Hand forged stainless San Mai?

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gudspelr

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Jul 1, 2013
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I've hand forged "regular" San Mai and also done some basic random pattern Damascus. I searched all over and haven't really come across anything posted up about hand forging stainless San Mai, though. Like a lot of people, I really like the looks of it and would love to try, but I don't have a press or power hammer. I have access to decent welders so I could (in theory) make some billets up and weld the perimeter. In my head, I feel like it shouldn't be a problem to apply the force with a hand hammer to set the welds, but I've also not done any forging of stainless steels....so I could be completely wrong.... I was hoping someone here could help me out with whether or not it's a likely possibility and if there are other things to pay attention to in particular when forging it? I know it needs to be hot and I understand some makers prefer to give it a little soak in the forge. I also know some makers only set the welds and get their thickness, then cut the blade profile out-others forge more to shape.

Thanks in advance for any help/suggestions.


Jeremy
 
gudspelr said:
I've hand forged "regular" San Mai and also done some basic random pattern Damascus. I searched all over and haven't really come across anything posted up about hand forging stainless San Mai, though. Like a lot of people, I really like the looks of it and would love to try, but I don't have a press or power hammer. I have access to decent welders so I could (in theory) make some billets up and weld the perimeter. In my head, I feel like it shouldn't be a problem to apply the force with a hand hammer to set the welds, but I've also not done any forging of stainless steels....so I could be completely wrong.... I was hoping someone here could help me out with whether or not it's a likely possibility and if there are other things to pay attention to in particular when forging it? I know it needs to be hot and I understand some makers prefer to give it a little soak in the forge. I also know some makers only set the welds and get their thickness, then cut the blade profile out-others forge more to shape.

Thanks in advance for any help/suggestions.


Jeremy[/QUOTE Jeremy, the man I know around here that knows about Forging Stainless is Devin Thomas, also known as Big Hoss!—————————- Chat him up one this..........That’s whom I buy my Stainless Damascus billets from.. The Best for you on this...
Click to expand...
 
I just attempted some stainless San Mai for the first time the other day. 1084 core with 410 stainless. I “dry welded” the perimeter as you mentioned and brought it to a bright yellow heat and went to town on it with my hand hammer. What I got was one of my patented Shit Mai bars, as I like to call it. It stuck in some spots, not in others. I learned what my problem was though. I tried to do too long of a piece. Also, I started hammering from the end into the center, flipped it around and hammered from the other end, into the center again. Needless to say, the center didn’t weld. So, I cut the billet in half were the weld didn’t set, and am gonna try and use some flux to get it to stick. If not, no biggie. I’ll try again with a lot smaller piece next time.

So my recommendation to you would be to start small. Like a 5in piece. From what I’ve researched 410 and 420 stainless is a lot easier to weld than 3 series.

You’re on the right track with dry welding around the perimeter. Make sure you seal up the billet. Set the weld at a fairly quick pace, while you have the heat. Good luck.
 
Flux isn't going to make stainless stick if it didn't the first time. Once oxygen and heat gets to the stainless, it won't weld.
 
Your challenges are multi faceted.
Truth is, if you had a good soak on the steel at welding heat and the pieces were quite smooth - like surface ground - you could probably get the first major weld done successfully in a vise with some jaw extensions to press the entire billet at once.
Then - bring it back up to heat with another good soak and do it again.
I'm not kidding you when I say this - if you have nearly perfect surfaces on your billet pieces and you weld that billet together while clamped tightly in a vise, you have a really good start.
Have your forge up to welding heat when you place the billet in.
Soak a good 15 minutes.
That alone may be giving you a weld. When you start beating it with a hammer you may be actually fracturing the weld. What you want to do is increase the weld you have - not fracture it apart. Use that vise method.
I've been making stainless San-mai since before I got my JS in '08 - I know what I'm talking about. In a decade I've had two weld failures and, of course, I was the fault both times.
Then you're going to have to figure out how to keep the center - in the center.
I start with 3/8" core and 1/4" jacket sides and draw out to final dimension.
I forge down on the bias to squish down my ricasso and draw out my tang. My welds are 100%. I've often said that anyone who will not upset-forge their San-mai for fear of delamination should not be selling it. I only saw cut the tip becasue that's necessary for me to keep the core even on both sides.
I'm just illustrating a little experience here.
You can do it - I just wouldn't want to do it all by hand. Soak time is crucial.
This is one I just finished for Atlanta - the second one is archival.
UyANS4D.jpg

CspJamL.jpg
 
perhaps a way for you to get started is with mild steel cladding instead of stainless?
 
