I've been trying to figure out the actual differences among
soldering, brazing, and welding. The terms are not used
I helps if you know what industry the speaker is most familiar with.
Sometimes the terms are more or less industry specific.
Soldering in the sheet metal & electronics industries means heating
something with an electric soldering iron or a large copper
soldering iron that's been heated in a fire of some kind, then
applying a 'solder' made usually made of some alloy of tin. It
usually melts around 500F. Fluxes are used.
In the plumbing trade soldering is usually done to copper & brass
usually using a propane fired torch, a flux & a tin based solder
melting around 500F.
Solders used in the previous industries tend to be supplied in a
wire or bar form. In the electronics industry the solder usually
contains a non acid flux. The plumbing & sheet metal trades
generally use a seperate flux, either a liquid, paste or bar.
Soldering in the jewelery trade usually implys using a an alloy of
the metal being soldered (silver, gold, platinum). The alloy usually
melts at a lower temp (but not much) than the material being
soldered. A flux is used to prevent oxide buildups that would hinder
the flow of the molten solder. Solders are available in sheet, wire,
powder & paste. The paste solders usually have a flux mixed in the
In most other metal working industries, this type of 'soldering' is
called 'brazing'. In the ferrous metal industries, the 'solder' used
is generally a brass of some type.
Welding in the non jewelery industries is the joining of multiple
pieces of the same metal by heating them to their melting point
usually with the addition of a filler material of the same metal. In
some cases fluxes are used. The heat may be applied using a gas/oxy
torch, an electric arc, laser or other means.
In the jewelry trade, this method of joining metals is called
Generally, soldering can be differentiated from welding in the way
the connection is made. In soldering, the connection is by means of
a different material that engages the minute surface irregularities
of each piece & upon solidification holds them fast. The material
used as the solder melts at a much lower tgemperature than the
materials being soldered.
Brazing (& jewelery soldering) uses a material that's different (but
in jewelery, not much different) from the materials being brazed.
Typically it melts at a relatively high temperature, but not as high
as the metals being joined. It's method of holding the materials
together is basically the same as for soldering.
Welding however, melts each of the pieces being joined & the molten
materials co-mingle on the atomic level. A filler of the same
material is usually added. In the event that there are small
differences in the makeup of the materials, the welded area is a new
alloy of the materials. However it'd take some sophisticated
analysis to differentiate.
In the jewelery tade this is called 'fusing'. A filler may or may
not be used.
Sometimes soldering is refered to as 'hard' soldering or 'soft'
soldering. Generally, the 'hard' soldering requires a heat over
1000F while 'soft' soldering can be done around 500F. Hard soldering
provides more mechanical strength than soft soldering.
It's also possible to solder & braze dissimilar metals together.
This is very difficult if not impossible by most welding techniques.