K390 IS "The M4 Killer"

[Deadboxhero]

About a year ago Doc Dan asked "K390, M4 Killer?"

I'd say, Yes.


While technically, K390 is more like 10v so not quite an apples to apples comparison, the k390 doesn't seem to lose any edge toughness to M4, while K390 impact/shock toughness may be a different story, I find it difficult to swing a folder like an axe.

This is wild because K390 will cut longer and hold a better apex than M4. While M4 takes a very nice edge and touches up fast, so does K390.

K390 is offered at a higher working hardness and has more carbide volume making it stronger and more wear resistant to boot.

I think the challenge facing k390 is that it's not as well known as M4.

It's also very expensive to buy the steel.

It's hard to get and is an import from Europe, so not widley available.

It's more expensive to make knives out of. The abrasive cost goes way up to finish and is a chore.

Also it's a carbon pm tool and will rust, so not for people that want stainless, yet will offer more edge Performance than a stainless. Trade offs


I highly recommend only using diamond/CBN to set the edge such a a Spyderco doublestuff 2 CBN. To get the most performance out of the steel.


I'd say if edge performance is more important than anything than the k390 is looking very hard to beat.





K390



M4

[Doc Dan]

I only have one knife in K390 but it is one I cannot do without. It is in my pocket daily. Out of all of the non-stainless steels I have used, it is by far my favorite. It holds an incredible edge and stands up to cutting things like nothing else that I know. I have not tried Maxamet, but I have tried many others that Spyderco and other makers use and K390 performs beyond any I have tried for my uses.

Thanks for opening this up, again. We need more K390, as far as I am concerned.

[Deadboxhero]

I only have one knife in K390 but it is one I cannot do without. It is in my pocket daily. Out of all of the non-stainless steels I have used, it is by far my favorite. It holds an incredible edge and stands up to cutting things like nothing else that I know. I have not tried Maxamet, but I have tried many others that Spyderco and other makers use and K390 performs beyond any I have tried for my uses.

Thanks for opening this up, again. We need more K390, as far as I am concerned.

I really like the Maxamet for the firepower but it's definitely not as durable as the K390

[DougC-3]

I believe Spyderco has used K390 in just three models, the Mule, Police, and Urban? I think it's really time to add a few more, starting with the Manix 2 and Manix 2 XL, hint, hint

[ZrowsN1s]

There's nothing "wrong" with M390, M4 (just bought 2 M4 knives), and 3V. But I feel like Maxamet, Rex45, 4V, 10V and K390 are better choices for a performance minded folder.

My Rex45 and Maxamet Para3's, my 4V Manix and K390 Police are amazing knives. Doesn't mean I don't love my M4 or S30V Shaman, those would have been the hands down nicest steels in my collection less than 5 years ago. I could have called it quits collecting and been good with the first two Spyderco's I ever bought honestly (S110V para2 and ZDP-189 Dragonfly), but I love to see the limits of what's possible pushed. The 'cutting edge' as it were. And as great of a steel as M4 is it's not the cutting edge anymore, it is the solid established edge.

Spyderco has been my introduction to most of the steels I've tried. I hope they keep expanding my horizons and the markets with more K390, 4V, Rex45, LC200N, Maxamet, 10V and dare to dream maybe one day steels like 15V, Rex121, Vancron 40, Vanax, and others I've only read about.

It's supply and demand. And if you don't demand it, they won't supply it :D

[bearfacedkiller]

While I do not buy into the idea that one steel makes another steel obsolete I do agree that K390 is great stuff and I want more. The Police4 is my only knife in it. I do also have the K2 in 10V which I also like. I want one of these steels in a slightly smaller folder. Bring it on!

Still super excited to score a M4 Shaman!

[elena86]

CPM-Cruwear aside, K390 is my favorite non-stainless steel. Superb display of qualities. My beloved K390 Urban is a little beast and it's my go to city carry. We really need more K390. I would kill for an UKPK in K390. Please Sal, throw us a bone :eek:

[blues]

If the Police wasn't the only alternative to my K390 Urban, I'd be all over it.

Especially if it was a model built here in the USA.

[TomAiello]

I only have one knife in K390 but it is one I cannot do without. It is in my pocket daily. Out of all of the non-stainless steels I have used, it is by far my favorite. It holds an incredible edge and stands up to cutting things like nothing else that I know. I have not tried Maxamet, but I have tried many others that Spyderco and other makers use and K390 performs beyond any I have tried for my uses.

Thanks for opening this up, again. We need more K390, as far as I am concerned.

I really like the Maxamet for the firepower but it's definitely not as durable as the K390

Do you mean K390 is tougher?

What is "durable" in this context?

[Deadboxhero]

I only have one knife in K390 but it is one I cannot do without. It is in my pocket daily. Out of all of the non-stainless steels I have used, it is by far my favorite. It holds an incredible edge and stands up to cutting things like nothing else that I know. I have not tried Maxamet, but I have tried many others that Spyderco and other makers use and K390 performs beyond any I have tried for my uses.

Thanks for opening this up, again. We need more K390, as far as I am concerned.

I really like the Maxamet for the firepower but it's definitely not as durable as the K390

Do you mean K390 is tougher?

What is "durable" in this context?

