Flux Types & Wire Selection Flashcards
7 cards from real SAW practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Flux Types & Wire Selection flashcards as text
What effect does increasing arc voltage have on SAW weld bead geometry?
Answer: Increases bead width and decreases penetration
Higher arc voltage lengthens the arc column, spreading heat laterally to produce a wider, flatter bead with reduced depth of fusion into the base metal.
When selecting SAW wire for low-alloy high-strength steel, what is the primary consideration for maintaining weld metal toughness?
Answer: Controlling carbon equivalent and matching alloy additions (Ni, Mo) to base metal requirements
Weld metal toughness on high-strength steels depends on controlled carbon equivalent and appropriate alloy additions; the wire chemistry must be matched to the required mechanical properties.
In a tandem SAW setup, what is the typical polarity arrangement for lead and trail electrodes?
Answer: Lead electrode DCEP for penetration; trail electrode DCEN or AC for deposition
Tandem SAW optimizes each wire independently: the lead wire uses DCEP for deep penetration to achieve fusion, while the trail wire uses DCEN or AC to maximize deposition rate and shape the bead.
Compared to DCEP (electrode positive), using DCEN (electrode negative) polarity in SAW produces:
Answer: Lower penetration and higher deposition rate
With DCEN, more heat is generated at the electrode tip rather than the base metal, melting more wire per unit time (higher deposition) while reducing fusion depth (lower penetration).
In the AWS A5.17 flux-wire classification 'F7A2-EM12K', what does the 'F7' prefix indicate about the weld deposit?
Answer: Minimum tensile strength of 70,000 psi (70 ksi)
In AWS A5.17, 'F7' designates a flux that, when used with the specified wire, produces weld metal with a minimum 70,000 psi tensile strength; the number represents tensile strength in multiples of 10,000 psi.
What does the 'A2' designator in the AWS A5.17 classification 'F7A2-EM12K' specify?
Answer: As-welded condition with minimum 20 ft-lb CVN impact toughness at −20°F
'A' indicates the as-welded condition (no post-weld heat treatment), and '2' specifies the Charpy V-Notch test temperature as −20°F with a minimum 20 ft-lb impact requirement.
Why is controlling electrode extension (contact-tip-to-work distance) important in SAW welding?
Answer: Extension affects resistive preheating of the wire, altering deposition rate and arc current
The wire between the contact tip and the arc acts as a resistor; longer extension increases resistive heating, which raises deposition rate but reduces current for the same wire feed speed, altering penetration.