AWS Gas Tungsten Arc Welding (GTAW/TIG) Fundamentals

Question 1

What type of tungsten electrode is recommended for welding aluminum with GTAW using AC power?

Accepted Answer

Pure tungsten (green band) or zirconiated tungsten (white band)

Answer

For AC GTAW on aluminum, pure tungsten (green) or zirconiated tungsten (white) is preferred because AC's electrode-positive half cycle forms a balled tip that is stable and compatible with these electrode types.

Question 2

The primary advantage of GTAW over SMAW for welding thin stainless steel is:

Accepted Answer

Precise heat control, no slag, and superior weld quality with no contamination

Answer

GTAW provides precise heat control via foot pedal or finger control, produces no slag, uses a non-consumable electrode that doesn't contaminate the weld, and delivers the cleanest possible welds for thin stainless.

Question 3

In GTAW, 'high-frequency (HF) arc initiation' is used to:

Accepted Answer

Initiate the arc without contact between the tungsten and base metal, preventing tungsten contamination

Answer

High-frequency arc initiation ionizes the arc gap between tungsten and base metal, allowing the arc to jump across without the tungsten touching the work — preventing tungsten contamination of the weld.

Question 4

What is the purpose of post-flow (post-purge) in GTAW?

Accepted Answer

Continue shielding gas flow after arc extinguishment to protect the hot tungsten and weld pool from oxidation

Answer

Post-flow continues argon shielding for several seconds after the arc stops, protecting the still-hot tungsten electrode and solidifying weld metal from atmospheric oxygen and nitrogen contamination.

Question 5

The correct tungsten electrode preparation for GTAW DCEN (direct current electrode negative) on carbon steel is:

Accepted Answer

Ground to a sharp point or taper

Answer

For DCEN GTAW, the tungsten should be ground to a sharp taper or point, which concentrates the arc for deep, narrow penetration — the opposite of the balled tip needed for AC.

AWS Practice Test

AWS Practice Test

AWS Gas Tungsten Arc Welding (GTAW/TIG) Fundamentals