20 GMAW & FCAW (MIG / Flux Core) Practice Questions & Answers

1. 1. GMAW and FCAW wire feeders are paired with a constant-voltage (CV) power source rather than a constant-current one. What does a CV output do for a continuously fed electrode?

   • A.It holds welding current nearly fixed so arc length stays the same however the gun is moved
   • B.It caps short-circuit current so the wire can never fuse itself into the contact tip
   • C.It holds arc voltage nearly fixed and lets current vary, so the wire burns off as fast as it is fed✓ Answer
   • D.It raises voltage as the arc lengthens, pushing the puddle down and reseating the electrode

   A constant-voltage machine holds arc voltage roughly steady and lets the current float, so the burnoff rate automatically matches the wire feed speed. That self-regulation is what a continuously fed electrode needs; constant-current output belongs to SMAW and GTAW, where the operator sets arc length by hand.

   Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

2. 2. During a GMAW weld the welder's hand drifts closer to the plate, briefly shortening the electrode extension. On a constant-voltage machine, what happens next?

   • A.The current rises, the wire melts off faster, and the arc length returns to its preset value✓ Answer
   • B.The current drops, the wire melts more slowly, and the arc stretches until the wire stubs into the plate
   • C.The voltage climbs to compensate and the feeder automatically slows the wire down to match
   • D.Nothing changes, since the current is fixed and only the operator can reset the arc length

   Shortening the electrode extension lowers the resistance of the stickout, so the constant-voltage source pours out more current; the higher current burns the wire off faster until the preset arc length is re-established. This self-regulating burnoff is why arc length recovers without the welder touching a knob.

   Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

3. 3. On a GMAW machine set up to a WPS, which welding output does the wire feed speed control actually set?

   • A.The inductance, because faster wire needs a softer short-circuit response
   • B.The arc voltage, because faster wire shortens the arc and pulls the voltage down
   • C.The welding current, because more amperage is drawn to melt the extra wire✓ Answer
   • D.The travel speed, because the puddle has to keep pace with the wire arriving

   On a constant-voltage machine the operator does not set amperage directly: the current settles at whatever value is needed to melt the wire at the speed it is fed, so turning wire feed speed up raises the current. Voltage is the separate knob, and it governs arc length and bead shape.

   Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

4. 4. A welder raises the voltage setting on a GMAW machine and changes nothing else. What happens to the arc and the bead?

   • A.The arc lengthens and the bead becomes narrower and more crowned
   • B.The arc lengthens and the bead becomes wider and flatter✓ Answer
   • C.The arc shortens and the bead becomes narrower and more crowned
   • D.The arc shortens and the bead becomes wider and flatter

   Voltage is the arc-length control on a constant-voltage machine: more voltage means a longer arc, and a longer arc spreads its cone over more of the joint, so the bead washes out wider and flatter with less crown. Too much of it eventually brings undercut and a loss of gas coverage.

   Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

5. 5. Which statement describes short-circuiting transfer in GMAW?

   • A.Drops much larger than the wire fall across the gap by gravity alone
   • B.The wire dips into the puddle and shorts many times a second, giving low heat✓ Answer
   • C.The wire never touches the puddle and metal crosses as a fine mist
   • D.The current alternates between two levels so each cycle frees one drop

   In short-circuiting transfer the electrode actually touches the puddle and extinguishes the arc many times a second, and metal moves across only during those shorts. That gives the lowest heat input of the GMAW modes, which is what makes thin sheet and out-of-position work possible, but the low heat also makes cold lap and incomplete fusion the mode's characteristic defect.

   Source: AWS A3.0, Standard Welding Terms and DefinitionsReport a problem with this question

6. 6. Why is globular transfer usually regarded as the least desirable GMAW transfer mode?

