San Mai layered construction: Why not more?

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VorpelSword

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On another threaD, I got wrapped up in a discussion of knife steel formulations and a chart of edge retention vs toughness etc. Learned that I don't know enough to ask questions that really matter, though every one there was very nice.

But that thread broughtg up thoughts related but tangent to that topic about toughness, hardness and edge retentin . . .then I watched a few entertaining videos on Damascus (pattrn welding) forging. Just because a knife is forged from different steels does not men that the blade is superior in any way or even thsat it is servicsble as a knife; this from another thread on Damascis.

So these things just burbled around as the coffee maker made happy noises this morning and this thought popped up: Why not forge a knife from only three layers of steel? One layer that can take and hold a superior edge, but is perhaps less durble, hen put a layer of really tough steel on each side? Clocked round a little and found tat this is actually a named technique from Japan (match)called San Mai! And a few productin makers do usit . . .Cold Seel for one.

So the question is: Why is this technique not used more often?
 
VorpelSword said:
So the question is: Why is this technique not used more often?
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I'm sure you'll get a variety of answers, but IMO the most likely reason is that there are many modern alloys of steel are as good if not superior to the traditional San-mai blades. Today, the only real reason to play with multi-layer construction techniques for knives is for visual appeal.
If what one is going for is actual performance, then there are modern alloys that perform as good, if not better, and one doesn't need to go through the extra steps of forge welding a laminated blade.
 
I'm a big fan of the appearance yet I make it for the properties of the core.
These are the old 1095FG that Aldo Bruno sold before the lift off of NJSB. It had a nice dab of manganese for the black and vanadium for.......well..........vanadium.
Lp9YGin.jpg

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H84TU54.jpg
 
weo said:
I'm sure you'll get a variety of answers, but IMO the most likely reason is that there are many modern alloys of steel are as good if not superior to the traditional San-mai blades. Today, the only real reason to play with multi-layer construction techniques for knives is for visual appeal.
If what one is going for is actual performance, then there are modern alloys that perform as good, if not better, and one doesn't need to go through the extra steps of forge welding a laminated blade.
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This. Also Lynn Thompson supposedly patented the term San Mai and apparently defended it vigorously in court in the past, which may have kept others from bothering. It is pretty cool though. They used 420 outer layers, with either AUS8, VG-1 or VG-10 core. Wonder if there is a modern version that could claim higher performance?
 
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it makes sense to use this method if access to hardenable steel is limited, like back in the day.
nowadays, there aren't many good reasons for it, other than aesthetics and/or tradition, that I can think of 🤷‍♂️
 
Well, I was thinking less of dramatic looks and more of performance.

After looking at a chart of toughness vs edge retention (toughness increasing going up and edge retention increasing from left to right) I thought what if?

What if one of the steels from the lower right (high edge retention but easy to break) was sandwiched between two layers of some steel from higher up but to the left, or tough but with less edge redetection? Not multi-layered, but a three layer sandwich. These are all "modern " high alloy steels, but with measurably different properties that, for each steel, makes them less than ideal for a general purpose blade.

Today, many (but not all) folks think that Magnicut is a pretty good steel , being adequately tough and with adequate edge retention.: or, more than good enough overall and better than many. But there are other steels with much better edge retention and still others that are significantly tougher. A three layer sandwich of steels from both categories is what I am envisioning: tough as nails and holds an edge forever (if one could ever get it sharp!). Pattern and drastic looks are the least of my thoughts here, but could be an interesting secondary factor.
 
It doesn't quite work that way.
An extreme example would be a steel that is very hard at Rc64 but is also very brittle. Sandwich it between two layers of 5160 - a tough and flexible steel.
The resulting blade will have a very hard edge ... but the edge will still chip badly and the core will crack if flexed any at all.

What you are discussing has been done to a degree for a long time. I recall all the rush 20-30 years ago to make blades with VG10/ZDP189/etc. cores and softer sides. These steels are still available from many knifes manufacturers and suppliers. The advantage was mostly hype.

I had a similar question a while back in a discussion with another knifemaker. I asked him why the thought that knives made with a tungsten carbide core and a simple stainless steel cladding were not taking over the marker? In theory, they would have an edge that would never need sharpening. The two main answers were that it would cost too much and it wouldn't be all that much better than using a good steel and excellent HT.
 
laminated steel is used frequently with japanese kitchen knives, tens of thousands of blades are made with laminated steel coming out of Japan

one reason is you can have a high carbon steel cutting core and stainless cladding, easy to sharpen and reasonably easy care in use

also Lorien Lorien softer cladding makes for easier thinning of the blade (during a sharpening session) over time

softer cladding is also easier to grind and finish.

and broadly speaking in terms of making a blade, a forged laminated steel blade is highly efficient to produce

https://imgur.com/a/c3lc3HD
 
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that hadn't occurred to me👍
 
I am getting mixed messages here . . .Some sa yes and some say no.

