What is the heat-affected zone (HAZ) in welding, and which GTAW parameters influence its width?

• A. The weld metal only.
• B. A zone outside the weld area with no changes.
• C. The region of base metal whose microstructure is altered by heat; higher heat input and slower travel speed widen the HAZ; material properties and cooling rate also affect it.
• D. The area where shielding gas disappears.

Answer: (C)