HT advice for a hammer head

[MattBower]

I have a commercially bought cross pein hammer (Czech type from Kayne & Son) that I just recently started using. The face is a tad soft for my liking. (And yeah, I realize it wouldn't be an issue if my hammer control were better.) I wasn't going to worry about re-HT'ing immediately, but last weekend as I was making a forge weld the head flew right off the handle! I'm kind of underwhelmed about that, but, err, well....as long as the handle's off, I suppose there's no time like the present.

I've never heat treated a hammer head before. I've read about it, but I've never done it. So if any of you folks with experience in this area would like to offer any tips, I'd be happy to hear them. Water, brine or oil for quench medium, best process to use to get good hardness while avoiding cracks around the eye, that sort of thing....(And yes, I realize the fact that this is mystery steel complicates things some.)

[rthibeau]

heat to nonmagnetic, quench in oil, use torch to heat in and around the eye until the colors start to run, fully quench in oil again just as the color purple creeps to the edges of the face and peen. If that doesn't come out hard enough, do it all again but quench in water.

[MattBower]

So go ahead and quench the eye?

For what it's worth, I called Blacksmith Depot and discovered that the steel used in these hammers is 4140.

Edited June 4, 2009 by MattBower

[medieval]

I have HT'd many hammers. I got a lot of practice when I made special repousse' hammers ALA Nahum Hersom. What I have been doing, is heat treating the face and peen, rather than the whole thing, because they have a tendency to crack across the eye. Also, the mass of a 2-3 pound hammer doesn't allow the head to cool quick enough (except at the eye). Put the head in the forge, bring it up to critical temp (just pass non-magnetic), take it out of the forge and set it on a plate and allow to cool. This normalizes it. Then, using an oxy-fuel torch (rosebud tip, if you've got it) heat the face to a dull orange, be patient, when color is about 1/2" deep, quench in water. The idea is to bring the temperature down from critical to 400 degrees (or less) AS QUICKLY AS POSSIBLE, so don't dip in water then take it out. Put it in the water and swish it around. Repeat this proceedure on the peen end. Clean up and put it in the oven at about 500 degrees. Let the hammer head soak for 2-3 hours. Chisels can be taken out after 1-1 1/2 hours. This has been verry, very god to me. :D

[rthibeau]

if the steel is 4140, use oil to quench. The heat around the eye will migrate to the face and pein for tempering, leaving the eye essentially untempered and softer. I've never had one crack around the eye.

[Charlotte]

I have HT'd many hammers. I got a lot of practice when I made special repousse' hammers ALA Nahum Hersom. What I have been doing, is heat treating the face and peen, rather than the whole thing, because they have a tendency to crack across the eye. Also, the mass of a 2-3 pound hammer doesn't allow the head to cool quick enough (except at the eye). Put the head in the forge, bring it up to critical temp (just pass non-magnetic), take it out of the forge and set it on a plate and allow to cool. This normalizes it. Then, using an oxy-fuel torch (rosebud tip, if you've got it) heat the face to a dull orange, be patient, when color is about 1/2" deep, quench in water. The idea is to bring the temperature down from critical to 400 degrees (or less) AS QUICKLY AS POSSIBLE, so don't dip in water then take it out. Put it in the water and swish it around. Repeat this proceedure on the peen end. Clean up and put it in the oven at about 500 degrees. Let the hammer head soak for 2-3 hours. Chisels can be taken out after 1-1 1/2 hours. This has been verry, very god to me.

That is a well thought out procedure. The cracking across the eye problem can be reduced by inserting a length of undersized hot stock in the eye and quenching only the face or the peen. Some authorities recommend drawing the temper with hot stock inserted in the eye.

[MattBower]

Medieval, what sort of steel were you using for the hammers you're referring to? I've read conflicting reports about the right quenching medium for reasonably heavy sections of 4140, both here and elsewhere. Your differential heating and hardening approach like a smart idea in any event; there's less residual heat to have to deal with that way.

[tommerr]

Estwing is here. They use 1045 steel for their hammers. One of our metalurgists called one of their's and somewhere I have their heat treating process. I don't trust Chinese products. Even their food kills people and dogs.

[bigfootnampa]

My process seems simpler to me but has worked very well. I have been reforging hammers to get improved shapes and, as I have had some problems with keeping the heads tight on some of my old hammers, I now redrift the eyes to make sure of a nice waisted taper there and also to stretch the eyes so that they take a larger handle for strength since I tend to put them to heavy use.

After the final shaping and drifting is done I reheat one more time and quench in water (the entire head... and swishing very swiftly) to harden. Then I use a flap disc to grind away the surface scale (I also use this opportunity to dress the hammers edges and faces to final shape and smoothness) so that I can see the colors for tempering. I then set the hammer back on top of the forge fire (mine is coal) and continue forging for a couple of hours or more. I turn the hammer often as it slow bakes atop the fire and let the heat flow through the eye often watching for the colors... when I get mostly dark blues (maybe just a bit of purples) I requench the hammer. This seems to give me a good hard face and peen with a (possibly) slightly softer eye and anyway very nice performance. Hammers treated thusly give me much better service than ones that I have bought, whether new or old. They are hard enough to keep their shape and have durable surfaces but do not chip or crack even when used to pound like crazy. They are harder than my anvil faces but mine are dressed with no sharp corners and I have developed very accurate hammer control... a ding is rare and tiny.