Hey Drebs. In theory Cruwear should have better edge stability and toughness than CPM M4. Different heat treats can change the steels in a lot of ways including going for maximum toughness. Maximum wear resistance at the expense of less corrosion resistance. Hardness makes the steel stronger but less tough. Add in the fact that in this case the Cruwear mule is ingot while the CPM M4 is powder process and any of the attributes can change putting one ahead or behind the other.
By the steel companies books CPM M4 is ahead in wear resistance and toughness. Corrosion resistance on either one isn't great, but they are far from bad compared to some other steels I've tried that rusted much faster.
I don't patina on any of my knives. If I was the CPM M4 and Cruwear don't take patinas very well at all and come out pretty ugly compared to more simple carbon alloys like W2 and 1095 which can be actually blued like a firearm. The inherent corrosion resistance of these steels is what keeps the patina from applying evenly or effectively. You end up putting more time into forcing a patina than you would just keeping the blade clean and corrosion free. What patina you do manage to get will wipe off with use unlike the more , deeper blued effect of other steels. Aside from the chrome in both steels the heat treat can make some of the other elements sort of help out with corrosion, or abrasive wear resistance depending on how it ( M4) is heat treated.
I personally like both steels and plan on keeping the knives I have in both .
CTS B75P is a powder steel processed version of BG42 which is known to be extremely clean ( vimvar process cleans out impurities and inclusions). BG42 is a stainless version of the high speed bearing steel M50. It is essentially 154cm with added vanadium and is usually between 154cm/CPM 154 and S30V in abrasive wear resistance. It was pretty much the premium stainless steel before S30V was introduced. This was before the term "super steel" began being used around the time CPM 440V was introduced into production knives.
I have no idea if B70P is a "stainless Cruwear" as I've never tried it, or it's parent CRB 7, the ingot form. I've wanted to try it in a knife for a long time but until the mule it hasn't been very available. It should have good edge stability for a stainless. Perhaps that is why it was called "stainless cruwear". I try to keep speculation to a minimum though. Either above stainless should have lower corrosion resistance than 440C.
3V also has very good edge stability and strength in addition to it's toughness. A lot of people don't understand this when they claim 3V has no place in folders, just large choppers. If the kind of use one has makes the blade microchip instead of other types of failure a higher strength steel can be used. In some cases 3V can have greater wear resistance than higher carbide steels that fail ( get dull) from too little strength though this sort of use in a folder is fairly rare. W2, O1, 1080/84/85, super blue etc. are other steels with good edge stability. Traditionally high carbide fractions which give higher abrasive wear are less strong and tough at the edge where we concern ourselves in this hobby.
You sure are getting a nice collection pretty fast. It will be interesting to see in 6 months or a year which steel pushes itself to the top of your list.
Joe
