456A GTAW TIG

Question 1

What type of electrode is used in GTAW (TIG) welding and why is it called 'non-consumable'?

Accepted Answer

A tungsten electrode that creates the arc but does not melt into the weld pool; it is 'non-consumable' because it has a much higher melting point than the base metal

Answer

A coated steel electrode that melts into the weld

Answer

A copper electrode that conducts electricity

Answer

A ceramic electrode that provides shielding

Question 2

What shielding gas is most commonly used in GTAW welding?

Accepted Answer

Pure argon (100%) or argon-helium mixtures

Answer

Carbon dioxide (CO₂)

Answer

Nitrogen

Answer

Oxygen

Question 3

What polarity is used for GTAW welding of carbon steel and stainless steel?

Accepted Answer

DCEN (DC Electrode Negative / Straight Polarity) for maximum penetration and minimal electrode heating

Answer

DCEP (Reverse Polarity)

Answer

AC only

Answer

Any polarity works equally well

Question 4

Why is AC polarity used for GTAW welding of aluminium?

Accepted Answer

The electrode-positive (EP) half-cycle provides a cathodic cleaning action that breaks up the aluminium oxide layer, while the electrode-negative (EN) half-cycle provides penetration

Answer

AC is cheaper to generate

Answer

AC prevents the aluminium from melting too fast

Answer

AC is required by the aluminium welding code

Question 5

What is the purpose of post-flow gas in GTAW welding?

Accepted Answer

To continue shielding the cooling tungsten electrode and weld pool after the arc is extinguished, preventing oxidation

Answer

To cool the weld pool faster

Answer

To clean the gas lines after welding

Answer

To test the gas flow rate

Question 6

What is the correct method for preparing (grinding) a tungsten electrode for DC welding?

Accepted Answer

Grind it to a tapered point along the length axis (longitudinal grinding) with the grinding marks running lengthwise, not across the tip

Answer

Grind it flat

Answer

Break it to create a sharp point

Answer

No preparation is needed — use as-received