Mokume delamination?

[effenoam]

I've had the same problem with my mokume(quarters) and pattern welded steel.  Which is, when forging the face everything goes great.  When forging on the edge(hammering on the visible stacked layers) my billet begins delaminating very quickly.  Everything looks good, check the edge on the grinder, then it splits.  Just to save you all some time, I understand the science but my skills and equipment is where I'm short.  Also, the mokume was hot when it split but not hot enough to crumble, the layers were solid when cold.

Any tips or ideas are appreciated. 

[oakwoodforge]

Can you post some pictures of the de lamination  ?   A couple things that help me are cleaning the stock really really well, to remove all oxidation I scrub with dawn dish soap/ hot water with a white 3m scotchbrite pad then wearing nirtile gloves I wash again with acetone before stacking the billet. The other thing is to make sure all  the pieces are cut clean and square with no waves or fish-hooks at the edges, any voids in the edges tend to be a spot for a de-lam failure to begin. I did try the stacked coin thing a few times with some success but have better luck with new, clean nickle silver, copper & brass. I haven't been brave or rich enough to try gold or silver yet.

[effenoam]

Unfortunately, I didn't stop to take a pic.  You're probably right about needing to clean it better.  It was just odd to me how it forged one way so well but not on the other face.  On every attempt of mokume or "damascus".

[Frosty]

There are easier metals to use than quarters. You have to work them dang HOT but getting them sanitary clean before welding is a must. I had luck flattening quarters on the anvil with a flatter then sanding the surfaces and applying a light dusting of borax before stacking them in the clamp. I found the difference between a successful weld and liquid copper alloy squirting out of the clamp was a narrow range.

Silver and copper diffusion weld like peanut butter goes on  bread. 

And no, I didn't forge a billet on edge, I made a sheet about 4" on a side to use as a dipper but didn't care for the pattern so it's somewhere in the shop unused.

Frosty The Lucky.

[oakwoodforge]

Just for grins, and because I hadn't tried the quarter thing in a while I spent a dollar on making this little guy yesterday for my wife.  Took the time to sand the quarters flat & smooth to 220 grit before doing the usual cleaning, I used a little borax paste for flux and a slightly rich adjustment to the gas forge, worked a treat.

[patrick]

The reason that mokume splits when forging on edge is because you are creating a tensile load at the layer interface. They want to spread side to side. When striking with the layer horizontal you put that same interface in compression. As was already noted, you really need very clean surfaces before starting the bonding process and then when you do forge with the layers vertical you need to used a technique that minimized the side to side spread. Basically you need to deform only very short lengths at a time. I've been production forging mokume in batches upwards of 100#s at a time for about the last 12 years and I've managed to make it fail in most of the ways that can be done.

Patrick

[Frosty]

Another thing to remember is even if  you have a perfect diffusion weld between layers, the different metals have their own range of malleability, elongation, tensile strength, etc. So even if the weld itself doesn't fail, the metal layer sure can and it'll usually happen right at the transition between the diffusion zone and "pure" metal. 

Is that reasonably close Patrick? 

Frosty The Lucky.

[patrick]

Yes that is true but if you're using a billet of copper based alloys such as brass, copper and nickel silver, those differences are not so big as to be the primary source of the problem. I didn't mention it above but most of the lay separations I deal with are on the very end of the billet where no hammering ever happens. The ends usually bulge out for me and this bulging creates a tensile load on the layers at the end just as it does on the sides. The difference is that since the ends are never struck that tensile load just continues to act on those layers as you draw out the billet. I usually end up trimming a little bit off to clear those splits before i start forging to and octagon, which is my preferred shape for twisting. The biggest risk I see for layer seperation aside from interfaces which are not properly cleaned before bonding is the shearing action that happens when you do go from square to octagon. I minimize that by taking tiny little die bites and very shallow drafts. If I do that right, I usually don't have catastrophic failures.

Patrick

[Frosty]

Yeah, if you don't hammer the ends they'll open like a book no doubt. Working at diffusion temps pretty well takes care of failure in a layer.

Have you tried octagonal swages, top and bottom for the transition? It'd cut the risks considerably. How about a roll press? 

May we see some pics of your Mokume please? 

Frosty The Lucky.

[patrick]

Frosty i provide a forging service for one of the mokume sellers who serves the knife market among other things so all my pics are just stacks of big billets in various stages of processing. The best pics of finished projects will be found on the website of william henry studios. Many of the billets i start with ate 2x2x6 or even bigger and they may weigh 10 to 12 pounds each so forging on the ends is not practical for me but could be helpful in other circumstances. I do all my work on flat dies with stop blocks. Im sure swages could be used. You'd have to work out the exact geometry to prevent forming laps. I wouldn't normally use square stock as input into a swage like that. Round would be better i think.

[Frosty]

I was just blue sky thinking, I get ideas all the time I can't help it. I didn't see anything to speak of on the william henry studios cutlery website though I may have picked the wrong william henry. Color anodized al or ti, cnc machined, screw together pocket cutlery sets. Do you have a link showing your product? PM the link to me if it's a commercial site, please. 

Thanks for indulging me,

Frosty The Lucky.