What is the function of postflow in GTA welding?

In Gas Tungsten Arc Welding (GTAW), postflow refers to the continued flow of shielding gas after the arc has been extinguished. The primary function of this postflow is to protect the weld pool and surrounding area from oxidation while the material cools.

As the molten weld pool solidifies, it is vulnerable to contamination from atmospheric elements, primarily oxygen. If the weld is exposed to oxygen during this cooling phase, it can lead to defects such as porosity or an overall weakened weld integrity. By maintaining a flow of inert gas (such as argon or helium), the protection of the weld area is ensured, preventing oxidation and helping to achieve a clean and strong weld.

The other choices do not directly pertain to the role of postflow. Enhancing weld depth, controlling welding speed, and improving filler rod placement involve different aspects of the welding process but do not specifically address the purpose of postflow in shielding the weld as it cools.