The edge was more durable than the M4 because the edge was more stable with a better combination of strength and tougheness

Toughness in a classically is impact/shock resistance. The ability to resist breaking with sudden force.

Technically the harder steel with more alloy is not able to be as shock resistant. I would not use K390 for an axe. The additional strength and alloy doesn't give the matrix room to move and absorb energy meaning it's more likely to break suddenly. However I can't swing my folder like an axe to take advantage of impact toughness which leaves me with an edge that is easy to deform when cutting.

I find that strength is a very important aspect for holding an edge in this regard. It gives the edge resistance to deformity.

The stable structures that form in K390 at high hardness appear to give it a boost over M4 in stability.

It not universal that a harder steel is always better.

Microstructure is key but if the microstructure is stable it should be run harder to maximize the performance.

Some steels will always be inheritantly brittle at the edge though.

So far carbon PM tool steels are the best candidates for maxing out the edge Performance thanks to the crazy high Rockwell hardnesses that can be achieved in the absence of chromium and relative stable inherit to them.

[Deadboxhero]

While I do not buy into the idea that one steel makes another steel obsolete I do agree that K390 is great stuff and I want more. The Police4 is my only knife in it. I do also have the K2 in 10V which I also like. I want one of these steels in a slightly smaller folder. Bring it on!

Still super excited to score a M4 Shaman!

That's true. I should point out my unique viewpoint. I make knives and have to choose what steels to use. Given the steel options in 2019, I have little room for M4 with my customs.

It is overlapped by other steels that simply do it better but it just hasn't caught up to the mainstream yet because there isn't enough information and models out there yet in these newer steels.

There not new new but it's takes awhile for people to see them in more available knives.

[abbazaba]

Thanks for bringing this up again. I've been lobbying for more K390 and appreciate any thread promoting it. Given the interest, I'm surprised we haven't seen a release since the P4: viewtopic.php?t=77862

My observations with the P4 echo yours... and I've never experienced anything that holds a FINE edge like K390 on the P4. M4 is my benchmark favorite, and have been pleasantly surprised by REX45, but man K390 impresses and I'd be thrilled to see a full Seki run or a few Golden models.

[bearfacedkiller]

A full Seki run in K390 would be great. I am in for a Stretch and a Delica.

Also in for a 10v Military. :)

[ferider]

K390 is pretty tough. Had one of my P4 fall tip down on tiles from 4 feet or so, and the damage to the tip was minimal, easy to fix.

Have used the P4 and the K2 in the kitchen quite a bit. For some reason K390 rusts much easier for me than 10V. Would love some more 10V. How about in the Manix XL ? For that matter, I'll buy an MXL in K390 too :)

[TkoK83Spy]

I've seen a lot of love for K390, but like others have mentioned...hopefully they can expand it's application to more/other models. I know for me personally, I think the Police may be a little too big, and the Urban is too similar in size to many of my favorite smaller folders. Something in the sweet spot between those two models size wise, I wouldn't hesitate to give this steel a try.

[Albatross]

...I'd be thrilled to see a full Seki run or a few Golden models.

I've been wondering if we might actually see this happen. When Sal mentioned the plans for the P4 LW, he mentioned a special color FRN for K390. In my mind, it wouldn't make much sense to do a special color and steel for just one model. That might just open the door for other Seki models, like the Endura, Stretch, and Delica. I'd love to see the Endura and Manix get K390, since they have the best blade shapes and some of the best handles, in my opinion.

[steelcity16]

...I'd be thrilled to see a full Seki run or a few Golden models.

I've been wondering if we might actually see this happen. When Sal mentioned the plans for the P4 LW, he mentioned a special color FRN for K390. In my mind, it wouldn't make much sense to do a special color and steel for just one model. That might just open the door for other Seki models, like the Endura, Stretch, and Delica. I'd love to see the Endura and Manix get K390, since they have the best blade shapes and some of the best handles, in my opinion.

A full Seki run would be nice as an alternate to VG10 for folk like myself who don't care for laminated blades like Hap40, SB, SG, and V-Toku. I'd love to see a Jester in this run (maybe in place of the slower selling Manbug or Meercat?)!

[anagarika]

Shawn,

You did have experience with CS BS in XHP and if I recall correctly, you had quite good impression of high sharpness edge holding it has. I found it to my liking also, opposite to S110V. How different is this P4 in K390 or how much similarities with XHP?

All these talks about it making me wanting one. Alas, currently no budget to get one. A full Seki run is going to be very tempting.

[Baron Mind]

The K is for King

[Deadboxhero]

Shawn,

You did have experience with CS BS in XHP and if I recall correctly, you had quite good impression of high sharpness edge holding it has. I found it to my liking also, opposite to S110V. How different is this P4 in K390 or how much similarities with XHP?

All these talks about it making me wanting one. Alas, currently no budget to get one. A full Seki run is going to be very tempting.

Chris they are not really comparable. I'd say that's a closer match between PSF27, CPM D2 and CPM Cruwear

The K390 has a higher obtainable hardness thanks to the drop in Cr and not being stainless. K390 has a huge volume of very fine Vanadium Carbides which are the hardest next to Niobium and K390 will be more durable at the edge than XHP yet still cut longer. I haven't found a production folder that holds the front end sharpeness as long with this much aggression.

Custom world is a different story.

I'm talking about what you can buy sub $300 production.