The real skinny on S30V.

Originally posted by Gator97


Not sure what is the exact number, I guess depends on the steel.
As I remember there was a post where someone mentioned 20% per HRC. Though it was about pure wear resistance, not the edge holding.
I couldn't find that post though. May be someone else remembers the same thing?
Click to expand...

Wayne Goddard was good enough to test edge holding of various steels, some cryo'd and some not, at various hardnesses, and he published his results in his "Wonder of Knifemaking".

Unfortunately, my copy is packed up ready for a move to another city right now.

From what I recall, Wayne postulates that edge holding is just barely enought to call it a "knife blade" at Rc52 for most steels (the non-steel CoCr / Talonite / Stellite type alloys being a noteable exception that proves the rule). At this low a number Rc52, most "steel" knives will only give a couple good cuts through rope before dulling significantly.

Harder means better resistance to edge rolling, and per a custom maker I respect due to his heavy research and use of high end materials, harder and the resistance to edge rolling also tends to help keep the carbides all lined up and "on edge" where they can make themselves useful in wear resistance for human hand-held knives. I.e., even the high vanadium alloys benefit notably in overall edge holding at higher hardness (if toughness problems don't creep into play).

There was a significant benefit to having 2 additional points of Rockwell C hardness in Goddard's tests... I'm thinking it was something like 20% as mentioned earlier. The issue is certainly not linear with RC scale for knives, i.e. certainly not 2/60 or only 3.3% or something.

Harder is better in terms of an edge's ability to stay aligned, stay upright, the problem is toughness... i.e. brittleness creeps in enough to be detrimental for human use of knives held in human hands, in terribly general terms, past Rc58-62 depending heavily on the material at hand (examples might be a max near Rc58 for 440C, and maybe Rc62 for M4 or CPM3V, admittedly very subjectively)

So again, generalizing substantially, if Rc52 is the bottom end for steel knife blades, and Rc60-62 is the top end before brittleness issues come into play for even general use (not heavy chopping/prying type use) type carry knives, that continuum between 52 and 62 says that 2 points is a notable difference in hardness, and not trivial or negligible as at least one post suggested earlier. I.e, 10 total Rc points spans "barely a knife" all the way up to the upper end. That is part of the reason for the questions to CRK around their choice to back off Rc60-61 for BG-42 and dropping down to Rc58-59 for S30V. That is a 2 point drop, admittedly with a different and higher vanadium steel.

Again, the typical maker specs a hardness as a range, with a one point spread indicating the general lack of repeatability when either a different batch is run through an otherwise identical heat treat, or it indicates that if a given blade is tested at multiple points along the blade, multiple hardness readings across the blade nearly always result. 2 point spreads (Rc 57-59) are also common but may also indicate larger batches in commercial ovens by production houses, etc. I would think most custom makers or high quality commercial treaters would typically see a 1 point spread (e.g. Rc 59-60).

As a side note, and again from respected makers and heat treaters, for a 4" or less general purpose blade, all of these steels perform at their optimal at Rc60-61, and running any lower for a 4" or thereabouts knife is to give up performance unnecessarily:
ATS-34, 154CM, BG-42, D2.
 
Well I guess that proves it. Chris and Crucible don't know what they're talking about. Once people start to realize how crummy S30V is at 58-59, that should make my Bg-42 Sebenzas way more valuable.:rolleyes: :barf:
 
Ok, let's repeat one more time since previous 55 times wasn't enough.

Nobody says 58-59 is crummy or bad, the point is that for 3-4 inch long blade 60-61 would've been <b>Better</b>, unless we all miss something very important :) That's what Crucible said, that's what the makers say, etc, etc...
 
:D
Hello Sebenza fans!
Just registered, so I'm not really into the swing of this. But I thought I'd just announce myself. I've only got one sebenza so far (large lefthanded with a BG42 blade) and all I can say is "wow". And now I read that S30V is better!! I'm gonna start saving NOW.
 
I think the answer to all this is in Rob's post. Rob says, "About the lower rockwell hardness, it is much easier to get a good finish on this steel at 58 Rc than at 61Rc, at least with the equipment and abrasives I use in my shop." Big D1
 
Does CRK not follow this forum anymore? I haven't seen any response from Anne or Chris on anything in a while. I hope everything's OK up in Idaho.
 
