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cazten
10-15-2012, 02:36 PM
How do you guys feel about K390 for full sized kitchen knives?

Ive read alot into CPM 10v and K294. Seems very popular as near the best edge and retention you can get, but not very tough. Mostly used in smaller knives as much as I can tell.

K390 is supposed to be a near equivalent but tougher as well. Anyone have experience with it?

HHH Knives
10-15-2012, 02:56 PM
Interesting! I actually have a couple blades in process in K390. I have been doing some testing and am impressed with the initial results. Its its everything they say it is. and with proper heat treat I think it will be a SUPER kitchen knife steel.

Im interested to hear if anyone else have worked with it. used it as a knife, etc.

The specs are stupid good. Im talking CRAZY good.

I was considering a Pass around in K390 the beginning of next year so some guys and gals can test it in some real world use!

jgraeff
10-15-2012, 06:09 PM
I'd love an opportunity to give it a test in a pro kitchen!

RRLOVER
10-15-2012, 08:33 PM
HEY!!!........I thought that stuff was SuperSecret,Nondisclosetionary,SuperDuper wear resistant steel.Did I mention it is a SuperSecret:rofl::rofl::wink:


All joking aside it should be great steel.

keithsaltydog
10-15-2012, 10:15 PM
I noticed that **** has a limited run of M-390 Gyuto wt. custom Tim Johnson handle maple burl,mosaic pins.I have the Spyderco M-390,its edge holding & toughness are deff. above average.

Do not know at this time the deff. between M-390 & K-390,same foundry similar steels.To me 199.00 for a M-390 gyuto,nice looking custom handle is one heck of a good deal.:2cents:

keithsaltydog
10-15-2012, 10:29 PM
Should mention that these blades are 50/50 machine ground.He does use excellent HT at Peter's.

Machine ground is not a problem,wt. freehand skills you can put a polished convex edge on yourself.Tho the 390 steel is tough,it is a little harder to sharpen.It is doable though I'm maybe the only dude wt. a polished convex grind on my Spyderco

keithsaltydog
10-16-2012, 03:39 AM
Sorry so many posts :stinker:I just researched the diff. between K390 and M-390.The big diff. is in the amounts of Carbon & Chrom.

K390 M-390

Carbon-2.45 1.90
Chrom-4.15 20.00
Cobalt- 2.00 -----
Moly- 3.75 1.00
Mangan----- .30
Silicon - .55 .70
Tung. - 1.00 .60
Vanadium-9.00 4.00

Seeing these figures the K390 would be semi- stainless,easier to sharpen.the high carbon,Tung,Vanadium,Moly,cobalt make for sharp edge wt. superior edge holding & toughness.

M-390 Stainless,harder to sharpen,again good edge holding & toughness.


2.45% Carbon is very high carbon steel a plus in kitchen blades= sharp edge ability.Thats more carbon in the Iron than high quality carbon blades.Who is using the K390 steel?

Rottman
10-16-2012, 06:13 AM
I think 4% chrome isn't enough to be called semi stainless and with so much vanadium you'll get plenty of them funny ultra hard vanadium carbides.

Well possible that it doesn't even take a very fine edge.

Marko Tsourkan
10-16-2012, 06:48 AM
Seems like an overkill steel for a kitchen knife, unless made to order for someone who wants a super wear resistant knifes and is willing to invest in equipment maintaining it.

If you think you can get that steel sharp on water stones, think again. You will need diamond plates all the way.

keithsaltydog
10-16-2012, 07:00 AM
Yep,I guess we will have to wait & see.Molybdenum has corrosion resistance as well tho 4.15% Chrom. is not much.Patina's never bother me.

It will be fun to see when someone gets a K390 blade puts it to the stones & starts cutting,I'm interested in it's edge holding ability.

Benuser
10-16-2012, 09:42 AM
Any information about the grain/carbide size?

HHH Knives
10-16-2012, 10:24 AM
3rd gen powder metal. Fine grain. extra fine!

Once you get this steel sharp. Its not going to need re sharpening very often. :)

Benuser
10-16-2012, 10:38 AM
3rd gen powder metal. Fine grain. extra fine!

