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I Forge Iron

Should I keep going?


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Good day. I welded this billet up the other day, all seemed well, and today i was in the process of drawing it out to cut, fold, weld, etc. when it developed a nasty delamination. It appears to go all the way through, right in the center of the billet, of course! The billet is currently 8-1/2" long, and the delamination *appears* to be about 3 inches. My question; if I attempt to cut fold and weld the two halves (which will both have a partial delamination) what are the odds that it will close itself back up on both pieces? Is it not worth my time to continue with? Should I just take the solid steel on the edges and continue with those? Probably won't be enough for a knife like I had planned, but still usable. In fact, this makes me question the integrity of the whole billet. The edges *seem* good. Sorry for the bad pics. All I have is my phone. 

If it makes a difference, the billet is alternating layers of 5160 (3) and 1075 (2), five layers in total. 

Thanks in advance. 

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I have *read* 5160 does not like to weld to itself, and the recommendation is to set your stack so the 5160 is not the outside layers. Based on your counts my guess is you have 5160-1075-5160-1075-5160, so that could be an issue. This is purely theoretical coming from me as I have read about but not yet attempted. Hopefully someone with some actual experience on the topic can jump in.

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If the original weld was done in a neutral fire it may yet stick. You can flux it and try to reset the weld but if there is already scale in there it's probably not going to weld. The only thing I've ever welded 5160 to is mild for axe heads but I have been told 5160 doesn't like to stick to itself. If you do get the billet to weld up and you still want to fold it you could try inserting another layer of 1075 into the fold. When a billet opens up in the center it can mean it wasn't up to weld temp all the way through the billet. It can be tricky with solid fuel to bring a billet up to heat without burning the outer layers but five layers will be easier than a great big stack.

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I do have some more 1075 laying around I believe. I may throw one in, assuming all goes well. I'm not positive on if there is scale in there. I stopped forging on it the second I noticed the delamination for that very reason.

I really did beleive I had it up to temperature the entire time I was welding it. Initially ground down the sides and it was spotless as well. Nothing is a guarantee I guess. 

Any idea why 5160 doesn't like to weld to itself? I've never heard this. I'm not denying it, I'm just curious. 

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Did some research on it. Seems like everybody, on various sites, is indeed saying it's hard to weld to itself, but nobody has a clear reason why. Stainless has way more chromium, and has been welded in billets, and likely to itself. Not entirely sure though, I'm no expert metallurgist. I also read that welding some 10 series steels (like i did) to 5160 can cause problems due to differing contraction rates, though it depends on the alloy. Cpuldnt find much on 5160 and 1075 though. Definitely learned a whole lot from this! Thanks for the responses everyone. I'll give it a go at fixing the billet tomorrow. Maybe it will work, or maybe I'll have a nice paperweight and one more lesson learned!

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Chrome oxide is pretty inert and has a high melting temperature. Chrome also forms an oxide layer very VERY quickly so even taking it right of the sander, fluxing and trying to weld it may not work very often.

The fluxes used for chrome alloys contain flourine compounds are VERY aggressive and pretty darned toxic. I believe flourspar is a common old school one as is Sal ammoniac. Do NOT breath the fumes, get them in your eyes or get much on bare skin. It's bad scoobies.

Frosty The Lucky.

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Frosty

Thanks for the info. So, i am curious. If the chrome oxide is to blame, why is it that 5160 can be welded to different alloys? If the chrome oxide still forms, it should make it difficult to weld period, right? And what about stainless for that matter? People have welded stainless in billets before, and that has way more chromium in it. I'm not trying to deny or challenge any of your knowledge, these are genuine questions. And I think I will just find better alloys to work with, rather than use dangerous fluxes like those. 

JHCC

I read most of that discussion, actually. Steve also mentions the flourine flux that Frosty was talking about in that one. He must have some REALLY good ventilation to be confident in working with that stuff.  

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Good question. 5160 rusts meaning the chrome content isn't high enough to prevent oxygen from reacting with the iron in the alloy. There  just isn't enough chrome. Weld two pieces together and perhaps the chrome oxides in the surface layers is high enough between the two to inhibit welding. It doesn't prevent forge welding it just makes it harder. I was welding spring steel to itself before I knew any better. :rolleyes:

I don't know the chemistry involved but I'll happily speculate. (educated guess for the vocabulary challenged out there) Diffusion welding is a process where molecules of different metallic objects are brought in close enough contact they begin swapping electrons and when a large enough imbalance occurs nuclei exchange and the two become one. Getting the steel or other metals hot causes the molecules to move farther and faster, "Brownian movement," the two objects get slammed against each other really violently on a molecular scale so electrons then nuclei are exchanged more easily and quickly. Give the billet a rap with a hammer and viola!

Fluxes do a couple things to make diffusion welding easier, they put an air barrier on the joint surfaces that is easily forced out of the joint. As it's forced out of the joint (squirts all over the place in a glorious yellow glowing shower!) it carries crud, bits of scale, clinker dandruf, whatever might have been caught in the joint.

Now for the speculations. What happens to molecules of chrome oxide that is suspended in a matrix of molten or nearly molten steel and bathed in flux? If it's a flourine containing flux it's deoxidized and returned to "clean" chrome which just alloys with in the joint. Easy peasy, yes? Do chrome oxide molecules get forced into the alloy of a joint if there aren't enough to form a solid barrier? Maybe? Maybe if there aren't very many they can be deoxidized enough to not interfere?

Lots of us weld chrome moly steel, 4130, 4140, etc. without using special fluxes but it's not a snap. 

Welding stainless is a different matter. It's stainless BECAUSE it has so much chrome that the surface oxides encapsulate the alloy in a relatively inert layer. Layman's description of what's going on. ;)

You can use aggressive flourine containing flux on low alloy steels and it works darned well but you're running a health risk and need to take appropriate measures. I don't know of anybody welding stainless without using aggressive fluxes but I don't know everybody's secrets.

Frosty The Lucky.

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Frosty

That's interesting. Thank you for the detailed post. It would seem then that there is just enough chromium in there to cause an issue, but not enough to solve said problem. I suppose, given my lack of experience, I should definitely do more research on Damascus, find easier to weld alloys, and stop just going for it near-blindly. Again, thanks for taking your time to reply. It is appreciated. 

Jackdawg

I tried to weld the delam back together, but it didn't take, even after several attempts. I suspect there is scale in there. I may try to open it back up, clean it, and fix it, but at the moment, my confidence in my welding abilities is yet again shaken. The fact that all seemed well (even after ground flush) until I began drawing it out is proof that my welds were weak, at least in that particular spot. 

 

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I no longer have the literature available to check this out but I could follow Frosty's exampe and speculate: Normally we use Boron based fluxes. The borax/poric acid forms relatively fluid compounds with many metal oxides (including Iron) that are fluid enogh to be squeezed out of the joints. Maybe chromium oxides do not react with the borax or (more likely I think) the result is not fluid enough to be squeezed out of the joint.

 

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