Jerry :
I guess I'll also have to find out what more than 3-1/2" of beef bone will constitute a measure of toughness..
Bone is fine, especially from a large mammal. My point was simply that the manner in which the material is cut has just as important an effect on how a blade will react as do the properties inherent in the material. You can for example split a piece of wood with the grain very easily, it is however impossible through the grain. Thus splitting Oak with the grain is far easier that going through the grain with Pine, even though Pine is far softer and weaker than Oak. Specific to Bone, is not quite as dramatic in how it responds, but similar effects can be seen to a much lesser degree with variations in method. For example if you cut through a piece of bone at a 45 vs if you strike right into it at 90, the blade experiences very different stresses. Even factors like the tension in the bone are important and can't be overlooked.
Bottom line though, if you want to guage a definate level of toughness you have to have a series of blades that result in a different level of damage when they experience the same stress and thus you can do a rank just visually or measure the edge damage in some quantitative manner. And even if you do all this, all you actually have come up with is a rank of the blades, it takes a fair bit of analysis to deduce from this a rank of the steels as you have to consider how the geometry of the blade, its balance and other handling abilities effect the cut. A very slippery grip for example will greatly increase the strain that an edge comes under.
These numbers were not measured on steel sections that even approximate knife blades.
Yes, this is why you will often see steels like 1095 out score everything even L6 for example in charpy values. 1095 is a shallow hardening steel (0.040" - 0.080"), however for knife blades this is full thickness for a large part of the blade, and only a small core won't reach full hardness, so you won't get the toughness you would expect based on those properties which says that 1095 at 64 is 10%+ tougher than L6 at 60 RC. Outside of this one aspect though, most material properties are normalized to eliminate cross section and thus the size of the piece does't matter, think density vs mass).
As for the comments I made regarding steel, in particular regarding A2, they were not based simply on reading the Crucible spec. sheets. I have used several A2 blades from well known manufacturers, discussed the performance with other people who have done similar as well as with several makers whose opinions I respect as they have done considerable testing (which I have confirmed when possible). As well the properties that Crucible has noted I have checked against many other sources such as Bryson's works and others. They are in agreement, which you would expect given that they are well defined properties. However as you noted, you can change these by the heat treatment, but the basic idea stays the same and you should get some manner of scaling across the families in any case. The point about selection is also very general, basically steels are designed to run at certain levels of hardness, the reason that you have a family (A2-A9) is that they are all optomized for different hardness levels (and other properties of course).
If you make assumptions on how a knife using a particular steel, tempered in a manner you don't know and may not understand if you did, using a blade and edge geometry you've never seen, in the hands of someone(s) you don't know, made my a maker whose work you have never seen and whose works is also specifically designed for each specific user, you will likely be more wrong than you can even imagine. It's also just a little arrogant.
There are upper bounds that can be put on all of these abilities, and some of them don't require knowledge about much of what you mention. For example cutting ability isn't significantly influenced by steel type or heat treatment, its just geometry, so even a basic visual inspection (or spec) will reveal the gross abilities (the only real exception to this is you are cutting something like thread where sharpness is the dominating factor, and you are using very shallow edge angles, ~10 degrees). I just got a custom recently and knew just after looking at it the blade would not cut the way I wanted. I didn't need to know who the maker was, the steel type or heat treatment, the edge was simply too thick and obtuse. I did test it with this edge as well as after sharpening, as it never hurts to check, but I had to reprofile it before I got the cutting performance I wanted.
Specific to the comments I made on S30V, no one is putting forth the perspective that CPM-S30V is going to be tougher or more ductile than 3V, or that it is going to have better low stress edge retention over than S90V. So it is obvious that it can be compared to first order against similar blades made out of those steels (comparing it so say BG-42 would be very difficult obviously) with a focus on those aspects. My point about the steel was that I would prefer 3V for blades that would be required to take large shock as it is tougher, and S90V for those that didn't, as it would give me better edge retention in low stress work, quite simply really. I don't see anyone actually promoting CPM-S30V as being able to achieve otherwise, nor does Crucible itself, except for the obvious monetary matters of course which would make it preferable to S90V for some people.
R.J. :
I don't think you have enough data on this steel yet to judge it so harshly.
It is what it is, to repeat " ... doesn't offer anything of interest for me personally". This is hardly a "slam" on the steel, but simply a reflection of the properties that I desire in a knife, I could say the same thing about ATS-34 and it has a huge market. I found out about this steel back in Oct. of 99, it was presented then as basically trading some of the toughness in CPM-3V to get more corrosion resistance, and wear resistance as a side effect, probably not the main goal. I was offered the chance to look at test blades when it was available, I was really not interested then nor am I now based on those simple rough performance goals.
Quite simply there are other alloys I would rather be spending time with, as well as looking at the heat treating of those alloys to maximize performance. Of course, if some knife maker starts promoting that they can get more toughness out of S30V than 3V, or more low stress edge retention than S90V then by all means it would turn into something I would be interested in looked at. However, R.J., I don't think that is in any way likely, do you? As I noted in the above, it obviously has a large market, I was simply stating that I am not part of it. This is hardly different than someone stating that they are.
-Cliff
