I need to harden some cuts of steel. This is the grade known as 'guage
plate' which AIUI is a low-medium carbon content steel. All I know is
that it has to be heated to a certain fairly high temperature, then
quenched in oil, water or watever. Then it has to be re-heated to a
somewhat lower temperature and allowed to cool back *slowly* again to
room temperature. This second stage is called 'tempering' I believe.
But that's as much as I know. Does anyone know what the correct
temperatures should be for each stage and the best mediums for the
quenching part and the slow cooling part?
Any info would leave me slightly less ignorant than I am at present!
"I expect history will be kind to me, since I intend to write it."
Found on google (google is your friend!)
What you have there is probably O1 tool steel, which is actually a
relatively high carbon steel (0.85% to 1%), but it's important to be sure.
Water quenching is dicy, oil works better on the higher carbon alloy steels,
although this will depend on the tool size.
so far you've more or less got yout heat treating tempering terms correct
...... heat to around 800C and hold it there for a while, how long depends
on the size, and then quench in hand warm oil, vegetable oil works fine for
this. Tempering should be done immediately and temperatures depend on what
qualities you want on the steel, hardness or toughness. What exactly is the
steel for and what size are the pieces?
here's a bit of reference for you;
Gosh ... i answered your question Paul, you could at least answer mine :-P
the size and use will have a reasonably significant influence on how you
treat the steel
I'm sorry, Simon. I did answer your post last night but for some reason it
I've got two principal sizes and shapes to harden. The guage plate is 8mm
thick and is in small chunks of a few square inches each. Could these be done
with a blow lamp and if so, how will I tell when it gets to 800 degrees?
The other part is a shaft of 28mm diameter and weighs about 3 kilos. It's
got a long tapered point at one end. I do have access to a forge if necesary
for this piece. It's a slightly different carbon contenct to the plate but
not by enough to worry about. Any ideas? (thanks for the references youa and
the other chap provided, btw).
That's ok ... I wasn't being serious :-)
how much is a few inches? and how long is the shaft? it sounds to me like
you are making some kind of axe for a robot wars machine now that i put your
2 posts together :-D
I wouldn't say that you are looking for fine tolerances like if you were
making a knife blade, blade makers can be very anal about their HT methods
;-) and you could end up with loads of normalising and cycling and you don't
really need that.
you'll never get your "teeth" hot enough with a blow lamp unless you build a
forge around it out of fire brick to insulate it, or maybe a large diameter
metal tube that you can insulate with refractory wool (available from
pottery suppliers, etc.) place your "teeth" inside, block the ends up with
more wool and leave an aperture you can fire the torch inside, this should
retain enough heat. A good plumber's torch should get you by as long as you
keep the cavity as small as possible. From then on, keep checking on the
"teeth" and look for the orange glow in the steel, when it gets close, take
them out (with tongs) and test them with a magnet ( a good idea is not to be
holding the magnet at this point, but to have it stuck to a metal object)
......when the right temperature is reached, your "teeth" will lose their
magnetic qualities, at this point, just check that you have a uniform colour
(best to do this somewhere with reasonably low light) and then plunge it in
to warm oil, hold it there with the tongs untill all the fuss has died down
and then quickly get it to your preheated to 200C tempering oven ( a kitchen
oven will do at a push) and leave it there for a couple of hours, this will
work fine for the shaft too as long as you get a uniform heat prior to
quenching. your shaft will require further tempering at a hotter heat though
which you could do with your plumbers torch, but do this after the initial
oven tempering, heat until blue and leave to cool...... there's a lot more I
could go into ... but the subject is huge and i am still learning (aren't we
The other option is to find someone to do it for you and remove the hit and
miss factor. there are plenty of heat treating services out there or you
could even find a college that has a smitthing course and see if a student
fancies taking it on (cheap option)
So what are you building? ... go on ..... and if I am right ... you need to
look in to certain steel restrictions that they have on robot wars ;-)
you've got mail ... or at least if I got the remove this bit right and
removed the right bit ;-)
nice colour reference chart
it's for mild steel but the colours aren't too far off
On Sat, 11 Oct 2003 19:22:13 +0100, alex_sh@w wrote:
Look for the Curie point (this works for all (sic) steels, some of
which want different temperatures). Heat it up until a magnet stops
sticking to it, then you're there.
The "O" in "O-1" stands for oil-hardening. An "A" would be an
air-hardening steel. Other letters are less obvious.
Good enough for jazz
Die Gotterspammerung - Junkmail of the Gods
Sorry, I should have also mentioned, the shaft needs to be hardened in such
a way as that it won't bend; the plates need to have the quality of 'teeth'
so they will penetrate other softer metals without bluntning or gouging.
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