What type of welding uses a pool of molten metal to join base metals?

Arc welding is recognized for its use of a pool of molten metal, which is created through the application of an electric arc between the electrode and the base metals. This process involves generating sufficient heat to melt the metal at the joint, allowing it to fuse together as it cools and solidifies. The molten metal pool is crucial for achieving strong welds, as it ensures proper fusion between the base metals.

In contrast, spot welding relies on applying pressure and heat to the surfaces of the metals without creating a considerable pool of molten metal that flows around the joint. Oxy-fuel welding combines oxygen and fuel gas to produce a flame that melts the joint area, but it does not involve the same method of creating an electric arc to maintain a sustaining molten pool. Laser welding uses focused laser beams for precise and localized melting but not a molten pool in the same sense as arc welding. Thus, the nature of creating a significant pool of molten metal uniquely identifies arc welding in this context.