The role of Nickel

[Christopher Price]

So first, a little set-up for context: I'm working a bar of damascus, composed of W2 and Iron meteorite (campo de ciello) which is iron with ~6% nickel and a sprinkling of other stuff. The billet is about 2:1 tool steel to iron, with a desired distribution of about 60 points of carbon.

 

After forging and welding up to a 32-layer stack, a sample was cut, further forged into a blade, and quenched in warm oil (5 minute soak at 1450). The iron in this sample had been at near-welding temperatures for almost 2 hours alongside the W2, yet remained soft after the quench.

 

So here's my curiosity. I've heard that Nickel is a barrier to carbon migration, but I've also heard that it neeeds to be nearly pure nickel to accomplish effective prevention of C migration in a bar of pattern-welded material, and that 6% was nowhere near enough to stop it. The empirical evidence suggests that it's not taking up the carbon effectively, though, and the layers post-forging are not what I'd call large in cross section. The rest of the billet I intend to do two triple-folds to get it close to 300 layers, and the knife pre-form will be about a quarter inch thick.

 

I'm curious to know whether this increased folding, and thinning of the iron will get it to a point where it won't really matter, or if my C distribution is indeed being significantly affected by the nickel in the meteoric iron at 6%. I can say that just a few seconds under ferric, you get a brilliant contrast between the dark tool steel, and the bright iron in the test piece.

[Richard Furrer]

Try it again at 1550F.

The nickel should not matter for what you are doing.

 

Ric

[Christopher Price]

Just so I understand, you're suggesting there's enough C in the meteorite layers to harden, just not at that temperature?

[Bret]

how thick is the sample at 32 layers?

at 1/4 inch your still almost .008 per layer. I would imagine once you get your layer count up and thickness down you'll be good. carbon doesn't move that fast or far

[Gary Mulkey]

What percentage of W2 & Campo did you start with? The W2 has approximately .3-4% excess carbon for hardening. If you gave the billet enough of the W2 compared with the meteorite then you should get enough migration for a billet with enough carbon to harden correctly (after three or more welds). The 6-8% nickel in the Campo shouldn't effect the carbon migration.

 

I have made three billets with these same materials (W2 & Campo)and had no trouble hardening with 300 layers. (I used four times the W2 as I did the Campo.)

 

Gary

Edited October 16, 2014 by Gary Mulkey

[Gary Mulkey]

I just re-read your post and saw that your percentage was 2 to 1 of W2 & meteorite. Even with this percentage I would think that you would get enough carbon migration to harden sufficiently. How many times have you had it up to welding temperature? That's where most of the migration will occur.

 

W2 has a wide discrepancy in allowable carbon content. Do you know how much your W2 had to start with?

 

Gary

Edited October 16, 2014 by Gary Mulkey

[Christopher Price]

I didn't have specs on this material, so pick the average. It's been up to welding heat for hours now, I just spent the evening taking it from 32 to 300 layers with a few soaks in between hammerings to cinch the welds and move C as much as possible. The blade is forged out, under 1/4" at the thickest, forged thinner near the edges before rough grinding it out. I'll grind closer, and fit the guard before I harden it.

 

It is lovely material, I'll say that.

[MSchneider]

I had an interesting conversation about this with a materials scientist friend and he had a thought on what could be happening. At very high temperatures the nickle can form carbides which would prevent carbon migration. Given that the material is non-terrestrial and could have been formed at extreme temperatures it is possible that the small % nickle formed carbides and is thus preventing the carbon migration. Just a theory, but I thought I'd throw that out there...

[Christopher Price]

Lots of interesting ideas out there, for sure. I really ought to just email Mr. Cashen about this.

[Jerrod Miller]

I had an interesting conversation about this with a materials scientist friend and he had a thought on what could be happening. At very high temperatures the nickle can form carbides which would prevent carbon migration. Given that the material is non-terrestrial and could have been formed at extreme temperatures it is possible that the small % nickle formed carbides and is thus preventing the carbon migration. Just a theory, but I thought I'd throw that out there...

The nickel carbide (Ni₃C maybe?) theory is that while carbon can move relatively freely (compared to bigger atoms like Fe and Ni) once it is bound down with a bigger atom or 2 it isn't going to move at all. Therefore any formation while in space would just be binding up pre-existing carbon and not account for the apparent lack of migration from the W2 to the Campo. Personally, I don't think nickel carbide (there are apparently multiple stable forms) is likely to survive forge welding thermal cycles.

 

Chris, did you try again at 1550 like Ric suggested before more welding?

[Christopher Price]

I've not hardened anything yet, just welded it up to 300 layers and forged to shape.

[R. Yates]

Chris,

 

Try the 1550 Degree F soak time for two Minutes letting the steel cool to room temp (On Its Own) them Temper @ 400 Degrees for a X2 Cycle letting the steel cool back to room temp (On Its Own) On the last Temper Quench in a Bath of Oil with oil temp @ 250 Degrees and it should stay in the Oil bath with out heat source to the Oil and Both the Oil and Steel Let cool to room Temperature You will see a Very Sweet Blade with Exceptional Hardness & Temperament .

 

Ret, Sgt. Robert D. Yates

[Christopher Price]

At least the welds held, not something I was sure would happen until I got into it. There were a couple times it seemed to fight me.

 

[stuart davenport]

Nickel is a NON carbide forming element. "Steel Heat Treat Handbook Second Edition George E Totten, PhD FASM". It will bond with Cr, Mo, Nb. I have read that steels with Nickel and Chromium rival the wear resistance of Chromium Vanadium steels.

Edited October 18, 2014 by stuart davenport

[R. Yates]

Looks like a Very Sweet Blade Chris. I look forward to seeing it completed .

[Jerrod Miller]

Nickel is a NON carbide forming element. "Steel Heat Treat Handbook Second Edition George E Totten, PhD FASM". It will bond with Cr, Mo, Nb. I have read that steels with Nickel and Chromium rival the wear resistance of Chromium Vanadium steels.

Nickel does indeed form carbides; a Google search indicates that most of the research on this is with nano-particles. It just doesn't like to do it nearly as much as other things in steel, like iron and chrome. One would be better to say it doesn't form appreciable carbides in steel. All the carbon has better things to do than form up with Ni. Good point to bring up. Nickel carbide would only be forming with pure Ni+C, so only really applicable to us if we use pure nickel layers in a pattern. But again, the temperatures we use would obliterate them.