Howard Clark bldae specifics

C

Cliff Stamp

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Does anyone know the hardness specifics that Clark obtains on his blades? Is the entire blade Bainite, or just the spine?

-Cliff
 
On his L6 blades, the spine is bainite while the edge is martensite. I do not have specific current numbers, but according to his site (http://www.mvforge.com) the edges are between 57-58 with a body around 48-50 RC.

Hope that helps a little.
 
Cliff,

I've always wondered how bainite would perform in one of your tests. FYI, he has done bainite heat treat to other steels like 5160, and I think O-1 as well. In Blade Magazine last year Larry Harley won a cutting contest with a L-6 bowie heat treated by Howard. It was all bainite at 57 HRC.

The bainite/martinsite treatment he does for katanas is necessary for that hamon line look, but is not a requirement for a simple cutting blade.
 
Wouldn't R57-58 be inclined toward chipping in a sword usage? I guess it might depend upon the steel, but that seems pretty hard for a sword edge.
 
I've heard incredible things about these L6/bainite blades of his, but I haven't seen a full fledged test report. they say they are almost indestructible in normal, even rough, use. It must be susceptible to rust, though. Boy would I love to get my hands on one.
But they certainly are not cheap, except in comparison to some of Clark's more traditional blades.http://www.mvforge.com/BE'sA.html
Modern Tool Steel (Crucible Champalloy or L-6). I make these blades for the martial arts enthusiast who wants performance and durability first and foremost. A thoroughly modern steel, it is given a proper Japanese sword size and shape for the correct feel, but there is where the similarities end. The heat treatment is strictly twentieth century, and provides a blade that has a body which is very springy at HRC 48-50 and a hard edge that is HRC 57-58. The result is a blade that cuts well, holds a good edge, and flexes instead of bending if the cutting stroke is not so good. They CAN be bent if sufficient force is applied, but it takes a great deal of energy to do so. (CC's translation "Get your cheater bars out boys. Long ones.") The hamon is not as "active" with this material and heat treatment. Under any semblance of "normal use" these blades will never bend and take a set, nor will they chip. If "tough" is what you value the most, this is the blade you want.

Representative example of what the hamon looks like on these blades.

L6 is no longer available as a blade only item. (effective July 6, 2001). The L-6 katana are now available exclusively through Bugei Trading Company, and only as a complete, finished sword, no more L-6 bare blades will be offered for sale.
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Originally posted by FullerH
Wouldn't R57-58 be inclined toward chipping in a sword usage? I guess it might depend upon the steel, but that seems pretty hard for a sword edge.
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Historical katana will often have edges exceeding 60RC, being full-hard and often times without stress-relief after quench. These blades were somewhat prone to chipping when they were used improperly, but then there were also truly great swords that had very hard edges that stood up to a significant amount of abuse.

Hardness is just a number in general...when you take a high-carbon steel and harden it, you can often get in excess of 60RC straight out of quench...but this state of martensite is unstable and can crack or break even from sitting still for 10 minutes out of the quench (think happy thoughts for those 10 mins if yer not gonna stress-relieve). When stress-relieved post-quench (low temp, longer soak usually), you lose maybe 1 or 2 points of hardness, but the stability of the edge is vastly increased. It may only seem like a couple points shy of some hard knives, but 1-2 points can make a world of difference, particularly when done properly.

It seems really hard and brittle if you're comparing it to a lot of modern European-styled swords for sure, but it is a perfectly feasible hardness range for an edge, so long as you're not whacking rocks (and in the case of Howard's blades, that may be OK too--not that I'd ever recommend it!)
 
tallwingedgoat, I have heard some pretty strong statements about bainite recently, it does look interesting, especially if you can get 56+ RC. The problem is however, that martensite in a suitable steel at that hardness level is also very tough. There are not a lot of people complaining about chipping in O1, 5160, L6 etc., when it is 45-55 HRC.

