Cold Steel Forging

[wulfgar]

Todays question! I bet you're all looking forward to what it is Ah but if you have read the title I'm quite sure you know. What I am asking today is what are the do's and don'ts of pounding steel at too cold a temperature? First I better start with my problem. I have been trying to draw out an old leaf spring from a truck to make a sword. The way i have been working it (and please correct me if I am going about it the wrong way) is laying it width up and pounding it into a more square shape instead of flat and rectangular (taking it from 2.5" wide to 1" wide). My forge doesn't seem to put out an excessive amount of heat so I've been working the metal at a bright red almost orange color. I put it back in the fire at a dull red. The problem that arose is the metal seperated. Am I pounding it too cold? Can steel be pounded cold and am I just using too much force? Any other criticism or advice is more then appreciated
Thanks in advance to all who respond.

[Don A]

There are a lot of problems with trying to make judgments based on the color of steel without actually seeing what you are talking about, but yeah, if it is truly "dull red" in a dark / dimly lit shop, you are hitting it too cold.

[dablacksmith]

probably to cold but also are you useing a used leaf spring? they can sometimes have flaws in them ... i do use old leaf springs but if its gona be a fancy ( time consumeing) piece i go with new steel.. i had nice falchon i made that had a hidden flaw in the steel had it completely built and finished was cutting some kindling with it and 'ping' broke at abput 3 inches from crossgaurd...you might want to just bite the bullet and buy some steel closer to the size you plan on working with ... forgeing leaf spring down from 2 in to 1 in is hard work without power hammer... or heat the leaf spring flaten it and let it cool down slowly to aneal it then cut it with saw ... good luck

[JohnW]

wulfgar
Let me suspend all judgement about sword making technique and just talk about forging leaf spring. I don't know anything about sword making anyway.

Bright red almost orange doesn't sound terrible. I would preferr almost yellow. Others have advised that almost orange is better for the steel in that it burns out less carbon. The piece will get hotter after a few heats. It will heat up faster and it will just get hotter.

I don't understand what you mean that the steel separated. Did it split lengthwise into layers?

What you're doing is a tremendous amount of work. You can't expect to draw out a whole leaf spring in a single day, at least not with a 2 pound hammer.

Now, if you want to draw out the leaf spring, that is change it from 3" x 1/4" to 1.5" x 1/4" or some such thing your beginning technique is right, lay the spring edge-wise on the anvil and hammer it. This will begin to flatten the top edge where you strike it and the bottom edge where it contacts the anvil, and probably begin to wrinkle the steel in the middle. When I say it flattens the top edge, I mean it begins to make a T. While you still have a little heat left, lay the beaten area flat on the anvil, and beat the lip down that formed on the edges and take out the wrinkle. Reheat to finish this if you have to. Keep the edges well rounded.

Start with just the first 2" to 4" inches, that is just put the end of the spring across the anvil.

All this pounding puts a lot of stress on the piece. After you work it for a couple hours, you should let it rest in the coals (no blower) for a couple hours to relieve the stress. when you're done for the day, just leave the piece burried in the coals.

Are you burning charcoal? You probably don't want to burry the piece in the coals if you're burning coal.

Now you said something about make the steel square. Are you trying increase the thickness? That would be upsetting not drawing.

[ThomasPowers]

If you are forging above the dislocation climb temperature you can't put any stresses into the material, I know of no reason to "rest" the material if it's been worked at the proper temperatures.

Blademakers often do a normalization or anneal before they start the stock removal just to catch any places that may not have been up to the correct temp; but this is only done once before you start the cold work. After most of the cold work you generally normalize a couple of times but this is more to refine the grain though it will help clean up any grinding stresses before the hardening steps

[metalmangeler]

Hi Wulfgar
Forging a section of flat bar 1/4X2 on edge should be pretty rough as the edges want to move more than the middle you are likely ending up with a small I beam. If you can keep the width to thickness rato 1:3 things work much better, then as you aproach the end of the project make it thinner. Perhaps starting with a heavy coil spring or spliting the leaf spring would work better. If I were trying to get 2 inchs of leaf spring down to 1 inch with only hand tools I would get someone to strike and use a hot set with an offset handle. Be sure to put a cutting plate on your anvil so you don't wreck it or your tool. Also be sure to have fun.

[Alan B]

A lot of leaf springs carry hair line, spider web like cracks. I have noticed these in the springs I work. If the steel is too cold these will surely open up on you.Tom Stovall once said, the only thing that will send a smith to h#ll is striking cold steel. This has 2 meanings. #1 it's harder to work requiring more force and effort and #2 it will take its toll on your tools and the steel itself. If I'm not worried about carbon migration or using austenite forging I work the steel as hot as it will allow. Easier on me, my tools and saves some time.

[steveh]

there are 2 things that will send a smith to that PLACE,hitting cold steel and not charging enough!

[Glenn]

LB0007 Seeing colors

[evojcak]

IMHO your not reducing cross section enough - get as hot as you can and hit as hard as you can only once and then re-heat - small hammer blows do not allow enough time for the steel to relax (stress relieve) leading to an "allegator" in extreme cases.

BTW - You can check temperature with magnet - Springs are usually 6150 steel and start to go nonmagnetic ~1360ºF fully nonmagnetic 1450ºF .

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