AWS Gas Tungsten Arc Welding (GTAW/TIG) 2

Question 1

What type of tungsten electrode is most commonly recommended for welding aluminum using AC current in GTAW?

Accepted Answer

Pure tungsten (EWP)

Answer

Pure tungsten (EWP) is traditionally recommended for AC GTAW on aluminum because it forms a balled end that aids in oxide cleaning during the electrode positive half-cycle.

Question 2

In GTAW, what is the primary function of the post-flow shielding gas after the arc is extinguished?

Accepted Answer

Cool the tungsten electrode and protect the solidifying weld pool and hot tungsten from oxidation

Answer

Post-flow shielding gas protects both the hot tungsten electrode and the solidifying weld pool from atmospheric contamination (oxidation and nitridation) until they cool below the temperature at which oxidation occurs.

Question 3

Which shielding gas is most widely used for GTAW on carbon and low-alloy steels?

Accepted Answer

100% Argon

Answer

100% Argon is the most widely used shielding gas for GTAW on carbon and low-alloy steels because it provides stable arc characteristics and adequate shielding at a lower cost compared to helium.

Question 4

What AWS classification covers filler metals used in GTAW of carbon steel?

Accepted Answer

AWS A5.18

Answer

AWS A5.18 covers carbon steel filler metals for gas shielded arc welding, including GTAW rods such as ER70S-2 and ER70S-6.

Question 5

In GTAW, what condition is indicated when the tungsten electrode becomes contaminated with base metal (appears gray or has inclusions)?

Accepted Answer

The electrode dipped into the weld pool

Answer

Tungsten contamination with base metal material occurs when the electrode tip makes contact with (dips into) the molten weld pool, transferring base metal into the tungsten and requiring re-preparation of the electrode.

AWS Practice Test

AWS Practice Test

AWS Gas Tungsten Arc Welding (GTAW/TIG) 2