Also forget about finding the final answer here. This page is being constantly revised as I learn more about knife steels.
I am not a knife maker or a metallurgist. This is my own summary of what I have learned about knife steels. You can read about this topic at great length. Lots of people who don't know tell you what they have heard from other people who don't know.
At this point, I have two favorite steels. M4 is one, and M390 (aka CPM-20CV aka CTS-204P) is the other.
One thing is certain. Proper heat treating is as important as the steel itself. All that most folks can do is to select a manufacturer with a good reputation and trust that they have people who know how to get this done right. The design and manufacture of the knife is almost certainly more important than what steel the blade is made from.
What is the best knife steel? Why, S30V of course. This is almost an honest answer, the real answer is that "it depends". S30V offers an excellent balance of toughness and edge holding hardness. it has also been around a long time, people know how to work with it and get the best out of it. It is well proven. S30V is the steel to reference all others to. For a folding knife, S30V is ideal, other steels are good and there are some new steels that may be better. I consider S30V as the first of the "super steels".
Note that the "super steels" with high vanadium content hold their edge very well, but are correspondingly a real task to sharpen. It is best with them (and with any knife) to keep them sharp rather than let them get dull and then try to get them sharp again. It has been said that S90V and S110V are almost impossible to sharpen.
I classify steels into the following categories.
So you face a conundrum. Do you want an affordable steel that you can sharpen well (but need to sharpen more often). Or do you want a hard to sharpen steel that because you are unable to sharpen it, actually gives you a poorer but long lasting edge? The truth is that many people without advanced sharpening skills may actually be better served by a steel in this class than one of the super steels.
CTS-BD1 was made by Carpenter for Spyderco. Here is What Sal Glesser said about it:
Carpenter Steel created CTS-BD1 at Spyderco's request. We wanted an ingot steel that had good performance in edge retention, toughness and corrosion resistance, but was less to purchase and process than the powdered steels we've been using. Something we would use in our "basic" models to lower mfg cost (and retail price) and use in our kitchen knives. The closest chemistry to what we wanted was a steel produced by Hitachi called Gingami 1 (GIN-1, G2). We had much experience with the steel and have been importing it from Japan. I asked for something equivalent or better. They tweaked the forumla and game up with BD1, which was an even better performer than Gingami and was USA made. Carpenters metallurgists are first rate. BD1 has hi-powered trace elements in the formula ...
S35V is S30V with some niobium added. This makes it easier to machine, but is not especially better than S30V for the end user.
The thing about S30V is that it has been around a long time, is well understood so you can feel confident that people know how to properly heat treat it. S30V seems to loose a fine edge quickly, then keep an excellent working edge forever.
Note that the numbers in the S-series indicate the percentage of vanadium. S30V has 3 percent. S90V has 9 percent. S110V has only 9 percent though.
Also note that S30V is tougher and easier to sharpen (but not easy) than S90V or S110V. What you get with S110V is superior edge holding. The concensus seems to be that S110V is a tiny bit better than S90V.
Note also that many pocket knives get hardened to 60 HRC or so.
The 52100 Military was a sprint, the PM2 is/was a distributor exclusive.
Sal Glesser said:
It was a real PITA to find it rolled to the thickness wanted. It's also a bugger to work with in a production environment. Not too many production folders out there in 52100. I can see why.Someone said:
52100 will start to patina and even form rust spots just from chilling in a pocket for a few hours. The tradeoff to this is excellent wear resistance and sharpenability. I swear you could probably pick up a rock and get it hair whittling sharp with little effort. Then you can beat it on it like you would M4 and it won't care. It doesn't hold a freakishly sharp edge as long as M4 will, but again it's so easy to sharpen up that I feel encouraged to use it more than my M4 knives.People wish that the Nilakka would be made with 52100 instead of S30V. This is a unique folding knive with almost no edge bevel and a very thin blade. It is a folding rendition of a Puukko knife.
52100 is just a fun steel. It invites you to use it and it pays dividends when you take care of it properly. A lot of popular steels nowadays you can just abuse and throw in a corner. ... a knife guy is missing out if he doesn't give 52100 a go.
Tom's Knife Info / email@example.com