Difference Between Soldering and Brazing

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I recently reviewed your response regarding the difference between soldering and brazing. Having worked for a manufacturer of brazing and soldering products for 16 years I would like to provide a more accurate explanation of these processes.

AWS American Welding Society defines brazing processes as simply put processes which take place above 840F. Soldering below 840F I join Hard Soldering or silver solder are a slang terms used in industry for years. Silver Brazing alloys are classified by AWS as BAg alloys. B=brazing, Ag=silver. Phos Copper Silver alloys are classified as BCuPB=brazing Cu=copper P=Phosphorous.

It is important to note that industry and OSHA has classified CADMIUM as a potential cancer causing agent. Many cadmium free alloys are available. Solders are typically tin/lead, tin/silver. It is also important to remember that lead solder are not to be used on potable water sustems. Nice informative web site!

The Tin Man Respondeth:

Thank you very much for the infobits. The article is yet unfinished, and my efforts with it are simply to straighten out the very basic "public" information first. These slang terms may remain in use long after both you and I are dust, because the inner dialogues of the industries remain largely unabsorbed by the public at large.

Conventional public terms (slang) are used more readily and easily in daily conversation than more appropriate and more specific engineerspeak. GTAW, GMAW, SMAW, SAW, and HAZ, are routinely discarded in public, favoring TIG, MIG, shielded, stick, and weld area or weld zone.

More to the point, I routinely purchase aluminum "hot bonding alloys" (my term) prominently labeled as: "Soldering, Brazing, and Welding Alloy for aluminum", and sold by say, ESAB. You and I both understand this cannot be, if the MIQ (material in question) melts at 850F, and typical aluminum alloys melt at 1175F, minimum, according to ALCOA. Temperature definitions are not always appropriate, and accasionally, without assistance from other defining states, wholly inaccurate.

One case: I submit to you a zinc-tin-antimony alloy with the melting point established at 825F, and we choose a filler with exactly that melting point, then it appears that we are "welding", because by one definition we are melting the base metal as we fuse in the filler. But by temperature definition? Who can say?

Lead (Pb) welding in the shipyards became known as "lead burning", but was never referred to as soldering, despite the AWS rule for temperature, (475F).

Further complicating my life, are the discussions I've had with the Aluminum Association regarding "Braze-Welding". If you bring me a low-melting aluminum alloy (1175F), and I choose to join it with a like-character aluminum alloy, melting at similar temp, then I am welding.

But, as luck would have it, another guy walks in with a different aluminum alloy, melting at 1425F. I use the same material I did on the first job (melts at 1175F) but now I am brazing, because the filler melts first and bonds by surface adhesion below the melting point of the base metal.

Thank you for your interest and much-appreciated comments,