   • A.Drops bigger than the wire fall by gravity, so spatter is heavy and work stays flat✓ Answer
   • B.The arc is so cold that fusion never occurs and every bead sits on the surface
   • C.It forms only under pure argon, which is far too costly to run on carbon steel
   • D.It demands a constant-current machine, which no standard wire feeder can be matched to

   In globular transfer the droplet grows larger than the wire diameter before gravity pulls it loose, so the transfer is erratic, spatter is the heaviest of any mode, and the big falling drop cannot be controlled out of position. It is essentially a flat-position-only mode with poor bead appearance.

   Source: AWS A3.0, Standard Welding Terms and DefinitionsReport a problem with this question

7. 7. Axial spray transfer is normally restricted to which welding positions?

   • A.Vertical and overhead welds, since the fine droplets are carried up against gravity
   • B.Flat groove welds and horizontal fillets, since the puddle is large and fluid✓ Answer
   • C.Overhead welds only, since the high current keeps the puddle from dripping
   • D.All positions, since the arc force by itself holds the puddle in the joint

   Spray transfer runs at high current and deposits a great deal of metal quickly, so the puddle is broad and very fluid and gravity simply drains it out of a vertical or overhead joint. That confines it to flat groove welds and horizontal fillet welds; pulsed spray exists precisely to get spray-type transfer out of position.

   Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

8. 8. Which shielding gas will support true axial spray transfer on carbon steel?

   • A.100% carbon dioxide, whose extra arc heat drives droplets across
   • B.A mostly-argon mixture, such as 90% argon with 10% carbon dioxide✓ Answer
   • C.A 50/50 blend of argon and carbon dioxide, the usual mixture for spray
   • D.100% helium, because it is the most inert of the shielding gases

   Axial spray only forms above a transition current in an argon-rich atmosphere, because argon gives the constricted, stable arc column that pinches off the fine droplets. Carbon dioxide is a reactive gas that broadens and destabilizes the arc, so a carbon-dioxide-rich shield produces globular transfer no matter how high the current goes.

   Source: AWS A5.18, Specification for Carbon Steel Electrodes and Rods for Gas Shielded Arc WeldingReport a problem with this question

9. 9. What is the main reason a shop selects pulsed spray transfer (GMAW-P) instead of conventional spray?

   • A.It lets a constant-current machine be run with an ordinary constant-speed feeder
   • B.It removes the need for shielding gas, since the pulses form their own shield
   • C.It lays a slag blanket over the bead that slows cooling and refines the metal
   • D.It gives spray-like transfer at lower average heat, opening thin and out-of-position work✓ Answer

   Pulsed spray switches between a background current too low to transfer metal and a peak above the transition current that detaches one droplet per pulse. Averaged over time the heat input is far below straight spray, so the puddle stays controllable on thin material and in vertical and overhead joints while keeping spray's clean, spatter-free transfer.

   Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

10. 10. Compared with a 75% argon / 25% carbon dioxide blend, what does welding carbon steel on 100% carbon dioxide give?

    • A.Deeper penetration with almost no spatter and a very smooth bead face
    • B.Shallower penetration with a softer arc and noticeably less spatter
    • C.Deeper penetration with a harsher arc and noticeably more spatter✓ Answer
    • D.The same penetration, but with a fully inert and non-reactive shield

    Carbon dioxide dissociates in the arc and takes heat with it, producing a broad, deeply digging and comparatively violent arc, so penetration goes up and so does spatter. The argon in a 75/25 blend steadies the arc and calms the transfer, which is why it is preferred where bead appearance and out-of-position control matter.

    Source: AWS A5.18, Specification for Carbon Steel Electrodes and Rods for Gas Shielded Arc WeldingReport a problem with this question

11. 11. What does adding helium to an argon shielding gas mixture do?

    • A.It cools the arc, so thin sheet can be welded with no risk of burn-through
    • B.It raises the arc heat, widening and deepening the penetration profile✓ Answer
    • C.It makes the mixture heavier than air, so much less flow is needed for cover
    • D.It puts oxygen into the arc, which steadies it and improves wetting on steel

    Helium has a much higher thermal conductivity and ionization potential than argon, so a helium addition makes a hotter, broader arc that puts more energy into the joint. That is why argon-helium mixtures are used on thick sections and on metals that pull heat away fast, such as aluminum and copper.

