Forge welding question

[Buzzkill]

I decided to try forge welding a billet (1095 and 15N20) for a blade without using flux.  I have some kerosene, so I chose to soak the stack in kerosene  after arc welding the stack together and also arc welding a short bar on the stack to grab with tongs.  I'm using a propane forge, btw.

The initial weld went fine.  I had a solid billet with no apparent delaminations or dark lines as it cooled.   After drawing it out, I hot cut the billet in the middle (leaving only a thin layer uncut), brought it back up near forge welding temperature, used my butcher brush vigorously on the mating surfaces, and folded it back on itself. I brought it up to welding heat and attempted to set the weld, but no joy.   Since dunking a glowing chunk of steel in a container of kerosene seemed like a really bad idea, I grabbed the flux and proceeded to weld the billet with satisfactory results.

Is there a reasonably good way to fold and weld a billet without flux (or anything else likely to produce inclusions) and without letting it cool back down to use something like kerosene?   Flux inclusions haven't been a huge problem for me, but it is always annoying to hit one on the finish grind after all that work has been done.  I'd rather eliminate the possibility if I can.

[rhitee93]

I pretty much stopped using flux a couple of years ago.  I'll still crawl back to it for something with a complex geometry where I can't get it welded before I have oxidation issues, but none of my pattern welded billets get fluxed anymore.

The kerosene dunk in not necessary if your forge environment is correct.  It is not a flux, and the only benefit it brings is using up any oxygen that might have been trapped inside your stack before it has time to oxidize your steel.

What you are fighting after your first weld was the forge scale that formed on the outside of your billet.  In my opinion, the only way to get that to weld again without flux is to allow it to cool, and grind the mating surfaces clean.

 

[Buzzkill]

I don't foresee going back to flux for pattern welded billets at this point.   I haven't yet tried one without flux or kerosene, but I have gotten good results on the last couple using kerosene.   I really didn't want to let the billet cool down to increase the layer count for fuel and time purposes.  However, I'm now drawing the billets out further and then instead of a simple fold, I cut about 4 inch lengths, grind the mating surfaces, and stack the billet back up 4 or 5 layers deep.  That's been working out well.  On the most recent billet I went up to about 50 layers and then flattened the billet perpendicular to the layers without getting any delaminations, so I'm happy with that.

I'll have to try a billet with nothing to aid forge welding.  Kerosene does tend to leave a lingering aroma on my clothes and in the building.

[rhitee93]

 I hear you about fuel usage.  lately I've been stacking up my welding projects until I have enough work to justify getting the forge up to temp.  Still kind of a bummer to let things cool down.

[Bob Brandl]

The kerosene is acting as a flux. When it burns off the residue that's left behind coats the surfaces of the steel, preventing oxides from forming and keeping the steel from welding. Same as borax. Technically, you can avoid using anything at all with a proper gorge environment, as stated. I would just draw out the billet as much as you can, let it cool, grind the surfaces clean, and re-stack and weld again. Less chance for failure and not that much more work.

[JHCC]

We had a discussion a few years ago about using WD-40 in pattern welding. I can't recall who was advocating for it initially, but their rationale was that if you grind your layers clean and immediately give them a spritz, it keeps the freshly ground steel from rusting. Later, when the billet goes into the forge, the hydrocarbons will ignite and scavenge any oxygen out of the weld. This latter is basically the same rationale as using kerosene.

It's worth noting, though, that WD-40 and kerosene do NOT act "the same as borax", as Bob Brandl states. While they will indeed prevent oxides from forming, they do not dissolve any existing oxides and carry them out of the weld; borax does both.

[Bob Brandl]

My bad. Borax does float some of the oxides off, and I didn't think about that part because of how I prep the steel before welding damascus. Thanks for pointing that out.

[JHCC]

Knowing how all this stuff works is part of the fun.