456A TIG (GTAW - Gas Tungsten Arc Welding)

Question 1

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

Accepted Answer

Pure tungsten (EWP) or zirconiated tungsten (EWZr)

Answer

2% thoriated tungsten (EWTh-2)

Answer

Ceriated tungsten (EWCe-2)

Answer

Lanthanated tungsten (EWLa-1)

Question 2

Why is DCEN (Direct Current Electrode Negative) used for most GTAW applications on steel and stainless steel?

Accepted Answer

DCEN concentrates about 70% of the arc heat at the workpiece, providing deep penetration while keeping the tungsten cool

Answer

DCEN provides cathodic cleaning action to remove oxide layers

Answer

DCEN allows higher wire feed speeds for filler metal addition

Answer

DCEN reduces the risk of tungsten contamination

Question 3

What is the purpose of the 'high-frequency (HF) arc start' feature on a GTAW power source?

Accepted Answer

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

Answer

Stabilizes the AC arc by re-igniting it at each zero crossing

Answer

Increases the welding current during the start phase to prevent cold starts

Answer

Activates post-flow shielding gas after the arc is extinguished

Question 4

What shielding gas is standard for GTAW welding of stainless steel?

Accepted Answer

100% Argon

Answer

75% Argon / 25% CO2

Answer

100% Helium

Answer

100% CO2

Question 5

What is 'tungsten inclusion' in GTAW and how is it caused?

Accepted Answer

Tungsten particles embedded in the weld metal; caused by the tungsten tip contacting the weld pool or being contaminated

Answer

Tungsten deposits on the base metal surface from the shielding gas

Answer

Oxidation of the tungsten electrode during welding

Answer

Excessive tungsten electrode consumption during AC welding

Question 6

What is the recommended included angle for grinding a pointed tungsten tip for DCEN GTAW on steel?

Accepted Answer

2.5× the electrode diameter length, ground longitudinally to produce a consistent tip

Answer

Flat (no point) — DCEN requires a flat-ended tungsten

Answer

Blunted to a small flat equal to half the electrode diameter

Answer

Maximum 90° included angle only