TABLE OF CONTENTS Materials joining technologies cover a very wide range of manufacturing processes to assemble products by connecting and uniting component parts. Materials joining processes are generally divided into the following groups: mechanical fastening, adhesive bonding, solid-state welding, brazing and soldering, and fusion welding. Chapters 33 and 34 are concerned only with those processes in which materials are joined through the formation of primary chemical bonds under the combined action of heat and pressure, i.e. welding, brazing and soldering.
In theory, two ideal metallic surfaces that are both perfectly clean and atomically flat will bond together if brought into intimate contact: they will be drawn together spontaneously by the interatomic forces until the distance separating them corresponds to the equilibrium interatomic spacing. In practice, surface oxides or other contaminants and surface roughness act to effectively prevent spontaneous bonding. Heat, pressure and/or other engineering measures are therefore required to encourage the formation of a metallurgical joint. There are three major types of materials joining mechanisms: solid-state welding, brazing/soldering, and fusion welding. Solid-state welding is achieved by deformation where no melting occurs; therefore, by definition, solid-state welding occurs at temperatures lower than the melting point of the metals to be joined. Fusion welding and brazing/soldering are achieved by local melting and epitaxial solidification. In brazing/soldering, only the melting of filler metals occurs (in initial stages at least) whereas fusion welding entails transient melting of some base metal in addition to any added filler metal.
A partial list of welding, brazing...
