Rutger wrote: ↑
Fri Nov 22, 2019 6:03 pm
attila wrote: ↑
Fri Nov 22, 2019 8:45 am
Fri Nov 22, 2019 7:35 am
Good chance that REX45 will outperform this due to the higher hardness...
I was actually wondering about this and what experienced users of both steels have seen. I don't cut enough to have noticed any difference, and the only K390 I have is a lightly used Urban.
I'm guessing 65-66 hrc Rex 45 would support a fine edge longer, but may be passed up by the higher vanadium+tungsten content of 63-64 hrc K390 in extended cutting scenarios. At the same hardness, I think K390 would win hands down, but I can't be sure.
If K390 at this hardness outperforms the Rex 45 that the PM2 sprint featured, I'll consider buying the former and selling my copy of the latter.
Super Steel Steve did some testing between K390, Maxamet, REX45 and HAP40 cutting cardboard. The REX45 results were pretty impressive in my opinion considering it has a lot less carbides in it.
If you don't wanna watch the whole video for the results i'll list them here:
________| HRC..... | Fine edge | Working edge
K390..... | 65.6HRC | 198.8ft... | 406.4ft
Maxamet | 66.2HRC | 189.9ft... | 362.2ft
Rex45.... | 65.7HRC | 178.9ft... | 331.3ft
HAP40.... | unknown| 130.3ft... | 251.8ft
Sadly we can't use bbcode for tables on this forum.
So K390 beats Maxamet if at similar hardness. Though most Maxamet knives are produced at higher HRC (68-69) so they beat K390 in most tests.
The surprising thing from this testing is that REX45 at similar hardness as Maxamet is within 10% difference of it's performance. Could be margin of error in testing even. So the extra carbides in Maxamet didn't matter that much. REX45 is like a Maxamet light in composition.
K390 has different carbides/composition so it performed better. But you could question how big of an impact the extra carbides will have if it is ran at lower HRC.
K390 beats REX45 at similar hardness here, but the differences aren't huge in my opinion. Now consider K390 being several HRC points lower in this PM2 version. There are even examples of REX45 Military's at 67HRC which would make the difference in HRC even bigger.
So unless K390 at lower HRC has some nice attributes in edge finish/aggression/character (like cruwear) i don't see why you would pick it over Maxamet or REX45 at much higher HRC. Certainly not for the fine or working edge holding.
I have seen that video when originally released and rewatched the results discussion a couple of times since. That's what got me thinking.
K390 only leads by 11% in fine edge holding but by 22.6% in working edge holding.
I was wondering if dropping K390 by 2 hrc points would bring it down below Rex 45 in either working or fine edge holding or in edge stability.
These questions I can't answer, but BBB's explanations above helps me get a decent idea. Considering that and the amount of carbides in each steel, I still would expect K390 at 64 hrc to outlast or at least match Rex 45 at 66 hrc in the working edge department.
I like mine to stay shaving sharp, so the working edge characteristics aren't as important.
Have: old S30V Native, HAP40 Endura, ZDP DF2, S110V Manix LW, Cru-wear Para 3, SE H1 DF2, S90V Native 5, K390 Urban, SE Pac Salt, P.I.T.S., XHP Manix LW, SB Caly 3, B70P, PMA11, K03, Kapara, REX 45 Military, 154CM Manix LW, Swick, AEB-L Urban, KC Cruwear Manix, M390 PM2, Mantra 2, CruCarta Shaman, M390 Manix, K390 Police 4, S90V Manix LW, Rex 45 Manix LW, 20CV Manix, Rex 45 Lil’Native, Shaman, C208GP, Cruwear Manix, Cruwear Manix, M4 Chief, Z-max!!!
Want: SPY27, K490, Swick 5.