Hardening and tempering springs
Dick Parsons
Heating the springa and quenching in brine. Then re-heating and quenching
in oil which is then set on fire. When the fire goes out you leave the
spring to cool as usual.
Is this correct?
What oil do I use?
How long should it boil for.
Regards
DickPa
Michael
Dick,
Procedures for hardening, tempering, quenching, and annealing metals can
be found in any edition of the American Machinist's Handbook, editions
of which have been in print since 1908 and are readily available. The
procedure is not so much time related as controlled by temperature which
is judged by the heated color of the metal...not anything that is
exactly intuitive. There are, however, indicator compounds available
that melt at specific temperatures which aid one in determining when
that temperature has been reached. Quite a bit of skill is involved,
including at least a basic knowledge of metalurgy. Thus, I would not
rush into this without study and training.
Regards,
Michael K.
Gary Click
Michael K. is right on course. The purpose of heat treating metal
to obtain spring like properties is to modify the strength
characteristics of the material usually steel. By raising the
yeild/tensile strength of the steel we increase the range of
elastic stress that the steel can exhibit or the amount of
deflection without taking a set or becoming permanently bent
(plastic deformation).
Steels for the most part must have a Carbon content of greater
that .40% to be heatable, common mild steel such as plate bar
angles, etc. typically ranges from .18% to .28%. (this can also
come from other elements as carbon equivalents with the resulting
carbon in the steel being quite low). When the steel is heated
above it's critical temperature there is a molecular
rearrangement that can at high temperatures (2000 F) completely
change the structure to a steel that is nonmagnetic with a
structure called Austenite, this is why common stainless steels
are not magnetic.
Typically steels used for springs transform to a structure called
Martensite at about 1650 F. While the structure is in this phase
the steel is rapidly cooled by quenching in a medium such a
brine, water or oil. This structure is very very strong, as much
as 10 times the strength of the material before heat treatment
and usually quite hard, in the range of 58 to 63 Rockwell C
(drill bit / lathe tool range). If this same steel is allowed to
cool slowly the steel will pass through several phases called
Ferrite, Cementite, Banite, and Peralite and end up as a material
with some of all these phases and usually quite soft, or as we
call annealed.
After the rapid quench the steel is quite hard but extremely
brittle, elongation or the measurement of the amount of bend or
stretch the steel can strand is sometimes less than 1%. The
material won't really work for anything!! The secret lies in
tempering or slightly softening the steel lowering the yield
strength and increasing the ductility and elongation to 20% to
50%. Since reheating to 1600 F would completely soften the steel
we temperature for tempering is much lower in the 500 F range.
This is easily done in your wife oven, if you don't tell her.
With all the theory aside spring making can be as simple or as
difficult as you allow it to be. Machinery' Handbook is perhaps
the best all round technical book written. Stranded on an island
you should only need a Bible and the Handbook to survive. Using
the tables in this book the temperature and quench mediums are
spelled out. Your chances for success will increase dramatically
if you are sure of the alloy you are working with. Other points
that become critical is in the design of the springs being care
to avoid sharp inside corners and other "stress risers" which can
very likely cause the spring to crack in the initial quench.
The most common material but not the best used for springs is
AISI 1080, which is amazingly common. Most common Railroad Rail
produced in the last 40 years in made from the alloy with a
different heat treatment. How many click springs are there in a
yard of 136# rail?
My apologies fro the verbosity.
Gary Click
Watchmender
Thank you for a most interesting and informative exposition of this
subject. It so happens I am today about to do some of this work with a
pocket watch part I made yesterday. I am sure your words will allow
success and avoid my having to make another tomorrow !!!
I wish you both well - we could do with your contributions on my mail
list which is HRSWALESUK also on the CLOCKS list. Do please consider
joining. it's FREE!! <smile>
SAC
======================
In article <3718DDC7...@wwisp.com>, Gary Click
<vani...@wwisp.com> writes
>Dick,
>
>Michael K. is right on course. The purpose of heat treating metal
>to obtain spring like properties is to modify the strength
<snip>
>Gary Click
>
>Michael wrote:
>>
>>
>> Procedures for hardening, tempering, quenching, and annealing metals can
>> be found in any edition of the American Machinist's Handbook, editions
>> of which have been in print since 1908 and are readily available. The
<snip>
>> Michael K.
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Cal303
the spring red hot then quench it in water or oil we then put it in a small
tin with some tallow or whale oil (i am shaw your brine is the same process)we
then play the flame on the tin untill it reaches its flash point and catches
fire we just keep it alight untill the oil tallow has burnt away then leave it
to cool naturally
also are you aware of blueing salts?.
Steve Rayner
follows:
Heat red hot, and quench in brine or water. Place objects in a basket (
Metal ) or hang with wires in a pot of pure olive oil. Heat until the oil
boils ( 600 F at sea level ). Hold at boiling for several minutes, remove
parts, and quench.
If you do wheel cutting as I did in the trade, save your brass " Filings
". Harden as above, then bury the parts in a metal container of the
filings. Place a piece of the same metal on top. heat over an alcohol
lamp, or propane torch until the piece on top turns blue, and dunk in cold
water.
Flat parts can be hardened, cleaned up, and tempered by heating on a piece
of sheet metal. When blue tip into water.
Cal303 (cal...@aol.com) wrote:
: hi i am a gunsmith we have to make leaf springs also our methord is to heat
--
I'm a Canadian eh! Steve.
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