Once you get this steel sharp. Its not going to need re sharpening very often. :)

Sure, but can you quantify?

keithsaltydog
10-16-2012, 01:23 PM
Seems like an overkill steel for a kitchen knife, unless made to order for someone who wants a super wear resistant knifes and is willing to invest in equipment maintaining it.

If you think you can get that steel sharp on water stones, think again. You will need diamond plates all the way.

Marko wt. my M-390 Spyderco,that I rounded(abusing it wt landscaping work)I did start with diamond plates,tried wt. stones too much work.Since I repair & sharpen Kit. knives I have a couple Atoma's.went like this to get convex edge.Atoma 140-Atoma 600-Bester 1K-Rika 5K-Leather strop

cazten
10-16-2012, 03:02 PM
So wt stones are fine for sharpening then, just not gunna get you anywhere fast for angle changes and grinding.

One of my concerns in wondering just how sharp and edge it will take.

Marko Tsourkan
10-16-2012, 03:08 PM
I guess, I should add that both are great steels, but neither offer a huge advantage over some good steels out there particularly suitable for kitchen knives, like 52100, AEB-L, and some powder stainless steels.

To maintain K390 and M390, one will need diamond plates, as aluminum oxide (most of water-stones are AO) will not suffice. These steels will abrade the AO stone, not the other way around. Steels with vanadium and tungsten in those quantities will definitely require diamond to sharpen.

Taz575
10-16-2012, 08:15 PM
I sharpened up 14 M390 blades recently from no edge (blades ground, edge was completely flat and around .020" thick) to very sharp. I used a belt sander to rough in the bevel, then a Bester 500, Bester 1200, Shapton Pro 2K, Rika 5K, Shobu San and Ozuka Asagi. Stropped on Balsa with boron carbide. Took 20-25 min tops each knife. Took 3 hours for 10 knives after the belt sander to go thru the stone progression listed above. The Shapton GlassStones are supposed to work very well on the steel, too.

Marko Tsourkan
10-16-2012, 09:02 PM
Let me phrase my question differently.

Why get a knife in a steel that is hard to sharpen and that offers maybe 15% improvement on edge retention over conventional steels (well heat treated steels), while it (K390 and M390) cost up to 4X more than conventional steels? Well heat treated A2 will give a comparable wear resistance and can be sharpened on AO stones to a razor sharp.

I don't try to dissuade folks from trying it, just giving you more food for thought, so you can make a better decision.

M

Taz575
10-17-2012, 08:37 AM
Well, speaking to the M390, it wasn't all that much more difficult/time consuming to sharpen than CPM 154.

jgraeff
10-17-2012, 08:56 AM
I agree with Marko from a professional standpoint, I wouldn't want to invest more time to sharpen or more money on diamond plates to get it sharp, although if it really stays that sharp( I mean hair popping sharp) for that long then it could be worth it.

It'd be great for a EDC knife for sure.

Still like to test it out to see what it's all about.

Benuser
10-17-2012, 09:27 AM
Well, speaking to the M390, it wasn't all that much more difficult/time consuming to sharpen than CPM 154.
What kind of edge have you put on it? What angle?

HHH Knives
10-17-2012, 01:11 PM
MANY of the steels used for knives are not for every knife style or application. And thats OK. :D One thing I have learned from you guys is that everyone likes something different in a knife. And individual styles and applications can and do vary greatly between users. This steel may work for some of you and be the best thing you ever used. yet not be perfect for every need or want.

I fully expect it to be harder to sharpen, machine and finish, then some of the steels I have used or tested. That said. Alot of the new PM and powder metals, SWR steels are a PITA to machine and sharpen. The guys who like the traits of these "SUPER" steels and are willing to take the time and effort will most likely LOVE K-390! If you are old school and love the ease of sharpening your edges. and want to sharpen them often. Then this wont be your cup of tea.

My gut feeling and the spec sheet on this stuff will lead me down the road. The cost and time to test and try K-390. If nothing more then to find out for myself. I dont claim to be a expert in steel, or a metallurgist. Alot of the steels mentioned K-390 included are new to me. and Im excited by the potential of these new and impressive metals! And willing to try and test them as I can.

