recommendations
Correct answer: Store in heated ovens at 250–300°F (120–150°C) until use
Opened SAW flux must be kept in heated storage ovens at 250–300°F to drive off moisture; absorbed moisture causes porosity and can introduce hydrogen leading to underbead cracking.
Question 5: A 'neutral flux' in SAW welding is best defined as one that:
- Has a Basicity Index (BI) of exactly 1.0
- Does not significantly change weld metal Mn or Si content as arc voltage varies (Correct answer)
- Contains no alloying elements of any kind
- Produces chemically neutral pH slag after solidification
Correct answer: Does not significantly change weld metal Mn or Si content as arc voltage varies
A neutral flux maintains consistent weld metal manganese and silicon chemistry regardless of voltage changes, making weld chemistry predictable and stable across a range of parameters.
Question 6: For single-wire SAW on plate thicknesses of 1/2" to 1" (12–25 mm), which wire diameter range is most commonly specified?
- 1/16" to 3/32" (1.6–2.4 mm)
- 3/32" to 5/32" (2.4–4.0 mm) (Correct answer)
- 5/32" to 3/16" (4.0–4.8 mm)
- 3/16" to 1/4" (4.8–6.4 mm)
Correct answer: 3/32" to 5/32" (2.4–4.0 mm)
Wire diameters of 3/32" to 5/32" are standard for medium plate thicknesses, providing adequate deposition rates while remaining controllable at the required current levels.
Question 7: The 'flux consumption ratio' used in SAW welding job planning is defined as:
- The ratio of flux melted to flux recovered after welding
- The weight of flux consumed per weight of wire electrode consumed (Correct answer)
- The percentage of flux that converts to slag versus weld metal
- The ratio of active flux blended with neutral flux
Correct answer: The weight of flux consumed per weight of wire electrode consumed
Flux consumption ratio (typically 1:1 to 1.5:1 lb flux per lb wire) compares flux consumed to wire consumed by weight, allowing accurate flux quantity estimation for a job.
