If there is fusion of the parent metal in a joining process, what is this process designated as?

The process where there is fusion of the parent metal during a joining operation is designated as welding. Welding involves melting the base materials (the parent metals) so that they fuse together upon cooling, forming a permanent joint. This method typically utilizes high heat, often from an electric arc or a flame, to achieve the required temperature for fusing the materials.

In contrast, soldering and brazing are processes that do not involve melting the parent metals; instead, they utilize a filler material that melts at a lower temperature. The filler metal bonds to the base materials without fusing them, thus distinguishing these methods from welding. Joining is a more general term that encompasses all methods of uniting materials, including welding, soldering, and brazing, but it does not specify that fusion of the parent metal occurs.