Jason,

You have about three different dynamics going. Maybe more.

1: The wrought Iron itself ; Does it need to be refined by forging/folding

2: The rates' of expansion and possible disparities (potential for warpage is likely)

3: The compatibility between the wrought and your choice in high carbon steel as far as welding it.

I would consider each of these as a separate hurdle and address them ahead of time and increase your likelihood of success.

I recently attempted this without refining the wrought and it formed open rifts/splits along the length of the piece. It welded but the rifts are there and I doubt I can close them now. I will refine the wrought to a finer, closer, denser pattern(?)consistency before welding it to my high carbon on my next attempt.

Plan on warpage. Plan on it. That don't mean you cant use even forging and heating to mitigate warpage. You can and it will help, but it will likely warp. On the bright side, the iron will cushion the blade if you straighten it after your draw temp sessions and you can straighten fairly easily. Light cold hammering. Flat face.

I prefer the 10xx series steels for welding but either way, the tighter your control on the other factors, the more likely you will succeed at the weld.

Jason,

I've attempted this but once with many of the same difficulties that Lin mentioned. Something that you may want to consider would be rather than a san mai, to weld a high carbon bit into a blade of the wrought. This should help a little with the difference in expansion rates.

Also, count on welding the wrought at a higher temperature than what you're used to with steel.

Here is one I just recently did.

I used 3/8" 1095 and reduced my wrought to 1/4". I used no flux but did a dry weld just like all of my Stainless san-mai.

After a long welding soak I set the weld on my press large dies. I always weld the entire San-mai billet in one squeeze and never use repeated blows like from a power hammer..

I then drew it out using flat dies a little at a time.

I forged in the ricasso and drew out the tang on my power hammer with no issues.

It would probably hep to forge down the wrought at first so as to reduce voids, inclusions, etc. I ended up with a couple voids in the jacket which I do not like. I will not do another one for that reason.

Thanks, sounds like it'll be a challenge. I'm working on getting another rim to practice with before I go to the one from g-g-grandpa. The rim I have is fairly refined, but has one inclusion band that runs lengthwise. Other than that it's pretty clean. Looks like I'll have to mess with it a bit.

Also, no press. I usually set welds by hand, a couple of heats worth, then draw on the power hammer.

A bit late to the party but..... You can avoid the wrought needing to be refined by getting some triple puddle wrought. It has been refined enough to remove the greater majority if the slag inclusions. I found a stash of old anchor chain that was triple puddle. It is great for San mai but has very little variation or pattern to the wrought.

So I had this idea back in February, but just got around to it Monday. I took the rim up to a solid yellow and forged it out to roughly 1/4" thick. It was wanting to split a little along the edges, but no longitudinal splits. I forged it down to the same width as my 3/16 1084 bar. Then I MIG welded the seams all the way around the billet, two layers of wrought on the outside and the 1084 core. I had been welding regular 1084/15n20 running the forge at 5 PSI, and I cranked it up to 10. The billet was a little too long, so I welded each end separately at a high yellow. Seemed to stick well. Drew the 8" by 3/4" bar out into about 3/8 by 12, without hammering on the edges. Then I used the hand hammer and drew the bevel down a little, so I could get a better pattern on the transition line, and so I'd have less to grind. That's where I stopped for the day. So far, so good.

So a bit hit or miss on this one. I ground the blade to profile and all the welds look good. Then I milled the ricasso flat and parallel. I'm at around 3/8" thick there at the moment. I marked the center line on the edge, and put it in the ferric to check the centering of the core. Things got a little wonky. Plan is to put it back in the forge and straighten the tip area so that the core is straight, then grind or mill off the outer bends. I need to forge in the tang also. Hopefully I can get all that without messing up my parallel ricasso.

Edge looks good and centered till that last inch.

Spine gets a little wonky after the clip.

Plan after all the forging cleanup is to normalize and then subcritical anneal in the kiln, then try to harden. I'm on the fence about hardening method, but my inclination at the moment is to go with a low-ish austentizing temp of maybe 1450-1475, then full quench. Trying to get the edge good and hard without putting too much stress on the wrought and the welds. I've also considered torch heating just the edge to critical.

Regarding your final statement:

Why are you going to subcritical anneal before hardening? Good reducing heat thermal cycling is all you need.

And - you're not going to put any "stress" on the wrought iron or the welds. If you have good initial welds, heat will actually improve them

Try to avoid bringing the thicker areas up into austenite - the spine/ricasso. If you get conversion in those areas, that stress will want to rip the core in half lengthways due to differential phase change of the steel and WI.

Think "clay".

Be glad to just thermal cycle, saves a step. I'm not dialed in exactly on what sequence I prefer post-forging for my blades. I always thermal cycle, but I don't always anneal. Don't want to derail this thread that way, but I need to read some more.

Your explanation is closer to what I meant as far as stress goes. It's not the welds that worry me, its the core failure. Clay is a good idea, thanks. Lower austentizing temp and short/no soak?

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Be glad to just thermal cycle, saves a step. I'm not dialed in exactly on what sequence I prefer post-forging for my blades. I always thermal cycle, but I don't always anneal. Don't want to derail this thread that way, but I need to read some more.

Your explanation is closer to what I meant as far as stress goes. It's not the welds that worry me, its the core failure. Clay is a good idea, thanks. Lower austentizing temp and short/no soak?

Clay is your friend. If you sub-critical anneal that adds another step afterward. To sub-critical anneal means to spherodize all the carbon. That then needs to be brought back into solution, which is done by an extra austenizing step in most cases. Which can then require another grain refinement cycle before austenizing. So when you sub-critical anneal you may be adding as many as three more heating cycles.

Unless I'm doing lots of hole drilling, tapping, threading, etc. I just do three reducing heat thermal cycles - post forging - with the last around 1000 degrees so about all I have to do is austenize and quench when hardening.

Just avoid hardening the thicker areas and your core won't split. I use clay to avoid that.

So I finally finished putting this one together. Given the wagon san mai, I went with wagon rim for the guard, an 1836 half dollar for the spacer, and ash wagon tongue from Springfield Wagon Company, 1873-1951.

That is a very cool combination of materials. That knife is a home run.

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That is a very cool combination of materials. That knife is a home run.

Thanks, Karl. I sent it up to Coop for some glamour shots. There are a few things about it I'm really not satisfied with, but hopefully with a bit of publicity I'll get a chance to make another one that I am happy with <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />