Stainless San mai

[parsha]

Hi Folks,

I came across some leftover stainless steel tubing. 304 or 316 can't say for sure. It's pretty thick walled almost 5 mm. The outer diameter of the tube is 1 inch and lengths vary from 4 to 6 inches.

I am thinking will it be possible to insert a high carbon core rod which fits tightly in the tubing, flatten the heck out of it in the forge and then cut it all the way in the center of the flattened billet to get 2 flat billets to turn into knives. 

Just a thought, dunno if it is doable???

My current setup is highly inadequate so I can't try this at the moment.

[Joël Mercier]

If I was to do this with my basic understanding, I'd weld both ends air tight to prevent chromium oxides from forming, hammer it flat and grind a fair amount of steel on the edge side to remove all of the outer jacket in that area.

[Brian Dougherty]

It might be possible, and it would be kind of fun to try.  I agree with Joel (sorry I don't know how to get an umlaut) about welding up the ends to keep the air out.

I've done some 304 and 316 welding to carbon steel.  In my experience, you have to get pretty agressive about grinding the surface clean.  I had one weld fail miserably because I just sand blasted the surface of the bar stock to get it clean.  It looked clean, but left the mill scale behind, and nothing would stick.  Ever since then I have used the belt grinder to make sure I got down to clean steel.

I mention this because getting the inside of the tube clean might be difficult to do.

[parsha]

Right Joel I was thinking along those lines. Some flux will also need to be added before welding the ends shut?

Thanks for the tip about the mill scale on the inside of the tube Brian and yes it will be difficult to clean that. Maybe I can use a round file to clean the inside or will have to fashion some sort of long shaft for the dremel and use a sanding drum.

[Will Drake]

My last try at doing a stainless san mai didn't turn out so well so feel free to take this with a grain of salt. If I were to try it with a tube though I would give this a shot

https://www.amazon.com/Lisle-10000-Brake-Cylinder-Hone/dp/B0002SQUG8

If you give it a go please post your results, and a WIP would be awesome.

[parsha]

I am hoping to give this a try . I understand that stainless San mai is not very easy to pull off like you said Will.

What high carbon steel will be best suited for this? By that I mean is there any high carbon which sticks better to stainless. I was thinking of a 52100 core rod.

 

[Brian Dougherty]

I'd stick with 10XX steels, but the real dictatting factor may be what you can get in round stock.

[Alan Longmire]

I agree with Brian here.  52100 has a lot of chromium, which makes for more difficult welding, especially with stainless which has more chromium still.  Yes, it can be done, and Aldo sells 52100 clad with 410, but it is not easy.  I'd use the brake hone and a piece of W-1 water-hard drill rod in the right size.

[parsha]

Thanks Brian and Alan. Time to head out and find some round stock high carbon.

[larsjacobsen]

If you clean your steel and keep them flat almost any steel will forge weld in a canister or with a seem welded around the billet ( san mai ) 

I have used O1, 52100, OFS ( old file steel ) , O2, White paper and stainless 316, 304, Aebl, 420......

I heat the billet at forge welding temperature for 15 - 20 min before the first weld and also for at least 10 minutes when welded or between welds. 

Steels have to be the right thickness in san mai .....if not the core will be either to thick or too thin or there will be way too much grinding on the outer layers. I still get this wrong although I try to keep a record of my works. 

I have never used a tube - so looking forward to seeing the result