AWS Gas Tungsten Arc Welding (GTAW/TIG) Fundamentals 5

Question 1

In GTAW, what is the primary function of the foot pedal or fingertip amperage control?

Accepted Answer

To vary the welding current in real time, allowing control of heat input

Answer

Amperage controls let the welder reduce heat input at the end of a weld or on thin sections, preventing burn-through and crater cracking.

Question 2

What type of joint preparation is generally preferred for GTAW butt welds on base metal thicker than 3/16 inch (4.8 mm)?

Accepted Answer

Single-V or double-V groove to allow full penetration

Answer

Groove preparations like the V-groove open the joint so the narrow GTAW arc can achieve complete joint penetration in thicker materials.

Question 3

Which shielding gas mixture is often used in GTAW of carbon and low-alloy steels to improve arc stability and increase travel speed?

Accepted Answer

Argon with 2–5% hydrogen

Answer

Small hydrogen additions increase arc voltage and heat input, improving travel speed and penetration on austenitic stainless and some steel applications.

Question 4

What welding defect is most likely caused by insufficient post-weld gas coverage (post-flow) in GTAW?

Accepted Answer

Oxidation and discoloration of the weld and heat-affected zone

Answer

Without adequate post-flow, the hot tungsten and weld metal are exposed to atmosphere, causing oxidation that appears as discoloration and can compromise corrosion resistance.

Question 5

In AWS GTAW qualification testing, what is the significance of a 'guided bend test'?

Accepted Answer

It evaluates weld ductility and soundness by bending a coupon around a mandrel of specified diameter

Answer

Guided bend tests reveal internal discontinuities and assess ductility; coupons must not crack beyond the allowable limits to pass AWS qualification.

AWS Practice Test

AWS Practice Test

AWS Gas Tungsten Arc Welding (GTAW/TIG) Fundamentals 5