Laminating different steels with different properties to allow a hard edge in a blade that resists breaking has been done in Japan for centuries. This seems to be an effective technique when using traditional steels in traditional applications such as food preparation or one-cut decapitations.

Surely modern materials science can come up with combinations of existing modern steels that, when laminated, will behave in a similar way but with higher levels of performance.

Are the San Mai blades from Cols Steel any better or in some way less functional?
 
How much higher performance are you expecting above and beyond the VG10/ZDP189 combo Stacy mentioned earlier? You also have to remember, not all steels share the same hardening and tempering process, so the pool of likely steels drops significantly.
 
SharpBits said:
How much higher performance are you expecting above and beyond the VG10/ZDP189 combo Stacy mentioned earlier? You also have to remember, not all steels share the same hardening and tempering process, so the pool of likely steels drops significantly.
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Well sure. I get that.

That is why I referenced materials science . . .meaning metalurgists who actually know what is what . . .and some of them are schooling me here in this thread.

The bug in my head: If multi-steel lamination wasn't a valid blade smithing approach, the Japanese swordsmiths would not have done it with the steels available to them. . . .during centuries of active warfare. Given that history, today we have a much better understanding of steel and better control of the chemistry and process of making steel.

Magnicut is as good as it is, and pretty much in the middle of the charts; "balanced" as they say. In performance, I would be looking for a combined toughness/edge retention dt point somewhere higher and to the right of Magnicut on that chart.

Perhaps the making of knives is too much a niche craft, even for commercial production makers, to attract significant research and development by heavy hitters. SpaceX is going to the Moon and Raytheon is building cruise missiles. Maybe Anduril would look into this.

I am probably just howling at the moon.
 
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polish avenger said:
Gotta also remember that lamination is also a way to make your high carbon steel go farther. Soft iron surrounding a high carbon is big bang for small resources.
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Just check steel prices - there's not that much different between soft iron (1018/20 type steel) and high carbon steels like 1080. Look at even the price of AEB-L compared to low carbon steels. OR - am I missing something?
 
Ken H> said:
am I missing something?
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I think what the polish avenger was referring to was that hundreds of years ago (until modern crucible design and smelting techniques), high carbon steel was very expensive to produce by hand, and as such was extremely limited in supply.
It would have been extremely expensive to have a mono steel, high carbon tool.
 
VorpelSword said:
The bug in my head: If multi-steel lamination wasn't a valid blade smithing approach, the Japanese swordsmiths would not have done it with the steels available to them.
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It was for all practical purposes the only practical approach. They were doing the best with the limited knowledge, materials, and techniques that were available to them at that time in history.

The question shouldn't be why aren't we using old techniques with modern steels, but rather would they have used the same techniques (San Mai construction in this specific case) if they had modern steels?
 
You asked why san-mai shouldn't be superior top mono-steel. That was what I was addressing. In modern steels, the cladding isn't needed for strength or saving steel or money.

San-mai is a longtime favorite of mine and many other makers.
It has historically been used in many places and for over a thousand years. Japan, China, India, Scandinavia, Russia, Eastern Europe, and by blacksmiths in the early colonial US days.
It originally saved rare and highly valued high carbon steel by using less of it in a sword or knife.. Later it was a way to make a knife with varied attributes that would not be in the core steel alone ... particularly toughness against a catastrophic break in a weapon. It became a decorative method with suminagashi - damascus sided san-mai. As you have seen from people like Karl, it can be manipulated in forging to make amazing edge patterns. With all the variations, the main point is still a high quality core with different sides. In many cases the side material may cost more than the core, so it isn't just about saving money anymore.
One very useful attribute is it allows a cladding that would make a poor edge, like a damascus with nickel or copper layers. There are many stunning damascus patterns that while pretty don't make a very good knife. Add a core of W2 or a super steel with a compatible HT and it make not only a show winner, but a kitchen winner, too.
 
VorpelSword said:
Well sure. I get that.

That is why I referenced materials science . . .meaning metalurgists who actually know what is what . . .and some of them are schooling me here in this thread.

The bug in my head: If multi-steel lamination wasn't a valid blade smithing approach, the Japanese swordsmiths would not have done it with the steels available to them. . . .during centuries of active warfare. Given that history, today we have a much better understanding of steel and better control of the chemistry and process of making steel.

Magnicut is as good as it is, and pretty much in the middle of the charts; "balanced" as they say. In performance, I would be looking for a combined toughness/edge retention dt point somewhere higher and to the right of Magnicut on that chart.

Perhaps the making of knives is too much a niche craft, even for commercial production makers, to attract significant research and development by heavy hitters. SpaceX is going to the Moon and Raytheon is building cruise missiles. Maybe Anduril would look into this.

I am probably just howling at the moon.
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You have to remember that warfare puts a huge drain on resources. Look at the measures the US took during WW2 to conserve resources and put them towards the war effort. The Japanese were stretching resources as far as they would go. If they could have called NJSB and ordered whatever they wanted, San Mai probably wouldn’t exist. Outside of aesthetics in today’s world there really isn’t a point in it.
 
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