Thread: San Mai question to the blacksmiths among us

Hi all.
I was always curious about different core/clad combinations people are using in their San Mai creations. Specifically I wondered why are there not many stainless steel / high carbon combinations?
It seems to me only logical to make, say, 1095 or O1 HC core with marine grade 316 SS clad around it - this way it would give you one great hard edge combined with highly resistant jacket.
Is there a problem welding them together? Or is it simply not worth the trouble as HC SS like 440C is good enough in both departments (I personally don't believe so, or otherwise every razor would have been done of it instead the high carbons)?

Hopefully someone far more experienced than me will come along to give a more definitive answer, but I *think* the main issue for San Mai is that the welding process itself will be tricky. Some folks have done it and lived to tell the tale, saying all you need is flux and heat as per usual. Others swear the only way it will work is in an inert atmosphere with all the edges tig welded to seal and even in a canister. So something tells me the weld itself may be problematic

While not much of an issue for San Mai, the nickel/chrome content also makes folding and drawing out a billet really tricky if it's pattern welded. Well, folding at least wouldn't be an issue, but drawing out may well be due to the alloys having quite different properties at the same temps. So let's say you have a 1095 core clad with stainless, and you get a good solid weld. When you then heat the billet and try to draw it out, the 1095 will want to move more at a given temp than the stainless, causing strain and possible fractures along the welds.

So I've heard tell of it done, but I've also seen others say they wouldn't touch it with a barge pole.

Curious to see what others have to say...

I'm not a professional blacksmith by any means, but there is an issue with carbon migration from the O1 to the stainless during heat treating. It can be done, but it is difficult to do in a home shop and get a decent edge.

There is a Japanese clad sheet steel (High carbon center, stainless outer) that has been around a few decades that some people use for knives, but it is processed by cutting and grinding to shape. I'm not sure how or if it is heat treated. I've only seen it used on what I would call a KSO (Knife Shaped Object).