Someone mentioned its cost as a determent. I found it to be closer to 15% more over other PM steel. or other powder metals. That said. What do you get for that price increase?? K-390 has about 2X the carbide forming elements and a couple other elements that will lend themselves to a tougher and more wear resistant quality's then any of the more known and common steels mentioned on this thread. So based on 2X more or the good stuff that should make a great knife steel, at about 15% more per pound.. K-390 could be considered a bargain. :doublethumbsup:



Stay Sharp!
Randy

Benuser
10-17-2012, 01:22 PM
Is the grain / carbide size still a secret, some 15 years after introduction? Do I have to believe Swedish national security is involved?

HHH Knives
10-17-2012, 01:36 PM
Is the grain / carbide size still a secret, some 15 years after introduction? Do I have to believe Swedish national security is involved?

LOL. I dont have a high powered scope to view the grain structure. Heres the specs from Bohler. http://www.bohler-edelstahl.com/files/K390DE.pdf Theres a image of the grain in this steel compared to another similar steel.

keithsaltydog
10-17-2012, 02:44 PM
Thanks for the site Randy,interesting reading about K390.It's applications are for jobs that need toughness in steel.I maybe wrong about it being easier to sharpen than M-390.I just can help thinking how a steel would be wt. that high carbon %.I base it on the large amount of chrom in M390 20% which makes it harder to sharpen,along wt. the Vanadium & Tung. which they both have.

I like the AEB-L steel it is easy to sharpen,not unlike carbon,& because of it's small carbides takes a keen edge.My blue steel carbons hold an edge longer though.

ajhuff
10-17-2012, 03:20 PM
The higher vanadium content dictates a higher carbon content.

Personally I would be attracted to it for the cobalt content.

-AJ

HHH Knives
10-17-2012, 04:46 PM
Interesting. :D I to am intrigued by the Cobalt content! :pirate1:

Cadillac J
10-18-2012, 08:57 AM
As someone who has been sharpening and using the high-alloy super steels in folding knives much more than his kitchen knives lately, I've been thinking about this type of topic.

In the kitchen, I want to get the sharpest possible edge on my blades at the acutest angle that will hold up well...and both the carbon and semi/stainless steels we are used to have been perfectly suited to this task. Edge retention has never been an issue for me to worry about, as all the steels in the knives I have are just fine in this regard (but as a home user, I am not cutting for 8+ hours a day either).

Personally, I have not found 'super steels' to be a problem to sharpen on my regular stones -- it might not go as fast or smooth, but there has never been an issue with getting a really sharp edge. However, I have no need for a steel like this in a kitchen knife because edge retention is not my primary concern...maybe a pro user would have a need for this though.

Although not up my alley, I would love to see this done and hear feedback from people.

ajhuff
10-18-2012, 06:59 PM
I'll be odd man out. I'm only cutting 4-5 hours per shift, and not continuously. I consider sharpening to basically be work. It's not that I hate it. It's kind of therapeutic but not something I look forward to or am eager to do. I want to put my knives away for the day, go home, and tomorrow open my bag up and have a sharp knife. It doesn't have to be hair splitting sharp, just usable sharp. I need to be able to do thin red onions, butterfly chicken, skin teres major, slice tomatoes. As long as it can still do those tasks, I'm good. I probably push my knives to 60% original sharpness before I hit the stones. That can be awhile. I might go weeks. So I'm an edge retention kind of guy. I'd pay extra for that.

-AJ

keithsaltydog
10-18-2012, 08:27 PM
Edge retention is important,as AJ said maybe going at a lesser sharpness before you hit the stones again.I only used carbons at work many Yrs.I actually enjoy sharpening(I have been spoiled wt. carbon).

Thin edges(as long as you do not hit hard objects)paradox actually last longer than wider bevels,that round faster.Creating a back bevel & then blending in a final bevel can extend your edge time during long sessions of cutting.Good qualiy steel wt. superior heat treatment is important.

Taz575
10-19-2012, 03:42 AM
I freehand, I'm guessing around 15 degrees or so. I use pretty much the same angle for most of my kitchen knives, but have never put it on an angle guides to get an exact measurement. I went from an 80 grit belt on a belt sander and went thru a stone progression and ended up with the Ozuka Asagi J Nat as my finisher and then stropped on balsa with Boron Carbide on the balsa. Sticky smooth edge, but it still has some tooth to it. Slices hanging paper towels cleanly.