Did they go to the Oregon show? Maybe that is ... er.... distracting them, at least for this past weekend. And, uh... this week?
 
Thank you rdangerer, I just read the article and was going to link. Interesting stuff. According to Phil Wilson Rc 61 gave edgeholding abililties equal to or better than ATS-34-154 CM. After reading that article, it would appear that CR Knives is indeed selling S30v short in terms of performance by limiting its hardness. I personally don't know jack-freaking-squat about heat treat but I do believe Wilson knows a a few things about it.:) :)
 
This thread started a month and a half ago, and has had 4500 views... and yet no response at all from CRK?
 
Ok another car analogy:

Porsche 911 = S30V @ Rc57 = great performance


Porsche 911 Turbo = S30V @ Rc61 = out of this world performance


Now, if you could have either one at the same price (and you could afford it), what one would you take? (No brainer).
 
I thought it was 58-59, not 57. Don't make it worse than it is!
Here's a thought, although I don't know much about heat treating, so it might not be possible. But if you really like Sebenza's and you must have the S30V blade at Rc 61, maybe you could send off your blade to someone like Paul Bos, who could re-do the heat treat to increase the Rc - is this possible, or is the heat treat a one time deal only?
 
I'd say that Chris' answer back on page 2 pretty much says what needs to be said, especially with the testimonials I've read here that declare S30V to hold up better than BG42 in daily use.

The main contention seems to be over a couple of points on the higher end of the Rockwell scale and it seems to be getting more contentious as things progress.

While I'm no metallurgist, I have been selling these things for awhile now and, in order to do a good job at it, I've had to learn a bit about this stuff. It isn't rocket science but it isn't kindergarten either. Here are a few of the things I've learned:

1. Hardness is important but it isn't everything. Too hard can be as detrimental to overall performance as too soft.

2. a couple of points on the hard end are nowhere near as significant or noticable as a couple of points on the soft end.

3. Wear resistance is almost as important as hardness in keeping an edge and at the higher end may even be more important. Wear resistance is determined by granular structure and carbide distribution and is not, necessarily, determined by the RC number.

4. The most common complaint to makers, manufacturers and merchants is that good knives are TOO HARD TO SHARPEN!

5. The second most frequently asked question about any knife, (right after "How long will it hold an edge?") is "How hard is it to sharpen?"

The first three are pretty basic and understood by most people who are into knives and such. The last two, however, may not be as well known outside the maker/manufacturer/merchant ranks.

Now, if you consider the sharpenability factor into the overall performance profile and consider that, at RC 61, the average, general user may not be able to efficiently sharpen the blade and may even cause damage, trying to use improper tools and methods, maybe you can see the reason for backing off on the RC a bit. After all, not everyone who owns or carries a Sebenza, or any other knife, for that matter, is an expert at sharpening knives. If they let the knife get dull and can't resharpen it then, as far as they're concerned, the knife isn't performing up to standards.

If, OTOH, the difference in edge holding and cutting ability between RC59 and RC61 are noticable only in the specifications and sharpenability is significantly improved at the lower number, then the overall performance of the blade is improved and is actually better than it would be at the higher number.

Finally, what is there about CRK that makes it so hard to take what they say at face value anyway? All this teeth gnashing and demanding that Chris "answer up" (he did back on page 2, BTW) because of a specification when most everyone who has used the new steel swears by it and says that it outperforms BG42 is silly. Why can't his answer be accepted for what it is?

Yeah, I read the bit about the Porche 911 vs the 911 turbo but it's apples and oranges. Besides, most "average" drivers out there wouldn't be able to handle the turbo or wouldn't be able to get the full potential out of it anyway. They may want the turbo but they really shouldn't have it. Same thing for RC61 S30V. It may sound better in discussion but is it really?

It seems to me that the major nit being picked here is the difference of a couple of numbers on the Rockwell scale. I'd say it was a tempest in a teapot, myself.
 
You have some very good points Dennis. And after talking to a maker, what CRK is doing makes more sense. The way he put it (my words, my understanding, though) is instead of getting a large but probably unnecessary increase in edge holding but only a little increase in toughness at Rc61, you get a huge increase in resistance to chipping, increased edge holding, and easier sharpenability at Rc59. And besides all that, S30V has significantly greater corrosion resistance than BG42 over the entire range of Rc (58 to 61).

submitted for your collective review :)
 
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