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Brazing steel


#1

I know that one would braze or as jewelers call it, solder, with
brass. I also know that one would buy the brass in rod form
already coated with flux. My question is – when you braze
steel, how hot are you getting, do you have to apply any flux to
the metal pieces you are joining? Please help

Marshall Jones
@Bob_Jones


#2

I know that one would braze or as jewelers call it, solder, with
brass. I also know that one would buy the brass in rod form
already coated with flux. My question is – when you braze
steel, how hot are you getting, do you have to apply any flux to
the metal pieces you are joining? Please help
Marshall Jones jones@perigee.net

Hi Marshall,

Just as with ‘soldering’ the areas to be joined have to be
cleaned (ground, sanded etc) to grease free bare metal. The fit
does not have to as good as for jewelery purposes. You can braze
(‘solder’) with any metal that melts lower than steel which
includes all silver, copper, gold and brass alloys-ie any strip
of brass from the scrap box can be used. You need a lot of flux,
I usually begin with pouring on my borax type comercial brazing
paste flux, then dusting with powdered borax so it sticks and
doesn’t fly around when I bring the torch to bear on the join. I
usually add powdered borax during heating up as well. The flux
burns out quickly (has to do a lot of work and gets used up).
Steel takes a lot of heat pumped into it to get to orange red (a
good color to braze at). Concentrate the heat on the larger
volume of metal, if you are brazing a small piece to a large
piece do not point the flame at the small piece until the large
piece is very hot, let the heat go from the larger to the smaller
pieces. Scotch-brite (or sand or scrape) the brass rod or strip.
Have it held in long clamping tongs of some kind (steel puts out
a lot of heat when red hot-you will not be able to get your hand
close in), flux the brass and feed it into the join like wire or
stick soldering. Do not move the parts until the red color has
almost died out-brass is brittle when glowing. Do not quench the
steel until it is black in color just in case one of the steel
bits is high carbon and would be hardened and hence embrittled
by quenching. I usually use hot running water to remove flux
residues, some people use a new sparex pickle for this.

Charles

Brain Press
Box 1624, Ste M, Calgary,
Alberta, T2P 2L7, Canada
Tel: 403-263-3955 Fax: 403-283-9053
Email: @Charles_Lewton-Brain

Metals info download web site:
https://www.ganoksin.com/borisat/tip_sear.htm Product descriptions:
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#3

I know that one would braze or as jewelers call it, solder, with
brass. I also know that one would buy the brass in rod form
already coated with flux. My question is – when you braze
steel, how hot are you getting, do you have to apply any flux to
the metal pieces you are joining? Please help

Brazing steel is a little different than jewelry soldering.
First the flame must be a neutral flame not oxidizing nor
reducing. the brazing rod should be flux coated it will act as a
filler. The process is more like fusing than soldering. You must
get your joint molten and then add the brazing material. To my
knowledge you must use acetelyne I don’t think propane will be
hot enough to get the steel into a fluid state. If your joint has
any length to it the direction you hold the torch flame is also
important. Work from left to right with the torch in your left
hand pointed on a 45 degree angle right hold the fluxed rod in
your right hand again at an angle pointed left with a slight
jabbing motion bring the rod into the molten steel but keep it
about a 16th above so the brass drips into it something like wax
dripping off a candle. Don’t flood the joint with brazing metal
add just enough to level the surface.

good luck

steve ross