Molten Slag/Scale as Flux?

[James B]

Here's a quick question for an expert...  I get a good bit of molten slag or scale in my forge.  I've been forging meteorite iron and I'm not sure if the liquid in the forge is molten slag or molten scale or something else.  I use to think it was excess borax from welding, however in my new forge I get a good amount of this molten material and I haven't used any borax flux.  I typically scrape most of this liquid out while forging.  I'm surprised how much there is.  I keep the forge really hot because of the nickel content of the iron so I forge at welding temperatures pretty much all of the time.  A couple of questions:

1. Is this molten slag or molten scale (or is that the same thing)?  When it cools it's brittle with a much lower density than iron.  Would meteorite cause more of this material than normal iron?

2. I forge welded some pieces of meteorite without using borax flux.  I actually used the molten material to see if it would act as a flux and it squired out just like the borax flux does and it appears that I have a good weld.  Have you ever heard of that before?  Does this molten material help in anyway with a weld, or does it hurt the weld versus just cleaning the metal with a brush before putting it back into the forge to get it up to welding temperature?

Thanks!!!

James in Orlando, FL

[ThomasPowers]

Yes no maybe depending on a lot of factors.  Meteorites range from totally metallic to totally stoney where is the one you are using in that range?  (Need an official test report probably)  Scale generally melts at upper welding temps and does act to keep O2 from the weld area, but is not a very aggressive flux.   (Real wrought iron used to use the included slag as it's welding flux plus a bit of clean quartz sand if you wanted more---not an aggressive flux either!)

If what you are doing works for you then it's a "good" method.

[James B]

Thanks ThomasPowers!

It's a Campo Meteorite which is an iron meteorite with about 6.7% Ni and a little Co and P according to published data.  I also had a lab test it and their numbers matched almost exactly with that (7.0% Ni, 0.48% Co, 0.16% P, and 0.13% Si).  I had it tested after forging so I think I forged out some of the Phosphorus because that number was lower than the published amount.

It's good to hear it can be used as a flux (but maybe not the greatest flux).  I had accidentally welded it when I put the two bars together to get them flat before welding.  I put them on my hydraulic press and pushed them together at what I thought was a temperature slightly lower than welding temperature.  When I pressed it I could see the molten material get squeezed out, but then I couldn't get the bars separated, even after reheating and banging them around.  So I've been worried that the weld isn't good quality because there might be a layer of impurities.  I'd like to think my weld is good and I have no reason to think otherwise, other than I've never tried a weld like that and I was question my work.

Thanks again - it's great to have a resource like this with experts in the craft!

James

[ThomasPowers]

Solid Phase Welding can take place at room temperature---galling a bolt is a common example, as is explosive welding, vacuum welding, etc.

Basically there are 3 major factors: Heat, Pressure and Cleanliness; max any of them and you have a chance at welding.  Blacksmiths tend to use all three so we don't have to go to the max on any of them.

So if you had extra pressure and reasonable cleanliness you could get a weld at a lower temp than usual.