Welding and cutting of materials

Article By:

Messler, Robert W., Jr. Materials Research Center, Troy, New York.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.743800

Processes used to atomically join and physically separate materials or structures composed of materials, respectively. As opposed to the other two major processes by which materials and structures are joined—mechanical joining using fasteners or integral design features (that is, integral mechanical attachments) to cause physical interference between parts to create a unit and adhesive bonding to create a unit using chemical adsorption or reaction forces between surfaces of parts—welding relies on the natural tendency of atoms to form bonds with one another as they come into close proximity (Fig. 1). As such, only fundamentally similar materials involving the same type of atomic bonding (for example, ionic, covalent, or metallic) can be caused to join by welding. Although similar or dissimilar metals are most commonly welded, similar or dissimilar glasses, similar or dissimilar thermoplastics, and some similar ceramics (such as some oxides, carbides, and silicides) can also be joined by welding. For atoms to bond to create a weld between two materials or parts, the surfaces must be free of any contaminants and smooth to allow intimate contact (Fig. 2).

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