In GTAW, what does the term "heat affected zone" refer to?

The term "heat affected zone" (HAZ) in GTAW refers specifically to the region that has undergone changes in its mechanical properties due to exposure to the heat generated during the welding process. When metal is heated, it can experience alterations in its microstructure, which can affect characteristics such as hardness, strength, and ductility. This zone extends beyond the actual weld bead and encompasses the adjacent base material that was affected by the elevated temperatures.

Understanding the HAZ is crucial for weld integrity and performance, as it can lead to weaknesses in the material if not properly managed. The considerations of the HAZ are essential for welders to ensure the quality and durability of the weld, as well as to prevent defects that may arise from unintended changes in the material's properties during welding.