Heating a weld to the point of melting is referred to as?

Fusion welding refers to a process where materials are heated to their melting point in order to join them together. This method relies on the principles of molecular bonding at the atomic level, creating a strong joint when the molten metal cools and solidifies. In fusion welding, the heat may be supplied by different means such as an electric arc, gas flame, or other energy sources. The essence of this process is the complete melting of the base materials, which allows for a homogenous blend of the metals being joined.

In contrast, the other welding methods listed do not focus specifically on the complete melting of the base materials. Arc welding, for instance, can be a type of fusion welding but may have specific techniques and variations that don't exclusively describe the melting process itself. Spot welding and resistance welding are typically used for joining smaller or thinner materials and operate on different principles that don't involve complete melting of the base metals. Spot welding creates a weld at specific points without melting the entire structure, while resistance welding uses electrical resistance to generate heat at the joining area without necessarily achieving a full melt.