What is the primary purpose of flux in welding?

The primary purpose of flux in welding is to prevent oxidation of the metals due to heat. When metals are heated during the welding process, there is a significant risk of oxidation occurring, which can adversely affect the quality and integrity of the weld. Flux serves as a protective barrier that shields the molten metal from oxygen and other atmospheric elements. By doing so, it helps maintain a clean weld pool, which is crucial for achieving a strong and durable joint.

While other options reference various aspects of welding, they do not address the core function of flux as effectively. Cleaning welds after the procedure or promoting the creation of slag, while potentially related to aspects of the welding process, do not encompass the fundamental role of preventing oxidation. Preheating the weld is also a separate technique used for managing thermal effects, rather than a function of flux itself.