Thomas, I too would prefer the steel to be run higher than RC 58-59 for a folding knife. RC 63-64 would be my preference. At this hardness it would be a monster steel as far as wear resistance goes, but still tough enough for most folding knife purposes.
IIRC, Phil Wilson stated something to the effect that S110 was as tough at that hardness as S90V is at RC 60-61, or something to that effect.
Phil Wilson stated:
Gentlemen, I like to use my knives in the field before I start to make statements on performance. I have not used CPM M4 yet but here goes anyhow. I have covered some this before so forgive the redundancy. CPM S90V goes back a while. It is still a very good steel for a light use hunter or even a fillet knife. It is best at RC61 but most times it shows up at 58 or so. This is a good compromise and favors a tougher blade for a wide range of users. CpmS110V was introduced as and upgrade for S90V. The improvements are in corrosion resistance and obtainable hardness. The addition of Niobium and Cobalt makes a very fine hard complex carbide. This steel shows up at around 58 RC-- at least the blades I have tested-. Mainly for the same reasons as S90V above. I have pushed it up to 64. At that hardness it seems about the same toughness as S90V at 61. I used a S110V (RC 64) knife on an Antelope hunt this fall. It held a scary sharp edge thorough the field dressing, skinning and quartering of 4 animals. I have a lot of experience with CPM 10V in the field both myself and feed back from others. As Sodak says this is the datum that I compare all others to. 10V is still my favorite for a utility hunter where use is not around salt water or very humid climates. My S110V hunter performed in the same category as 10V based on this one field experience. When pushed to the high hardness (64) there is some loss in corrosion resistance and toughness. This is illustrated on the Crucible data sheet. I left this same knife outside in the rain a couple of days and have not seen even a hint of rust. The conclusion so far is that it has adequate corrosion resistance to be equal to CPM S30V or S90V or example. I have not experimented with S110V at a lower hardness but feel confident at this time that even at 64 it has adequate toughness for a slicing type use. I would not try to chop or pry-- that is a whole different story and not the steel for that application. My cutting tests on rope show that S110V out performs S90V. This is logical-- 61RC vs 64RC. The downside of S110V is that it is pretty hard as supplied in the annealed state. Eats drills and belts up pretty quick. Grinding seems reasonable with the right abrasives. Finishing in the hardened condition is also probably worse than 10V. I believe it is in short supply, Crucible I think only made one heat and it is pretty much all gone. I have enough to last a while and hope there will be more offered in the future.
I just started working with CPM M4. The first blade came out at RC65. This is with high heat at 2160 and a 1000 temper. I do not have a handle on this blade yet. -Next few days- but did do some slicing on rope with a taped up tang. It looks to have great edge holding-- others have said here it is not as good as S110V but I don't know what hardness ect they are working with. Have to compare apples and apples. My sense so far is that it will cut about the same, have good toughness but the trade off will be corrosion resistance. Not a steel for wet climates. I also noticed that preliminary sharpening indicates this stuff will get very sharp. I hope next year to use a CPM M4 blade on a hunting trip and then can be more specific on how it works out... Phil
I can understand a production company not wanting to push it up this far due to a few reasons, including it eating more abrasives, and time both of which equal money.
Then there is the heat treat. Higher and longer soaks mean more costs, plus less element life. Some heat treaters won't touch anything above 2000 or so degrees.
Customers/end users. Not only do they complain when a steel chips easier, but a monster steel like S110 is beyond what most of them can or will want to sharpen. I wouldn't touch it without diamond sharpeners.
So, despite my liking every last bit of performance I can get out of a steel/knife combo I fully understand why a production company wouldn't want to touch it at these higher hardnesses.
To be honest as rare as that steel is I feel fortunate that Kershaw did a run of S110V shallots at all. I love them at RC58-59, but just like I would like my car , or motorcycle to be faster sometimes I have to be realistic.
There are people willing to re heat it to higher RC's now anyways for a fair price. Kershaw remains the only company to make knives from that superb steel as of this day. Thanks Kershaw!
I'd definitely feel luckier if my S110V ended up 60HRC vs. 58HRC...