AWS Gas Metal Arc Welding (GMAW/MIG) 2

Question 1

What metal transfer mode is used in GMAW short-circuit transfer?

Accepted Answer

The wire physically touches and short-circuits into the weld pool at low voltage

Answer

In short-circuit transfer (SCT), the wire tip contacts the molten pool, causing a short circuit; the current surges, melts the wire tip, and breaks the short — repeating 20–200 times per second at low voltage.

Question 2

In GMAW spray transfer, what gas mixture is most commonly used for carbon steel?

Accepted Answer

Ar/CO2 blend (typically 75-95% Ar)

Answer

Spray transfer requires a high-argon shielding gas (typically 75–95% Ar with 5–25% CO2) to maintain the stable axial spray arc; 100% CO2 doesn't support true spray transfer.

Question 3

The 'burnback' setting on a GMAW welding machine controls:

Accepted Answer

The rate at which the wire retracts after the arc extinguishes

Answer

Burnback (also called burn-back time or retract) is the brief delay between wire feed stopping and the power source shutting off, which burns back the wire to prevent it from freezing in the puddle.

Question 4

Globular transfer in GMAW is characterized by:

Accepted Answer

Large, irregular droplets that fall off the wire due to gravity — high spatter

Answer

Globular transfer produces droplets larger than the electrode diameter that detach irregularly due to gravity, resulting in high spatter levels, and is generally avoided in production welding.

Question 5

What is the purpose of the inductance setting on a GMAW CV power source?

Accepted Answer

Smooths the arc by controlling the rate of current rise during short circuits

Answer

Inductance controls how quickly current rises during short-circuit events in GMAW. Higher inductance slows the current rise, producing a softer arc with less spatter and a flatter bead.

AWS Practice Test

AWS Practice Test

AWS Gas Metal Arc Welding (GMAW/MIG) 2