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Cold Steel uses this type of three layer sandwich steel construction in some of its blades. I have read about what the company puts out on this and the idea of a harder center for the cutting edge and softer steel for the back and two sides of the blade for flexibility. I have had someone try to explain it further to me once. But, I guess I am just not understanding and do not have the engineering concepts to appreciate this type of steel.

I collect Boker Damascus Steel knives, as well, and think I have a real understanding of the purpose of the varied steel layers in Damascus blades. I have and have read the definitive book on the subject by Manfred Sachse and refer back to it from time to time.

I am aware of the arguments about temperature and merging of steels but the idea that an outer layer of flexible steel gives flexibility to the entire blade, I just don't get it. The outer layer may protect the harder inner layer but that is the only benefit I can see other than the aesthetic one of potential for a prettier blade.

Anyone interested in discussing this subject with the intent of educating me, would be greatly appreciated.

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Replies to This Discussion

Interesting Art and I have no actual idea myself. Would not a blade that's hard all the way through be better or does that mean it becomes brittle? And how do you get that layering exactly right?



Steve"Hog"Hanner said:

Interesting Art and I have no actual idea myself. Would not a blade that's hard all the way through be better or does that mean it becomes brittle? And how do you get that layering exactly right?

Well having said all that Cold Steel is selling a VG10 blade that has this exact San Mai process. Any chance you will buy one? I would love if you had a chance to review one if you buy it. I am kind of fascinated by the concept actually not knowing if it adds anything other than pretty!

I was just looking at another members photo of a striking San Mai blade. It was custom and not Cold Steel, but looked great.

I also wanted to include this link http://www.iknifecollector.com/photo/my-last-matt-bailey-san-mai?co...

This is a photo iKC Member Guy has posted. Interesting to note how artful this particular blade and knife is.

It is a beautiful knife that Guy has.

I currently own 3 blades from Cold Steel: master tanto II, Black Bear sub hilt and a 1796 light calvary saber. The first two have VG-1 San Mai III blades. These are sandwich steel but not that you would notice; that is they are not manufactured to look like any type of Damascus steel blade. They just look like fine knife steel.

All three of these knives are part of my collection and will never be used. So, I cannot really provide any type of review other than to say that I like these higher end Cold Steel blades and from a manufacturing, purpose design and aesthetics perspective they are far and away tops in their class.

Alas, in regard to my understanding of San Mai value in blade strength, I am still where I began, confused.

Art,

What I can find that is written in a way I can easily understand is:

A simple way to think of San Mai blade construction is to imagine a sandwich: the center is hard, high carbon steel and the pieces of bread on either side are the lower-carbon, tough side panels. The edge of the blade should be hard to maximize edge-holding ability, but if the entire blade was hard it could be damaged during the rigors of battle (remember this steel was constructed for sword). For ultimate toughness the body of the blade must be able to withstand impact and lateral stresses.

Toughness is generally associated with “softness” and “flexibility” in steel, so that, surprisingly, if a blade is made “tough” the edge won’t be hard enough to offer superior edge holding. San Mai blades provides a blade with hard (higher carbon) steel in the middle for a keen, long lasting edge and tougher (lower-carbon) steel along the sides for flexibility.

What I have done is also ask your question on the iKC Facebook page.  Maybe with all the activity on there from knife builders and makers we can get some more input

 

Thanks Jan,

Would this indicate that the "coating" of softer steel on the outside of harder steel gives the entire blade added flexibility? If so, is it by adding "protection" to the more brittle core or something else going on. Interesting.

Art 

Art,

Apparently there are several versions of it.  This is Rough Riders information for theirs...

The process starts with a core of carbon steel. Sixteen layers of spring steel are folded around the core, creating a "sandwich" of thirty three layers for strength and rigidity. The steel is then hand finished, giving it the unique appearance.



Jan Carter said:

Art,

What I can find that is written in a way I can easily understand is:

A simple way to think of San Mai blade construction is to imagine a sandwich: the center is hard, high carbon steel and the pieces of bread on either side are the lower-carbon, tough side panels. The edge of the blade should be hard to maximize edge-holding ability, but if the entire blade was hard it could be damaged during the rigors of battle (remember this steel was constructed for sword). For ultimate toughness the body of the blade must be able to withstand impact and lateral stresses.

Toughness is generally associated with “softness” and “flexibility” in steel, so that, surprisingly, if a blade is made “tough” the edge won’t be hard enough to offer superior edge holding. San Mai blades provides a blade with hard (higher carbon) steel in the middle for a keen, long lasting edge and tougher (lower-carbon) steel along the sides for flexibility.

What I have done is also ask your question on the iKC Facebook page.  Maybe with all the activity on there from knife builders and makers we can get some more input

 

There must be something to it as most if not all of the japanese samuri swords were made this way and we know they last 100's of years.I like the idea.

Knives such as san mai knives from cold steel use this layer prosess for giving the knife toughness and hardness so the blade does not break nor chip at the edge.I have a san mai tanto I use as a banger (EDC) and it has never failed me.It keeps a razor edge and does not scratch easy I recommend san mai I am a knife snob and I will say I love it.!!!

A blade needs to be hard at the edge or it will not keep an edge but a springe or tough spine is necessary   so it wont chip or break the trick is to get the perfect balance of the two. Makers have been looking the right combonation.
 
Steve Hanner said:

Interesting Art and I have no actual idea myself. Would not a blade that's hard all the way through be better or does that mean it becomes brittle? And how do you get that layering exactly right?

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