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Posted by Curt Welch on April 9, 2010, 7:32 pm
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> The first thing is to know what the hammer is made of.
> It could be water hardening or oil hardening steel.
In my case, I had no clue what the steel was.
But even if it's oil hardening, isn't it possible you might have to harden
in water to get it to cool fast enough?
> We have made lots and lots of hammers from 1045. I know a guy who has
> made a thousand or so from 1144 or is it 1141 (Stressproof).
> But, others may use something like 4140.
> I think it is unlikely that the Chinese are gonna use anything but cheap
> simple carbon steel for their hammers.
> That makes it a water hardening steel in my mind.
>
> Do you know about TTT curves as they relate to how little time you have
> to get full hardnes with plain carbon steels?
No, I've never heard of that. But my understanding is that the rate of
cooling determines the hardness, and that some allows are water hardening
or oil hardening based on how fast they must be cooled. But yet, it seems
to me, a large chunk of steel is going to cool far slower (even on the
surface) than a small piece simply because it's got more internal thermal
energy to dissipate, and all that energy has to travel through the surface
to the quenching liquid.
I guess, now that I think about it, how fast the temp of the surface drops
will be a trade off between the speed at which the heat is conducted
through the metal, vs the speed it is conducted through the steel-quench
liquid barrier. So maybe the speed the surface temp drops is more
controlled by the type of quench liquid than the size of the steel. The
interior will by nature always have to drop slower and end up being softer
as far as I can see however.
> Many people harden hammers with a rosebud torch these days. Oxy-cetylene
> would be better than oxy-propane, because you can get things up to heat
> faster when you need it.
> After forging and/or normalizing, you heat a half inch of the end or
> so to non magnetic, then quench in cool, not cold water. The eye area
> never got hard eonugh to harden at all, so it stays soft.
hot enough?
> Assuming this is a hammer with a pein, do the same thing to the other
> end.
Ok, so the trick is to find a heat source where you can get the end past
non-magnetic without getting the rest there. It does seem tricky however
to heat the second side up, without getting the first hot enough to temper
it. I guess you just have to cool the first one from time to time as you
are heating the second side.
> Now the ends should be pretty much file hard.
> Now, carefully heat one end of the eye area (keeping some water around
> for control of the other end), and watch the colors run toward that end.
> Try to do one end at time, looking for, in my opinion, a dark straw.
> Take you time or the colors may run too fast.
> Quench the end half inch. Keep swirling the end around for a long time
> so the latent heat from the eye area can't creep back in to the end and
> advance the colors.
Sounds simple enough. I'll try that on the next one. I used oil for
safety (that is would rather under-harden than over harden and crack), but
I bet you are right that the cheap Chinese hammers I was playing with were
likely just carbon steel and probably needed to be water hardened. I've
got enough cheap ball peen I want to turn into something else. I'll try
water on that and see what happens.
> Pete Stanaitis
>
> Curt Welch wrote:
> > Since we were talking about how to heat threat an anvil, it reminded me
> > that I also would like to hear ideas about how people heat treat
> > hammers. I've modified a couple of hammers and had to heat treat them,
> > but it was just random guessing on my part how to best do it. I'm
> > talking 2 to 3 lb blacksmith hammers of different types.
> >
> > The last one as a 2 lb harbor freight sledge that I turned into a
> > rounding hammer. I simply heated the whole thing past non-magnetic and
> > quenched it in vegetable oil. I don't believe I made any attempt to
> > temper it after quench. Can't really remember. It doesn't seem to be as
> > hard as it should be, It marks fairly easy if I hit anything other
> > than hot steel.
> >
> > I've heard one person once talk about running a stream of water down on
> > the face with the idea of making the center of the face harder than the
> > edges. I don't know how much water he was thinking, nor do I understand
> > how you would heat treat the other end if you tried that technique.
> >
> > Anyone have any experience or suggestions on how to heat treat a
> > hammer?
> >
--
Curt Welch http://CurtWelch.Com/
curt@kcwc.com http://NewsReader.Com/
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