    Source: AWS A5.32, Specification for Welding Shielding GasesReport a problem with this question

12. 12. Why is aluminum welded on argon or an argon-helium mixture rather than a blend containing carbon dioxide?

    • A.Carbon dioxide is lighter than air and blows off the puddle before it can shield it
    • B.Carbon dioxide freezes at the low currents used on aluminum and plugs the gas nozzle
    • C.Carbon dioxide will not carry the high frequency that aluminum wire feeding requires
    • D.Carbon dioxide is reactive, and its oxygen would leave the weld oxidized and porous✓ Answer

    Aluminum forms a tenacious oxide almost instantly, so it must be welded under a truly inert shield. Carbon dioxide is a reactive gas that breaks down in the arc and releases oxygen, which would oxidize the puddle and leave a dirty, porous, weak weld, so only argon or argon-helium is used.

    Source: AWS A5.32, Specification for Welding Shielding GasesReport a problem with this question

13. 13. A welder doubles the shielding gas flow to fight porosity and the porosity gets worse. What explains that?

    • A.The regulator reads high flow as a leak and cuts gas at each arc start
    • B.The higher flow strips deoxidizers from the wire before the puddle
    • C.The faster stream turns turbulent and pulls surrounding air into the shield✓ Answer
    • D.The extra gas chills the puddle so fast that trapped gas cannot escape

    Shielding works only while the gas leaves the nozzle in smooth laminar flow. Past a certain rate the stream becomes turbulent, and turbulence aspirates the surrounding atmosphere into the envelope, so nitrogen and oxygen reach the puddle and porosity increases. Too little flow and too much flow produce the same defect.

    Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

14. 14. ER70S-6 is chosen over ER70S-3 for shop work on plate that still carries mill scale. What makes ER70S-6 the better choice?

    • A.It is a tubular wire whose flux floats mill scale up out of the molten puddle
    • B.It is rated at a higher tensile strength, which plate carrying mill scale calls for
    • C.It runs on straight polarity, which burns contamination off ahead of the arc
    • D.It carries more silicon and manganese deoxidizers, so it handles scale better✓ Answer

    Both wires are solid carbon steel electrodes with the same 70,000 psi minimum tensile class; the final digit is a composition and usability designator. The 6 carries higher silicon and manganese, which are deoxidizers that tie up oxygen from scale and rust, so the wire wets out flatter on less-than-clean plate.

    Source: AWS A5.18, Specification for Carbon Steel Electrodes and Rods for Gas Shielded Arc WeldingReport a problem with this question

15. 15. In the flux cored electrode classification E71T-1, what does the 1 that follows the 7 tell the welder?

    • A.The electrode takes one shielding gas, carbon dioxide
    • B.The electrode is limited to the flat and horizontal positions
    • C.The electrode is approved for single-pass welding only
    • D.The electrode may be used in all welding positions✓ Answer

    In the carbon steel flux cored classification the digit after the strength designator is the position digit: 1 means all positions, and 0 in that slot means flat and horizontal only. The T identifies a tubular electrode and the suffix after the dash is the usability designator that fixes shielding and polarity.

    Source: AWS A5.20, Specification for Carbon Steel Electrodes for Flux Cored Arc WeldingReport a problem with this question

16. 16. Why is self-shielded flux cored welding (FCAW-S) the usual pick for outdoor field work?

    • A.It uses a small gas cylinder that a welder can carry on a belt to the work
    • B.Its slag is thick enough that it can be run in rain with no porosity risk
    • C.Its core makes the shielding itself, so wind has no gas envelope to blow away✓ Answer
    • D.It runs on constant current, so an engine drive can power the gun directly

    In FCAW-S the flux ingredients inside the tubular wire decompose in the arc and generate the shielding atmosphere and slag on the spot, so there is no external gas envelope for a breeze to displace. Gas-shielded processes lose their shield in even a light wind, which is why codes limit wind velocity in the weld area.

