Soldering and Brazing Soldering is a process in which two or
more metal items are joined together by melting and flowing a
filler metal into the joint, the filler metal having a
relatively low melting point. Soft soldering is characterized by
the melting point of the filler metal, which is below 400 °C
(752 °F). The filler metal used in the process is called solder.
Soldering is distinguished from brazing by use of a lower
melting-temperature filler metal; it is distinguished from
welding by the base metals not being melted during the joining
process. Brazing is a joining process whereby a filler metal or
alloy is heated to melting temperature above 450 °C (840 °F) or,
by the traditional definition in the United States, above 800 °F
(427 °C) and distributed between two or more close-fitting parts
by capillary action. By definition the melting temperature of
the braze alloy is lower (sometimes substantially) than the
melting temperature of the materials being joined. The brazed
joint becomes a sandwich of diff