Subject: Re: Need brazing pointers--A second question...

From: [email-masked] (James Kirkpatrick)
Date: 27 Jun 96 08:49:09 MDT

In article <[email-masked]>, [email-masked] (Bernielama) writes:
|>Thanks for the advice! Now, since I want to gain more knowledge about
|>metalworking in general, I have another question. What is the difference
|>between brazing and welding (and soldering, for that matter)? Is brazing
|>more of a surface joint and welding a deeper structural fusion?

You might consider getting the FAQ for this newsgroup and reading it.
It's available via anonymous ftp to plains.uwyo.edu in the metal
directory, or via http://plains.uwyo.edu/~jimkirk

For example, question 21 (in section 4) says, in part --

     There sometimes seems a fine line between soldering (several types,
     at that), brazing, and welding.  Here we try to shed some light on
     soldering and brazing.

     The following was contributed by Tim Kirby around 3/3/93 when the
     newsgroup was discussing the "true meaning" of silver soldering and
     the distinction between hard and soft solder.

     : Can anyone remember the "official" difference between
     : Hard & Soft solders ?

     While browsing for something else entirely, I found my copy of

     'Model Locomotive and Marine Boilers'
     [Argus Press, 1988, ISBN 0-85242-923-1]
      by Martin Evans (well known in the Model Engineering field, at least in
     the UK) from which I have gratuitously (and without prejudice) stolen the
     following extract for your contemplation.  As an aside, this is a useful
     book for those interested in designing and building boilers.

     Chapter 3, page 55: Silver Soldering and Brazing

     Soldering and brazing are processes which involve the joining of metals
     by the addition of molten filler metal of substantially different
     composition, at temperatures well below their melting point.  An important
     difference between silver-soldering and brazing or welding is that the
     brazing alloy or filler material must be drawn by capillary forces right
     through the mating joint surfaces, and not merely deposited at the edges.

     Soft Solders are generally accepted as including the alloys of low melting
     point up to about 400 deg. C.  They are usually based on Tin or Lead with
     small additions of antimony and sometimes silver.

     Hard solders, or silver-solders, are those alloys suitable for soldering
     which have melting points from 400 deg. C. up to about 800 deg. C. (see
     BSI 1845/1964)
    [for those who don't understand that reference, BSI is the British
     Standards Institute, similar in function to (for example) ANSI.
     BSI 1845 probably details this stuff in excruciating detail ;-) ... Tim.]

     Brazing alloys are alloys suitable for brazing (sic) which have melting
     points from about 800 deg. C. up to about 1000 deg. C.

     It should however be understood that there is no definite line of
     demarcation between silver-solders and brazing alloys.  The former always
     contain a proportion of silver, while the brazing alloys generally contain
     copper, zinc and sometimes tin.  Brazing alloys containing copper and
     phosphorus are also available but these are not recommended for boiler
     work.

In contrast, I believe welding implies melting the edges being joined as well
as introducing filler material.

Jim

---

From: [email-masked] (James Kirkpatrick)
Date: 27 Jun 96 14:01:50 MDT

In article <[email-masked]>, [email-masked] (James Kirkpatrick) writes:
|>You might consider getting the FAQ for this newsgroup and reading it.
|>It's available via anonymous ftp to plains.uwyo.edu in the metal
|>directory, or via http://plains.uwyo.edu/~jimkirk
                                           ^^^^^^^^

I apparently typed without engaging brain; make that ~metal

Jim