Ratio of core steel to side laminates.

[Jclonts82]

I’m making a set of 5 matching kitchen knives for 5 sisters doing 50-layer Damascus on each side, with a 80crv2 core. 

 

I have never done a core, and an looking for some guidance on thickness/ratios of the three layers. 

 

I know it varies depending on how much core you want, just wondering if anyone has any experience or what you had done in the past that worked well. 

 

 

Hopefully i can forge evenly enough to keep the core centered, and keeping the pattern even-ish from side to side. 

[Jclonts82]

Well I decided to just try it. Had my 25 layer pieces at about 1/2” thick. And the 80CrV2 is 3/8” thick. 

 

I went with 2 center pieces 80CrV2 and 2 cladding pieces at 25 layers each. So 1:0.75:1 ratio. It welded up just fine, consequently its the first forge-welding I've done without borax...  just clean surfaces, reducing atmosphere, and a soak in kerosene. 

 

 

[Bob Brandl]

Looks pretty solid. Well done. I generally do a thicker core vs outside bars when doing any kind of cladding or whatever, but didn't see this post before now. Sorry about that. You'll be fine for sure, but it helps to have the extra mass for the core of the billet. That's how I look at it, anyway. It has a lot more to do with what steels you're using than anything. I've done several stainless "san mai" blades, and with the stainless you have to account for it wanting to move less under a hammer at temp vs. your high carbon core, so you can get away with thinner stainless and a thicker core than you would think. With similar steels that move about the same, though, the thicker parts will have thinned out less than the thinner parts, so that's what you have "more" of when you're done with forging.

As far as a ratio, I always go with a 2:1 ratio core to cladding, and flip it if I'm more concerned about the cladding than the core. That said, I don't do a ton of precision forging when it comes to patterning, so take all this with a grain of salt...or three.

[ThomasPowers]

It's easier to be sure that the blade edge ends up in the "good steel" if the core is thicker.  Of course with perfect control in forging this is not a problem. Then carbon migration may be the controlling issue.

[Jclonts82]

I will post updates as I get the gumption to work in the heat of July in Southern AZ, and as days off permit. Its a good sized billet, after cutting the ends off I have a 20" X 2.5" X 5/8" bar. cutting that into 5 equal parts then forging, as identical as I can, blades from the pieces. I planning on an octagonal, hidden tang, similar to Japanese style kitchen knifes. but not doing the collar. a simple 3/16" stainless plate on the front that matches the handle dimensions.