What are the potential consequences of overheating the base metal in GTAW?

When the base metal is overheated during Gas Tungsten Arc Welding (GTAW), several detrimental effects can occur, leading to burn-through, distortion, and weak welds.

Burn-through happens when excessive heat causes the base metal to melt too quickly, creating holes that compromise the integrity of the material. Distortion can result from the uneven heating and cooling of the metal, leading to warping or bending, affecting the overall alignment and fit-up of components. Additionally, overheating can lead to metallurgical changes within the weld and base metal, which can reduce the strength and durability of the joint. This combination of issues can create a weld that does not meet structural requirements or is prone to failure under stress.

In contrast, improved flow characteristics, increased welding speed, and a better joint appearance are often not achieved through overheating. Instead, good practice in GTAW emphasizes maintaining proper temperature control to achieve high-quality welds that are strong and consistent.