Brazing is used to join metal parts of the same or different materials together in fixed joints (joint brazing) or to provide the material with a metallic coating.

When brazing the braze joint is heated to the operating temperature of the solder or slightly higher. Since the operating temperature is always lower and usually considerably lower than the melting temperature of the base material, this will remain in solid state during the whole brazing process. If the joint surfaces are sufficiently clean, the molten solder will wet the surfaces causing a diffusion between the solder and the joint surfaces. In this way, the solder and the base material of the joint surfaces alloys with each other in a narrow zone (called bonding zone) nearest to the respective joint surface.

Ref. Karlebo Handbok