I'm Bored...

Someone say something! We need some dialog here folks.

Let's try this for starters- Jerry, you have someone doing field testing of some of your blades. What's the feedback so far on the S30V? Other than its resistance to fine finishing, is it all you'd hoped for?

Good topic. Fact is, Ron Simonich and I did our own testing, destroying some blades in the process. I also used an outside tester who has evaluated many of my knives and could judge how S30V performed comparatively, both with the knives I've made and from other makers. His testing included a lot of cutting and stabbing of different materials, ranging from paper to cardboard to wood to rattan to flesh and bone. I had made the point on that knife thinner than I normally would on a 12" blade, and I made the edge finer as well. Basically he tried to hurt the blade, using most any material someone would reasonably try to cut with it. The blade came back in the same condition in which it left my shop.

Based on one test I use as a toughness benchmark, it is almost as tough as 3V and the difference is probably undetectable by most users.

Bottom line, it is a VERY tough steel. I'd say if you live in a climate where the humidity is high and/or the air salty, or if you don't have the time to baby a blade, this is the high performance steel for you. Even though it has just 14% chrome, it is more stainless than 440C (17% chrome) because more of the available chrome is free and not in carbide form.

I'll continue using 154CM and my standard stainless because it is a lot easier to work and therefore less expensive to use, and CPM-3V simply because it is still the best, though not quite by the margin it enjoyed before S30V.

I am not, Ezboard is refusing my user name about once a month and then it sometimes is accepted again. But to business: how anout some exotic material combinations like: explosively welded Ti-SS-Ti or directionally solidified age hardened or MoC wootz or something really hard like BoN (that's done I guess) or diamond coating (also done propably), hmm.... what else can I come up with, nano_particle_metallurgy with cubic BoN, WC added.

Maybe not all seriously
TLM

S30V may not be nano-particle-metallurgy, but it is certainly micro-particle-matturgy. The average particle size is 2-3 microns before it's compressed. And better than Tungsten Carbides (Rc72/77), it's filled with Vanadium Carbides (Rc82/84).

A number if people are working on exotic laminates, Ti-Co-Ti, Ti-SS-Ti, etc. There are also some extremely tough age hardened and nitrided steels that are interesting. Wootz is very intriguing stuff, but nobody seems much inclined to destructive test some to find out how good it is in real life.

One of the problems with drawing any conclusions in this business is that most of the data is anecdotal. I've yet to see any testing done where there was just one variable being analyzed at a time.

VC is a bit harder than WC but apparently not as stable chemically, WC also is stiffer so in some cases that means better cutting. Both are quite sufficient for normal purposes. It seems that properties of various carbides have been studied for metal machining use but not much for cutting blades. Yes, wootz is often heard of but seldom seen properly tested and in the few cases where I have seen numbers those are not very impressive.

TLM

I tested one of my RWL-34 blades the other day....a 2" sheepsfoot blade..put the tip 12 in a vise and bend the blade 45 degrees and it went right back to true.....I flexed about 7-8 times and they all got back except the last 2...they left the blade a few degrees out...I could easily straighten it....tried to bend more than 45...at 50-60 it snapped ...

the blade was 60 Rc and cryo...I think that was pretty good..!

Why do we do such tests? Knives aren't prybars. What do these tests reveal? I seem to be getting only a confirmation of the quality of the heat and the heat treatment.

Considering the integrity of the participants in the current marketplace I, for one, would be willing to rely upon the certification of the maker or heat treating specialist for that.

Sam, I think for a maker it's a matter of wanting to know what the steel's capable of. It also confirms that the heat treating is sound, regardless of how well you might have thought it was done. QC I guess.

I've seen an ATS-34 fillet knife that I know wasn't heat treated very well bend 90 degrees near the point. It was very fine and didn't have a lot of pressure applied to do it. It's always intrigued me. What happens when one breaks and why. Is there a geometric configuration that would resist breaking under severe pressure? Probably so, that's why I-beams don't break. The more we talk, the more we listen, the more we learn, the less we understand...

Jerry, very profound. All good answers lead to more questions

Blade cross section geometry does have a lot of influence on the bending behaviour of the blade, some of it is not depending on material or heat treatment some is. It is also not too difficult to analyse if one knows what should be resisted, "the optimum" is elusive because you have to fix unnaturally many variables before it exists, or you have to be able to clearly numerically define something like "good enough". A flat ellipse is a good starting point and whatever the section, the only sharp corner should be the edge.

TLM

When I test a blade in the shop I don't apply a cheater bar and slowly bend the blade but rather hit it with a 4 lb. hammer and see how the blade reacts. If the hammer is recoiled back at me with no apparant damage to the blade I am satisfied. Of course this way I have no way of measuring how far the blade bends but it seems to be a better test of the blade.

Am I going in the right direction or off in left field with this type of test?

Gary

It tests the ""springiness" of the blade fast, that is yield strength, not a bad test. It also tests that the blade is not too hard and shatters, not a bad test. On a given geometry bending test fairly accurately "measures" the strengths, hitting it -unless you know the deformation- is less well defined but if you hit a blade- so that it bends- hard and it survives without bending or denting or shattering that is not a bad test.

TLM

and CPM-3V simply because it is still the best

Jerry,
I've been following your posts on s30v. How is CPM-3V better than S30V?
Tracy

Without the chrome needed to make it stainless like S30V, 3V is much finer grained. That makes it inherently tougher and also allows it to take a finer edge.

On the questions of bending and banging blades, banging is a better test in my judgement. Almost anything that "tries" a blade in a manner approximating what it might experience in real use is more meaningful than the more showy tests that are often used. Shock is a great destroyer of fine blades. Hidden cracks and stress risers may not be seen with gradually applied pressure, but shock will find and usually enlarge them, causing the blade to break if it's going to. I've seen lousy blades bend a lot, because they were thin enough to bend under modest pressure.

The toughest stress test I do is to pound a 10d nail into a board and bend it to 45 degrees. I then chop straight down on the bottom 1" of the nail to minimum any springiness, applying as much lateral stress on the edge as I can muster. Since it takes a reasonably fine edge to cut into the nail, you have a built in control of the edge geometry. Cut the nail without breaking the edge and you've got a tough blade - a combination of both edge geometry and steel integrity. The only blades I've ever made which passed this test without chipping were of CPM-3V. S30V did pretty well, but it chipped just a little - not enough to destroy the blade though.