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I Forge Iron

tips on forge welding


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I just had a class with Gordon Williams at the NWBA Spring conference. He showed us a flux called Black Magic that is great for propane forges because it does not harm the refractory in any way! Nice stuff. I tried it at the conference but haven't sent off to buy any yet.

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I decided to have a go at forge welding this weekend. It's one of those things that loom on the horizon, you know there'll come a time to tackle it. well, today was it for me. I figured I'd do like normal and tackle a big job to start with, (built a stone BBQ once and reckoned that qualified me to build a stone house, which I did :huh:) so I decided to make a tomahawk with a spring steel blade welded in.

I'd seen a Youtube doco of someone doing just that and thought "Why not".

So, I took an old rail spike, the really old round ones
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and I forged the head a bit before splitting it with a hot-chisel. I then forged an edge onto a piece of leaf spring and cut a bit off it.

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I held the cut off bit in the vice and using a cold chisel, cut small curls into the edge, so it would 'hook' into the rail spike. I heated the spike to bright orange, scrubbed off the scale and sprinkled with Borax, before putting back into the fire and brought it up to a near-white-yellow. I dropped it into my home-made swage block and tapped in the spring steel. The spring steel was cold. I tapped the sides of the spike closed along the spring steel and then re-heated everything, de-scaled, Boraxed, and brought it up to "really hot" again and started blending them together. After about four repeates, the magic happened and it was one piece of metal! I kept peering closely to try and find the join line....and there wasn't one!! (Remember Tom Hanks in 'Castaway' when he finally made fire? Well it wasn't quite like that , but I felt pretty good all the same :D)
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I then went on to finish the 'hawk, and that's when things went pear shaped. I squared the shank of the spike and used a hot chisel to slit it for drifting. I noted a 'crack' along the side when I slit it. I thought maybe not enough heat, though it was pretty bright when I used the chisel and it just got worst as I went. I tried 'cooler' temps and back up near melting point, but to no avail. The XXXX spike just kept 'tearing' for want of a better word. I'm sure someone here can enlighten me as to what went on with this spike. I thought I'd perhaps got a dud, so grabbed another of the round spikes, heated it and started to shape it and it too fell to bits. Definate head scratcher. I welded the head, but could do bugger-all with the shaft.
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So, disappointed that my first welded 'hawk didn't turn out, but at the same time, pretty XXXX chuffed that I've forge welded.....

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While it may still be the heat that you were working at, that looks to me more like wrought iron delamination, or linear splitting at the grain boundaries of a rolled steel. A true tear would just be jagged and head towards the side.

That is the problem with dealing with mystery metals, every piece is a challenge. If it was a leaded or sulpherized free machining steel, it will never forge without cracking.

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Ok, thanks for the info.
So I gather if I'm using wrought iron then we're talking much higher temperatures than usual? I haven't had anything to do with wrought prior, but if that had been a square RR spike, it would have shaped up fine at the temps I was trying out.
(and the head didn't crack-up, but apart from the splitting, I was operating at welding heat, so I guess I answed my own question.... :)

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The wrought iron produced from raw ores in a coke fed blast furnace of our grandfather's day is a whole 'nuther animal than today's computerized scrap fed electric furnace continuous cast mild steel. That is one of the reasons going by the directions laid out in books from before about 1950 do not produce the same results.

It's like trying to make flakey biscuits out of corn meal: not going to happen. The ingredients shape the process, and help determine the outcome.

Salmon red would be a medium forging heat for modern low carbon steels, but is too cold for wrought and will cause delamination. Wrought *has* to be forged at what would be considered a welding heat to burning for most steels: lemon yellow to white. It *is* a welding heat, because you are constantly welding the self fluxing bundle of fibers we call wrought iron back in on itself.

If you punch or drill wrought, you weaken it by cutting the fibers. You want to slit and drift "frog eyes" along and not across the grain in the metal, or wrap it back on itself and weld it.
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MO, John, thanks for the info. I had a go at fixing it, but no joy. I had it up to 'Sparkle' heat by the end and still couldn't get that sucker to stick back together. I'll hang it on a nail for future investigation, and put the rest of the wrought spikes to one side also. When I become more proficient at forge welding with less taxing materials, I'll come back and have another go.
John, thats a good progression photo of the wrapped tomahawk, thanks for posting it.

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I agree with Frank. Also sounds like you are working too cold .."when its yellow, its mellow, when red its dead." Dont be afraid to get it hot. Forge at a yellow, finishing heat is red, and forge weld from a good yellow to light sparking,,and finally, hit the durned thing.

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I describe the weld setting blows as "firm rather than sharp" You want to push the metal together not bounce one piece off the other. And once set heavy hammering is good for a weld (as long as it's still hot)---why you can weld and draw out in one heat on a powerhammer

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I've never welded chain, but when a weld doesn't take I only blame two things, heat or scale. How fast can you pick up your wire brush and then hammer?
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I'd imagine welding small bits might be easier on a large hot piece of metal too.. but that's a dance I'm not personally confident it pulling off.

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Matt you still have'nt told us where you are, you could be just down the road from me, or you could be in the top end of WA somewhere. Australia just doesnt narrow it down enough, we can fit more than a couple of whole european countries into some of our states. There are a lot of us here, sure one can help you.

Phil

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