posted 06-11-2003 11:06               

quote:

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Originally posted by jwbirch:
...I asked why CRK used S30V for the GB knife instead of his proven A2 tool steel, which I understand to be a better choice for large combat/fighting knives...

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posted 06-12-2003 10:22               

quote:

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Originally posted by jwbirch:
...But would A2 at optimum heat treat outperform S30V at compromise heat treat?...

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Well yes, that is the $10,000 question. If it is any consolation, CRK's heat treat of A-2 was also a compromise on the side of toughness, 58 RcH, if I remember correctly.

posted 06-13-2003 09:12               

Knives are, first and foremost, cutting tools to be used by humans. If the knife is not designed from the steel up with that in mind, why would you waste money on it?

Generally speaking, any steel that has more than about 5% chrome is making a sacrifice in either toughness or edge holding in favor of corrosion resistance or some other dubious feature.
Even D2 runs about 12% chrome, and only holds and edge well when left really hard. Naturally, it's toughness goes out the window over 58HRC, and even with 12%+ chrome, it still rusts with the best of them.

IMHO, All of the high chrome stain resisting steels pretty much just suck as combat knives.

Further, too many of the vanadium carbides alleged to precipitate in S30V and other PM steels will reduce toughness dramatically, although abrasion resistance goes through the roof. Take a look at their last great attempt at the "ultimate cutlery steel", CPM T440V.
You'll find that although it has great abrasion resistance, at eight points lower hardness it has only about half the toughness of standard 440C. Why bother?

I am always leary of designer "cutlery specific" steels, as they tend to be heavily marketed repackages of something done long ago and since abandoned, or something new that answers a lot of questions that nobody bothered to ask.

Fad steels, like designer clothing fashions, are here today and thankfully gone tomorrow; but invariably replaced by the next big whoop te doo shamelessly marketed to the dedicated followers of fashion.

posted 06-13-2003 09:49               

Understand, I don't play with sharp things for a living but I do play with them all the time.

In my collection of toys, of the knives I use (hunting, camping, etc.) I only have TWO knives that are made of a single steel. One is made from an old planar blade (from Gates Rubber's old factory) and the other is made from the torsion bar from a John Deere tractor.

The planar blade we have no clue as to what the steel is -- it was given to me by a knife maker friend and I was asked to abuse it to death. I couldn't. But we have no way to reproduce it. Ditto with the torsion bar knife.

All the other knives I use tend to be composites (if that is the right word?). Some are Damascus, some are sandwiched, and some are folded.

These tend to hold up very well. And they combine some of the better qualities of each type of steel. For example, I have one knife that is a 5 layer sandwich (ala the Sweedish way of knife making) with the "core" being T440V, the next two layers out being ATS34, and the outside layers (where you see the flats of the knife) being a stainless that I forget.

Watching the knife being made I understand that it is a bitch and a half to get all the layers properly welded together, then it gets interesting when you apply a differential heat treatment (he had to use a jewelers green rouge to paint it sort of like the Japanese do with swords), etc. Maybe not mass production but effective.

So I guess I would ask those on this forum, why limit yourself to ONE steel instead of using composites or layers of steel with different qualities?

posted 06-13-2003 10:31               

Take the materials you mention for example. The core steel 440V is known to be highly stain resistant and wear resistant, but relatively low in toughness. This tells me that the knife is not going to be optimal as an extreme use knife because the edge will be susceptible to impact damage. The edge won't stand up well to chopping and prying, so why weld it into a sandwich of only marginally tougher steels like 154CM?

Weld 440V between tougher steels, and you've got a knife with an edge that will chip from extreme use and rust on the outside. The worst of both worlds. As Mad Dog alluded to with D-2, 440V is going to do best in knives designed for low stress cutting where you can leave the hardness very high for an edge that will last forever and won't rust, but would be vulnerable to damage from impacts or concentrated lateral stress.

Now if one made a san mai of say 52100 and L-6, I can see where you might get a blade that was tougher and more wear resistant than either single steel, but the complexity of producing such a blade would seem to be prohibitive compared to selectively tempering a homogenous 52100 blade to acheive similar results.

I have formed the opinion that san mai was created at a time when really good steel was hard to find. Good steel was used to form the edge, and easier to procure, lower quality steels were used to give the blade the required mass and strength. We now have lots of very high quality steel, so we don't need to do that any more.

posted 06-13-2003 12:20               

I have always been of the opinion (and it is just that and nothing more mind you) that 1. knives were specialized (so a knife I use to slice and dice I won't use to dig a hole with) and 2. no matter how tough the steel, it will chip/fail at some point -- so having a design that allows for controlled failure through techniques such as the differential heat treating, san mai, etc. gives superior durability.

While not a part of my collection (though I wish it were but I can only afford to keep what I use) I have seen old Viking swords with nicks cracks where the nick or crack ends where the watermark is. Ditto with old (1100's) Japanese swords where the chip or crack ends at the hamon - which is why you never see a straight hamon.

I do see your point though about having more quality steel available. Instead of controlling failure, prevent it in the first place.

Let me ask then your opinion on wootz steel. See http://metalrg.iisc.ernet.in/~wootz/heritage/WOOTZ.htm for a review.

posted 06-13-2003 15:36               

The primary question still remains whether you can accomplish anything with san mai that you cannot accomplish more simply with differential heat treatment.

Wootz is an intrigueing thing. It is essentially a carburization process as opposed to a welding process. It would be interesting to know how a Wootz blade would compare to a differentilly heat treated, high-carbon, low-alloy tool steel blade, but Wootz is so rare, we may never see such a thing done.

There was a company a few years back making Ti-steel-Ti blades that had good reviews for performance. Not good enough to keep them in business apparently, as they are no longer making knives as far as I know.

Mike Snody was experimenting with blades of ATS-34 and BG-42 with Cobalt edges welded onto them. This was the ultimate case of the weak edge on a stronger blade to me. I haven't seen any more of these attempts in the last couple of years.

Here is a doozy. Mick Strider, Ti integral handle and blade with a steel edge press fit.

posted 06-16-2003 14:10               

Neil

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Neil Ostroff
True North Knives
www.TrueNorthKnives.com

posted 06-16-2003 15:32               

Sort of like droping a copper penny in an aluminum boat I guess . . .

posted 08-14-2003 15:55               

I have knives in ATS-34, 154CM, 440V, 440C, S30V, and others.

I'm a simple guy; I use the knife. When it gets dull, I resharpen it. It cuts. I smile. End of story.

They each have their strengths. However, I think people people go way overboard with these "Steel Wars", overcomplicating the hell out of things.

None of my knives has ever given me a problem, and have done everything I ask. I just leave it at that.