    Source: AWS D1.1, Structural Welding Code - SteelReport a problem with this question

17. 17. Flux cored welds are made with a drag (backhand) travel angle instead of a push. Why?

    • A.Dragging keeps the molten slag behind the arc instead of rolling it into the joint✓ Answer
    • B.Dragging widens the bead and flattens its face, which the slag cannot do alone
    • C.Dragging lowers the arc current, which keeps the tubular wire from overheating
    • D.Dragging sends the shielding gas ahead of the puddle to preheat the base metal

    Flux cored wire always produces slag, and slag floats on the puddle. A drag angle points the arc back over metal already deposited and leaves the slag trailing, while a push angle rolls the slag forward ahead of the arc where it gets buried by the next metal, giving slag inclusions and lack of fusion.

    Source: AWS A5.20, Specification for Carbon Steel Electrodes for Flux Cored Arc WeldingReport a problem with this question

18. 18. Which drive roll is used to feed tubular flux cored electrode wire?

    • A.A smooth U-groove roll, the standard roll for all cored wire
    • B.A knurled roll, whose teeth grip without crushing the tube✓ Answer
    • C.A smooth V-groove roll, run at high tension for a firm grip
    • D.A flat-faced roll, which spreads the pressure along the wire

    A flux cored wire is a thin steel tube filled with powder, so it crushes far more easily than solid wire. Knurled rolls bite the surface and drive the wire with light pressure, whereas a smooth roll would need enough squeeze to flatten the tube, spill the flux and jam the liner. V-groove rolls suit solid steel wire and U-groove rolls suit soft aluminum wire.

    Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

19. 19. A GMAW welder keeps getting burnback, the wire fusing into the contact tip as the arc ends. Which is a likely cause?

    • A.Wire feed speed set too low for the voltage, letting the arc burn back to the tip✓ Answer
    • B.Wire feed speed set too high for the voltage, driving wire into cold plate
    • C.Work clamp placed too near the arc, which raises the current inside the contact tip
    • D.Shielding gas flow set too high, chilling the tip and freezing the wire in it

    Burnback happens when the wire cannot be fed fast enough to keep the arc down at the work, so the arc climbs the electrode and melts it off against the tip. Feed speed too low for the voltage, too short an electrode extension, a worn or oversized contact tip, and anything that slows feeding all cause it, and a burnback timer setting can trim the tail.

    Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

20. 20. With everything else held constant, what happens when a GMAW welder increases the contact-tip-to-work distance?

    • A.Current falls but penetration deepens, because the arc is more tightly focused
    • B.Current falls and penetration drops, and gas coverage becomes less reliable✓ Answer
    • C.Current holds steady while arc voltage falls, leaving the bead shape unchanged
    • D.Current rises and penetration deepens, and gas coverage becomes more reliable

    A longer stickout puts more electrical resistance in the electrode extension, so the constant-voltage source delivers less current; the wire is preheated by that resistance and deposits faster but with less arc force and shallower penetration. The nozzle is also farther from the joint, so the gas envelope is easier to disturb and porosity risk climbs.

    Source: AWS EG2.0, Guide for the Training of Welding Personnel: SENSE Level I-Entry WeldersReport a problem with this question

Practice questions based on the AWS SENSE Level I (Entry Welder) written modules, ANSI Z49.1 safety practice, and AWS A2.4 welding symbols. This bank covers the KNOWLEDGE half of entry-level welding only — the workmanship and welder performance qualification tests are hands-on and cannot be practised here, and this is not preparation for the separate, performance-based AWS Certified Welder credential. AWS, SENSE, and NCCER are marks of their respective organizations; this site is not affiliated with or endorsed by them. Work from your program's current materials, and follow the welding procedure and drawings on your own job rather than any number you remember. About AWS SENSE →