Cold Steel San Mai III Stainless Steel

[FlaMtnBkr]

So I am curious...How do they keep the inner layer hard (64 rc) and the outer soft (50 rc)? After the layers are welded together dont they have to be hardened? Do the different alloys have such a different composition that following the heat treat for the inner layer results in a soft outer layer? And isnt stainless steel at a lower hardness more prone to corrosion? Just wondering...

Ryan

 

[Rocinante]

Ok, Adam says I could get the same knife only better from a custom maker for the same price.

Adam .....(or anybody) want to say who that custom maker might be?

 

[Alpha Knife Supply]

Isn't 440B inferior to A? I also heard that B is no longer being manufactured.

The most famous user of 440B is Randall Knives. 440B is still being manufactured.

When properly heat treated (how many times have you read that ) 440A is a good steel except for a bunch of crazed knife geeks like us. 440B is better and 440A but is not as popular because of 440C. I personally know a knifemaker who learned to forge 440C into knives. When he was first making knives 440C was only available in rod form. Hs shown me a big bowie he forged and made into a knife. He then cut down a 8" diameter x 30' tall tree in his yard, chopped off the limbs and cut the tree into 18" sections. When he was finished the knive would still shave hair from his arm. I really like 440C but it was faded in popularity becuase of newer steels.

I think the steels compare:
AUS6A = 440A
AUS8A = 440B
AUS10A = 440C

My experiance has been AUS8A is easier to sharpen than 440B but that may be beacuse the 440B is harder. AUS8A seems to take a polished edge quite easily. I only have one knife with AUS10A (stainless Spyderco native) and it works well. I'd like to have a big fixed blade with this steel for testing.

How do they keep the inner layer hard (64 rc) and the outer soft (50 rc)?

The 420J2 cannot get as hard as AUS8A because of the lower carbon content. Concentrate the heat treating on the higher carbon steel and the lower carbon will end up softer.

I think using 420J2 for san-mai is a good use for a steel that is a questionable blade steel by its self.

 

[Adam DesRosiers]

This is a good thread. Thanks to Chuck for the metal info. Also some good questions here:" How do they keep the inner core hard and t he outer layers soft."
The carbon could migrate within the blade when it is heated for hardening. This could make the outer layers get harder, and robb carbon from the core defeating the whole purpose of the laminate. I can see the merrit of a stainless skin on a high carbon core, but is it worth the cost when a quality coating could achieve the same effect?
I could be wrong here, but san mai dates to a time before the advent of the great steels of today. these days, it seems more of a novelty than an actual performance issue. It can be a wonderfull way to decorate a blade with mosaic damascus while still having a high performance cutting core, etc.

As for a custom maker who will make a peice similar to this for comparable cost, there are a many. You can check the galleries by price, or post a thread requesting the info.
I would make a simple knife in this size range Including a differential heat treat,but without my usual, time consuming, hand finnish for only a little more.
I niticed that Michael Raider, in Washington state had some very reasonable prices on some similar peices. His website is : www.raiderblades.com

You may not, however find many custom makers who use Krayton for handle material.
Cold Steel offers good knives. If you really like the looks of this one you would likely not be dissapointed with its performance. I have used them myself, and like them fine. I have, however, never found a stainless that would cut like a high carbon knife. If they offer it in Carbon V, it would be a better knife.
Good luck, and enjoy.
Adam

 

[Alpha Knife Supply]

The carbon could migrate within the blade when it is heated for hardening. This could make the outer layers get harder, and rob carbon from the core defeating the whole purpose of the laminate.

From what I've been told, carbon migration is not a problem for stainless steels. I thought the elements in the steel prevented the carbon from migrating like it does in carbon steel. What do you think Adam?

Michael Rader, in Washington state had some very reasonable prices on some similar peices.

Michael Rader is an up and coming bladesmith. Buy his knives and swords now before he becomes famous and his prices go up.

I also recommend a knifemaker from Alaska. I watched him at an ABS cutting competition. In 2x4 chopping he killed everybody. No one was close to his time. I called him "The Human Chainsaw". He also makes great knives that are meant to be used. If I remember his name correctly it was Adam DesRosiers.

Adam, put your website in you signature so people can look at your work.

 

[Rocinante]

Hey, this seems to me to be one of the most honest and BS-Free threads I've had the pleasure to read.

I feel like I've been given a LOT of useful information, not just about the original question, but others too (because I'm really just starting to learn about the complex issues involved in choosing steel these days).

I do appreciate it.

 

[Cliff Stamp]

I can see the merrit of a stainless skin on a high carbon core, but is it worth the cost when a quality coating could achieve the same effect?

The San Mai laminates give similar abilities to stainless steels as differential tempering carbon ones, they make the blades more flexible and better able to take impact. They also have simiar tradeoffs in that the blade gets weaker.

-Cliff