Thanks VERY much for the great information. Karl, you were one that came directly to mind-I always love getting to see your San Mi blades. I have a decent sized post vise that I could put some jaw extenders on to try exactly what you’re describing.

And I’m all for starting small in regards to billet size... One thing I’m really interested in doing is making some to use for folders. I’m going over to visit John Doyle later this year and spend some time in the shop regarding folder making. Some nice looking stainless San Mai (in my head, anyway) would look pretty great in a folder. I’d also seen and thought about trying some San Mai that incorporated nickel sheet to at least add some visual interest, but I’m not sure about how it would do having a hard detent riding along softer material/cladding? I’ve liked the results I’ve gotten from 80CrV2 and was thinking about trying that with some 410 or 420 cladding.

Jeremy
 
Kuraki-that looks painful.... I saw some of those exact results when doing some searches (and seen similar results on San Mai with wrought iron, as well). Can you speak to what “makes” that happen (other than a lot of stress in differening materials)? It seems as if the same heat treatment (hardening) process gets used on two knives, but one cracks like that and the next one doesn’t. Are there things that can be done to minimize the issue? I guess I’m just wondering why they don’t all crack or put differently, what is done that will make the next one harden successfully with an otherwise similar/same procedure?

Again, thanks for all of the great information. This is super helpful.

Jeremy
 
gudspelr said:
(other than a lot of stress in differening materials)?

Jeremy
Click to expand...

That's exactly what that is.
Do the austenizing in a forge and only bring up the bottom 75% of the blade to full temp. Wherre the thin SS is will act like clay. Where the SS is thick will result in heat differential. The tool steel will be converting while the SS doesn't change at all.
If the exposed tool steel at the spine has been austenizied - you're in trouble. You can't control that in an oven - but you can in a forge.
 
gudspelr said:
Kuraki-that looks painful.... I saw some of those exact results when doing some searches (and seen similar results on San Mai with wrought iron, as well). Can you speak to what “makes” that happen (other than a lot of stress in differening materials)? It seems as if the same heat treatment (hardening) process gets used on two knives, but one cracks like that and the next one doesn’t. Are there things that can be done to minimize the issue? I guess I’m just wondering why they don’t all crack or put differently, what is done that will make the next one harden successfully with an otherwise similar/same procedure?

Again, thanks for all of the great information. This is super helpful.

Jeremy
Click to expand...

As said the stainless isn't austenitized at the cores aus temp and so the core grows more than the jacket. The jacket tries to hold it back eventually splitting the core from that stress. Karl's method above is certainly one way around that. Another is to cold peen the soft jacket before hardening essentially making it grow to match what the core will do. And get into the temper immediately. The blade i posted above didn't crack in the quench. It did that in my hands as i was cleaning it up post quench. If I had gone directly into temper it may have survived.

That's the advice Devin gave me. I haven't had the opportunity to put it to use yet.
 
I think I may copy and past all of this info just to make sure I never lose it... I use a propane forge for the forging and used to use it for austenizing, as well. But I built a salt pot and had planned to use that, since I do for all my blades now. That’s a really interesting way around the stress issue, Karl.

Kuraki, when you say cold peening, do you mean use the round part of the hammer and leave some shallow dings in the surface? In effect, creating more surface area that can “stretch” or grow as the core does? I hope that description makes some sense...

Jeremy
 
kuraki said:
The blade i posted above didn't crack in the quench. It did that in my hands as i was cleaning it up post quench. If I had gone directly into temper it may have survived.
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When it was in your hands was probably when it was converting to martensite. It would take almost 10 minutes for the blade to get up to tempering temp and that would have saved nothing.
 
Austenite is smaller than ferrite so when the core transforms at high temperature it shrinks. During cooling the sides cool first followed by the core. When the core transforms to martensite it grows because martensite is larger than either austenite or ferrite, putting the sides in tension, which is generally undesireable. Shot peening puts the surface in compression to help mitigate this.
 
Karl B. Andersen said:
That's exactly what that is.
Do the austenizing in a forge and only bring up the bottom 75% of the blade to full temp. Wherre the thin SS is will act like clay. Where the SS is thick will result in heat differential. The tool steel will be converting while the SS doesn't change at all.
If the exposed tool steel at the spine has been austenizied - you're in trouble. You can't control that in an oven - but you can in a forge.
Click to expand...

Can you put clay on the spine to help keep it cool?
 
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