Who knows what about 416 ss 1095 san-mai ala Bert Foster?

D

Djinn

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Feb 4, 2010
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I know there are additional complications inherant to this process over say high to low carbon san mai or pattern welded steel. How steep of a learning curve are we talking, and who has pulled this off?
 
Bert and Kevin have done a lot on this, and the learning curve was steep. The biggest things I got from listening to their seminars was that excluding all oxygen by welding the seams flawlessly, and dry welding the steels was what worked.
 
One thing I remember Bert saying is that you only have one shot to make the weld. If you don't get a good weld you have a paper weight.
 
You have one shot - one time. It's all about preparation, time and temperature control.
And you'd better toss in a large amount of humility, 'cause you're going to experience failures.
And I quit using 416 a year ago and have switched entirely to 420, after being educated by Ric Furrer, who is the source of this process. It's from Ric that Burt got the inspiration.









 
As a side-note to this San Mai discussion, the entirety of the undulations you see at the bottom edge of the 420 jacket is created using drawing dies.
I make no other actions to influence this edge other than drawing dies.
I know some guys cut into the billet after the initial weld to sort of create activity like in pattern welded steal, but what you see here is nothing other than drawing dies.
I say this, because it's a perfect visual representation of what is going on inside your steel when using drawing dies! :)
 
That is some beautiful stuff Karl.
I was lucky enough to have Burt close by me here to act as sort of a mentor... I know a lot of the issues he faced early on concerned finding the ideal temperatures for drawing after the initial weld. If you search thoroughly you will find some of his early posts, circa 2005, where he was working through the process and posting his findings along with the advice of others pointing the way.
You can also try to shoot him an email through his website. He is just an all around good guy, and may be slow to respond via email but is fairly open with a lot of his knowledge.
 
I use the same temp settings I use for forge welding.
Atmosphere is your nemesis.

nem·e·sis (nem-i -sis). n. 1. A source of harm or ruin
 
Yes - no flux.
I sit at about 2200 for 20-25 minutes.
There can be absolutely no oxygen.
If your steel even turns blue - it won't weld.
 
This was done with no pid. Just by eye and being careful. It's 416 cladding with 15n20 in between a w2 core. I use the wd/40 method to get rid of the oxygen in the billet. Lots of people do stuff like this. It's done in my shop on a regular basis.
E312E332-EB3E-4F75-9D99-679F150BDF64-6766-000005989AF028A6_zpsc2981cfb.jpg
 
The almost total lack of sulphur.
To make 416 the machineable grade of the martensitic stainless, it has 5X the S that 420 does.
416 is not MEANT to be forged or manipulated from its mill state/dimensions. It's meant to be MACHINED.
I'm not saying that 420 IS! meant to be forged.
But when you forge 416, with all that sulphur, it can and will - ask me how I know - rip or tear along sulphur 'lines'.
So as to avoid any of these unforeseen possibilities, and give my customers the best knife I can make, I have quit using 416 in my San Mai entirely.
I still forge down large rounds of 416 for my fittings. But have learned to do so very, very gradually. I have seen a 1 1/4" round of 416 with splits in it from end to end as a result of the sulphur and from moving it too much too fast.
So you've just got to go with small reduction steps.
That's alright when making fittings.
I don't want to roll the dice when making a working blade and have miniscule fractures that the eye can't detect.
I love doing San Mai and want to make the best blade I know.
And that does not include 416. ;)
Good query, Phillip. Nice to hear from you as well. :thumbup:


Phillip Patton said:
Karl, what's better about 420 SS?
Click to expand...
 
Karl B. Andersen said:
The almost total lack of sulphur.
To make 416 the machineable grade of the martensitic stainless, it has 5X the S that 420 does.
416 is not MEANT to be forged or manipulated from its mill state/dimensions. It's meant to be MACHINED.
I'm not saying that 420 IS! meant to be forged.
But when you forge 416, with all that sulphur, it can and will - ask me how I know - rip or tear along sulphur 'lines'.
So as to avoid any of these unforeseen possibilities, and give my customers the best knife I can make, I have quit using 416 in my San Mai entirely.
I still forge down large rounds of 416 for my fittings. But have learned to do so very, very gradually. I have seen a 1 1/4" round of 416 with splits in it from end to end as a result of the sulphur and from moving it too much too fast.
So you've just got to go with small reduction steps.
That's alright when making fittings.
I don't want to roll the dice when making a working blade and have miniscule fractures that the eye can't detect.
I love doing San Mai and want to make the best blade I know.
And that does not include 416. ;)
Good query, Phillip. Nice to hear from you as well. :thumbup:
Click to expand...

Thanks for the answer! Makes sense, although I've never had any of the problems with 416 that you describe, and I've been forging my guard stock for years now. The times I had laminates fail, it was the carbon steel layer that split down the middle. :eek:

Where do you get your 420? I've always wanted to try it, but never found any heavy round stock for sale...
 
So have I, Phillip. I've forged down what seems like miles of 416 rounds. I've even sold a bunch of 1/2" stuff to friends for guards. (And to the Blade Show)
With very few failures, I might add. :thumbup:
But we know how all it takes is a failure or two to change your method of doing things.
The two failures I had were because of sulphur. That's not questionable.
So, no more 416 in San Mai, and when forging for fittings, slowly but surely with good heat. :thumbup:

I've had two rips of the carbon steel core. That's been about three years now.
And didn't notice it until I went to do the final sharpening!! When I saw the cutting edge with a split in it.
Right in the actual dead-center middle of the blade.
After the knife was completely done.
Then quit until I figured out why.
I was not going to put that much time in a knife until I knew all about the various ramifications of that process.
And it's really pretty basic.
Regardless of the stainless jacket steel type, when thermal cycling, quenching for grain reduction, etc, there is an extreme expansion/contraction rate differential between the stainless and the tool steel such that the stainless jacket will literally rip the core from one end to another.
You just need to adjust your process/steps accordingly to do the right thing at the right time.
On a more positive note, this ripping effect does prove that you have a good weld!!!!!! In other words, the way I see it, if you weren't getting good welds, the two steels would rip apart at the weld lines. But this shows that the welds were actually stronger than the core steel. :thumbup:
I like that.
A lot.
I get 420 from the same place we seem to get so many other steels - Aldo.
I weld my billets with 1/4" 420 jacket and 3/8" 1095. Then draw those down to my finished dimensions.
I have lots of fun with San Mai. Lots. :D

Phillip Patton said:
Thanks for the answer! Makes sense, although I've never had any of the problems with 416 that you describe, and I've been forging my guard stock for years now. The times I had laminates fail, it was the carbon steel layer that split down the middle. :eek:

Where do you get your 420? I've always wanted to try it, but never found any heavy round stock for sale...
Click to expand...
 
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Phillip Patton said:
Thanks for the answer! Makes sense, although I've never had any of the problems with 416 that you describe, and I've been forging my guard stock for years now. The times I had laminates fail, it was the carbon steel layer that split down the middle. :eek:

Where do you get your 420? I've always wanted to try it, but never found any heavy round stock for sale...
Click to expand...

I've never had problems with 416 either. In fact I prefer it over 420. Not knocking anyone else, it's just personal preference. Also not saying I won't have any problems in the future :) but as of now its been good to me.
 
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