Forging welded steel

I got a question about forging pattern welded steel. I've noticed that after doing the initial weld and draw at some point during the squaring up
of the material I'll hit the layer edge just right and the layers will split open. Last time I was working a blade of layered steel I was able to hammer it back together and seemed to weld up just fine (not counting the one really bad weld that killed the blade). I'm working another billet and the same thing happened. I was hammering the edge and everything was fine and then all the sudden it mushes open. Not deeply but just along the edge of the billet. Now Jim Hrisoulas in his book mentions proper forging tempertures for pattern welded steel and I'm thinking that what I'm doing is getting it too hot to work? I took a K type thermocouple to to forge this last time to check tempertures after I was done forging and discovered that my forging temperture was at well over 2000F (which is where My reader quits reading....) I didn't realize I'd been working that hot. Will working at lower tempertures stop the delamination? Just to be clear I'm talking high carbon materials, not low.
GA
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Greyangel wrote:

If you had the Steel too hot it would blister and burn, which is a whole different problem (and will ruin work even faster than a bad weld). Forging it cooler might actually make the problem worse (or at least make it harder to weld). I suspect you aren't getting enough flux into the weld area or are not using enough force to get a good weld or maybe even have bad technique (though I doubt this if you are doing Pattern Welded blades). Ken
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This is how I was told to check my welds. If they delaminate when struck on the sides then the weld wasnt a good one. I just reflux and reweld which seems to work. I use borax and boric acid as a flux for these incidents as the boric acid cleans the steel. I do not however use the pattern welded steel for blades, but purely decorative so inclusions are no as critical, but often add to the texture of the piece. Doug

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Greyangel wrote:

Sounds like a cold shut. WD-40 can yellow, that's the color. Back in the fire at orange, no such thing as too much flux. When I first started making cable, I'd take the billet and clamp it in the vise and try to 'unwind it' with a big wrench. If it twisted 90 degrees without coming apart, it was a good one, so I'd warm it back up and straighten it out. Then I got the powerhammer and I stopped having delamination problems. By hand, I'd usually get about a dozen good strokes before it cooled off, with the LG I get about three times as many strokes before the iron is too cool. Patience, more fire, more flux. I found that if you crown the face to be welded, you get better grab in the center. Doesn't take much, just a little ramping from the center to the edge. This helps the flux squeeze out as the pieces bond. Don't force it, use a bigger hammer.
Charly
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Not saying all of the responces don't have valid points but what I'm talking about happens after the welding has been done. I've already hammered it on edge some and the welds appear to be stuck nicely - but then later when shaping the bar, the edges will suddenly spread open some if hit just right. Is that necessarily a bad weld or am I introducing conditions that will pop open a good weld? This last billet was hammered from corner to corner to sqare it up after the initial welding had made the stack kind of tilt to the side and it showed no weakness between the layers at that time.
GA
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Greyangel wrote:

Bad weld. A good forge weld forms a homogeneous unit with no lines of demarcation.
--
Tom Stovall, CJF
Farrier & Blacksmith
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Greyangel wrote:

Hey, I've had them too. When I looked closely at the failure, the edges of the billet had fused but not the center, and there was a film of trapped flux in the pocket. Big billets I crown before I lay them up... now. Just a few thousandths is all it takes, a quick pass with the grinder.
Charly
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I have been experimenting with Mokume Gane and have found that the edges often have to be trimmed with a band saw as oxidization prevents a perfect difussion. I believe your problem to be similar.
Recently I saw a billet making demo at the fall NWBA conference. The demonstrator made his billets with a piece of ERW tubing. He sealed one end of the tube then packed it with the steels he wished to use. He then sprayed a little WD40 in to burn up any oxygen. He then closed, but did not completely seal, the opposite end. The packed tube was let to soak until the black outlines of the metal could be seen through the tube walls. At this point the forge was turned up to welding heat and welded together.
He ground the outside off but I am sure that stage could be eliminated if you were to chisel or mill your pattern into the billet.
The main reason I wanted to try this method is ... no forge eating flux.At least he did not us any and his welds looked perfect.
brad
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Brad wrote:

Well, that makes sense. Once the WD 40 flashes off, there's very little oxygen left in the vessel, and the likelyhood of significant amounts of O2 getting back in during the heat are low. This would be a good technique for 'picture' damascus. Once you got the layup, you slice it like a salami and make tiles to weld to a substrate. Picture damascus was all the rage in the Knife mags about a decade ago, including several good how-to spreads. Looked like a LOT of work with a high failure rate. Definitely something for one-offs, not practical for a production run.
Charly
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