Fuller :

Wouldn't R57-58 be inclined toward chipping in a sword usage?
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L6 is a fairly tough steel, and tends to resist fracture even at high hardness levels. It would depend of course on what you call "sword usage". If you are skilled enough, and restricted enough in scope of work, any geometry and steel can be functional.

Robert :

Historical katana will often have edges exceeding 60RC, being full-hard and often times without stress-relief after quench. These blades were somewhat prone to chipping when they were used improperly, but then there were also truly great swords that had very hard edges that stood up to a significant amount of abuse.
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Those last two statements are contradictory.

I have not used any of the high end japanese swords, but have used a lot of japanese blades, wood working tools mainly, with very hard edges. They are very easy to break because they are intended for a narrow scope of work by skilled users. When used in such a manner they excell over other choices.

Hardness is just a number in general...
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So is weight, this doesn't mean you can ignore it in a blade. The impact toughness of steels is very sensitive to tempering temperatures which have a large effect on the hardness.

Thanks for the info all.

-Cliff
 
To reiterate:

Many historical swords were left full-hard without any stress relief. This ends up with edges somewhat similar to a lot of woodworking tools and so forth. Edge damage is not terribly uncommon to see with these.

However, there are also swords with edges around or above 60RC that were very durable because of stress relief. It does not reduce the hardness of the edge significantly, but has a very significant impact on its durability.

As far as it being a number, I just want to make sure people don't rely only on an RC value to estimate how "good" something is. It has its place, but just like any other number, it's not the be-all end-all method of gauging quality or performance.
 
The edges on the quality wood working tools have all been tempered. However even after tempering, steels are not very ductile or tough once the hardness gets very high.

I can't imagine anyone selling untempered martensite blades. That is not even a stable structure and can be prone to shattering without the application of external force.

Of course hardness isn't the only sign of performance, however is it a fairly important one.

-Cliff
 
I would say if a smith makes a blade that isnt pretty tough full hard, right out of the quench, its not gonna be the best when tempered either.
Industrial things suck when full hard not only because of not being tempered but because they werent made greatly to begin with.

Stop by my shop when something fails in the quench; and youll see just how hellaciously tough full hard martensite(Ill further destroy it to view quality and strength etc.) *can* be. Im not claiming to be the best of smiths either, dont get me wrong.

I think light tempering can give a little more umph, sure, as martensite is unstable(pissed off to put it simply) and tempering can help it a bit.

Just rambling perhaps.

Joe
 
Gaben I just dropped him an email.

The main reason I was never interested in Bainite is that it is soft, 45-55 HRC. I have used many steels at this level of hardness, and even the more inherently brittle ones like D2, start to become very toughess with the martensite matrix is that soft.

At that level of hardness, edge damage will start to set in due to a lack of impaction resistance (hardness), and strength. Thus you will see edges dent and roll easier than they would at 58-60 HRC. Even if Bainite had a *MASSIVE* increaes in impact toughness over martensite at such hardness levels, it would not significantly effect performance because that isn't the weak point any more.

In fact with a properly chosen steel, I have seen plenty of blades at 58+ HRC that are still very tough and can withstand repeated heavy impacts (heavy shocks to the spine, like with a framing hammer), and the edge still tend to be damaged by deformation rather than fracture when they hit hard objects. I took my INFI Battle Mistress for example down to eight degrees per side and chopped knotty wood and the edge just dented to the side.

What I would be interested in was a steel which was as tougher or tougher at a higher hardness level. This would give the blade more resistance to denting and rolling and thus allow the creation of a more acute edge geometry for a given scope of work.

-Cliff
 
You should go to www.swordforum.com, there have been interesting discussions about bainite with Cashen, Clark and even me. L6 is very tough as martensite and even tougher as bainite. Cark is a true wizard when it comes to heat treating it,no one can match him.
 
I have been exchanging emails with Cashen for the last few days, slightly on Bainite but more on issues with Martensite. Very knowledgable maker.

-Cliff
 
i have seen work by Cashen.
amazing
beautiful work

i hear only positive thing about Cashen and Clark

i want a Clark sword, too

ZS
 
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