forging laminated steel

[Scott Roush]

I finally got my force air forge going and managed to weld up a 15n20/1075/15n20 billet.  The outer layers are 1/8" and the inside is 3/16" and it's 1 1/4" wide.  I'm not making damascus... just san mai.

So how much forging can you do with these things?  Can you treat it like a solid piece of steel??

[KHALVERSON]

scott
i have been thinking about san mai myself
but i need to get a forced air forge built first
it seems that if your welds are good you shoud be able to forge to shape without a problem
did you use anhydrous borax or 20 mule team
i cant wait to see how this billet turns out for you
kevin

[Scott Roush]

thanks Kevin....  I did use 20 Mule Team. This time I treated it like rare pixie dust.  In my other failed attempts I doused the billet with it and I almost wonder if the flux worked it's way between the steel and actually caused it to fail.  But I never got my venturi forge running anywhere close to the temps I did this morning.  I feel like I could though.... it would just take so much propane.

Anyway... I haven't even decided what to make from the billet.  I'm thinking a gargantuan bowie.

And I've cleaned up a failed 2 layer wrought iron/15n20 billet that I plan to put back in the forge tomorrow. I'm really excited about that combination...  but... I have no idea what I will do with it.  

but... again... I have no idea what you can get away with in terms of forging to shape.

[kbaknife]

Yes, you can forge it, provided your weld was good.
But, the neatest thing about the san-mai is how the two sides gradually disappear after final grinding.
So, you'll want to keep your forging to an absolute minimum, or you'll "push" the center out-of-center and then you'll have a wandering cutting edge that will be part 15N20 and part 1070 which will etch differently.
Take your time and gradually thin the blade out but do most of your final shaping by stock removal.
Try to see if you can watch the center as you go.
Most guys are using 416 stainless on the outside these days and a high carbon core like 1095. Once welded, they stick together great, but the different properties of stainless vs. simple carbon make them easy to differentiate during forging and it's easy to correct mistakes before they happen.
Your mix is going to be a little more difficult to observe.

[Steve Nuckels]

Thats way outta my league!

I'm looking forward to see what you come up with!

Good luck Scott.

Steve
--------
Potomac Forge

[Scott Roush]

thanks a bunch Karl... that is what I've been looking for.

[kbaknife]

I watched a demo on a san mai blade with 1095 core and 416 sides.
The 416 moves poorly - it's very tough.
As the sandwich was forged, we could see the 1095 actually squirt out between the two layers of 416.
So the different properties of the two different alloys was actually a visual benefit during the forging process.
When similar alloys like you mention are used, it will become more difficult to observe.

[kbaknife]

I forgot - using 416 stainless in a san mai, you can not use flux as in traditional welding.
You will need to stack the san mai billet up and then weld a weld bead all the way around the perimeter of the billet to keep out oxygen and thus eliminate any scale.
This is called a dry weld.
I've also seen the three pieces tightly wrapped in stainless steel heat treating foil, which, when done correctly, kept out enough oxygen to avoid scaling and contaminating the weld.

[Scott Roush]

In Haywood I spoke with Burt Foster about his stainless/carbon blades and he told me about his dry welding... and then I watched Bill Wiggins weld one up in Ohio doing that way. But he never forged it...he donated it to the auction and then it started to delaminate!

The thing I'm still a bit confused on is something that Bill mentioned... leaving little pores in the welds for gases to escape. I was never clear on how that was done.  However, I can assure you 100% that with the quality of my wire welding techniques, there will definitely be 'pores'.

[Scott Roush]

Well good news and bad news about this billet.  The good... it's a great weld. I cut a clip off the end and you can't even discern the layers.  The bad...  I'm not sure what I was thinking putting such thin outer layers on.  If I grind it the way it is, there won't be any outer layer.  Karl you mentioned that, but it didn't hit me until I started outlining a blade that, in my case, it would mean I wasted my time.  So... I'm gonna have to forge out the bevels as close as I can with minimal grinding I guess.

[kbaknife]

How thick is it overall?

[Scott Roush]

It's 7/16" total. At least it was.  I just forged out a blade from it and brought the edge down to just under 1/8".   I went ahead and forged the tip in just like I normally would do. But I started to get a little delam in the handle area when I started trying to draw it out. But the blade seems great anyway.

So we shall see. Good thing this was just a test, only a test.