Cpm s90v review for kitchen use

[Taz575]

Wow! I may have to get some of those sheets one of these days!

 

[insidiousaudio]

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You making these?

 

[blokey]

You making these?

@Andrei makes these

 

[farid]

Personal experience has taught me CPM-s90v (was CPM-420v) is one of the best steels there is, expensive and I still use it, the best hardness for this steel is actualy around 60RC as it will give a certain degree of toughness as well, over this RC well it depends on the grind 'geometry, edge geometry' long subject to demo and talk about.
After this steel is heat-treated when you come to grind to finished size, if a maker out there is using a fixture to grind then no problem as long as you are using 3M 784F or 984F cubitron belts, if you are grinding free hand then it's much more challenging.
It's amazing stuff with 9% Vanadium carbides.
Farid Mehr
knife maker

 

[insidiousaudio]

Personal experience has taught me CPM-s90v (was CPM-420v) is one of the best steels there is, expensive and I still use it, the best hardness for this steel is actualy around 60RC as it will give a certain degree of toughness as well, over this RC well it depends on the grind 'geometry, edge geometry' long subject to demo and talk about.
After this steel is heat-treated when you come to grind to finished size, if a maker out there is using a fixture to grind then no problem as long as you are using 3M 784F or 984F cubitron belts, if you are grinding free hand then it's much more challenging.
It's amazing stuff with 9% Vanadium carbides.
Farid Mehr
knife maker

Is it about as tuff as vg10 in that hrc?

 

[Blank Blades.]

Is it about as tuff as vg10 in that hrc?

Really s90v and vg10 are pretty similar as far as toughness in general.

 

[farid]

Is it about as tuff as vg10 in that hrc?

VG10 in my opinion should not be compared with CPM-s90v, one is a pretty low alloy steel the other is highly alloyed, if I was to answer your question I would first say any PM powder steel would be tougher because of the micro structure of the matrix and they are very pure and clean steels, I would say my money would be on s90v.
I have actualy put movies on the internet showing the destruction of M2 HSS blades at 65rc, and T1 HSS 65rc, they actualy bend quite a bit before shattering, some R&D would have to be carried out on VG10 heat-treating to ascertain how good it can be, I don't use VG10 but I have had very high end kitchen knives Damascus san mai with this stuff in the core, out of 23 knives I owned 'none' would hold an edge for any length of time, I sold them all. One of my knives I make and use myself in the kitchen is a chopper made from M35 HSS 64rc, I once tested the edge on thick cardboard and it cut a whole heap of cardboard for 45 minutes and then I cut wood with it, after all this it shaved the hair off my arm, this movie was once upon a time on YT, I still have it. M35 is similar to M2 but it has 5% cobalt carbides.
Farid Mehr
knife maker

 

[insidiousaudio]

VG10 in my opinion should not be compared with CPM-s90v, one is a pretty low alloy steel the other is highly alloyed, if I was to answer your question I would first say any PM powder steel would be tougher because of the micro structure of the matrix and they are very pure and clean steels, I would say my money would be on s90v.
I have actualy put movies on the internet showing the destruction of M2 HSS blades at 65rc, and T1 HSS 65rc, they actualy bend quite a bit before shattering, some R&D would have to be carried out on VG10 heat-treating to ascertain how good it can be, I don't use VG10 but I have had very high end kitchen knives Damascus san mai with this stuff in the core, out of 23 knives I owned 'none' would hold an edge for any length of time, I sold them all. One of my knives I make and use myself in the kitchen is a chopper made from M35 HSS 64rc, I once tested the edge on thick cardboard and it cut a whole heap of cardboard for 45 minutes and then I cut wood with it, after all this it shaved the hair off my arm, this movie was once upon a time on YT, I still have it. M35 is similar to M2 but it has 5% cobalt carbides.
Farid Mehr
knife maker

Yea same reason I got the magna cut it was way tougher and had better edge retention.
I'm chasing sharpness and edge retention without having to worry about chipping when chopping. That brings me to k390 and vg10. The thing that steers me away is they are prone to rusting alot faster than the vg10 or magna cut

 

[jedy617]

I don't know, VG10 is probably not what you are going to be looking for edge retention or toughness wise. This is not a perfect guide, but I recommend looking at this to make some relative comparisons: https://knifesteelnerds.com/2021/10...ness-edge-retention-and-corrosion-resistance/

 

[insidiousaudio]

I don't know, VG10 is probably not what you are going to be looking for edge retention or toughness wise. This is not a perfect guide, but I recommend looking at this to make some relative comparisons: https://knifesteelnerds.com/2021/10...ness-edge-retention-and-corrosion-resistance/

I own a vg 10 knife that people said was chippy and it's not. I also own a zdp 189 I wouldn't chop chop cut with and a magnacut that's really tough.
With the vg10 being in the 4 range I'd say that's the lowest I'd go

 

[Taz575]

Some VG 10 is chippy and gunny feeling, others are much nicer, so a lot depends on the heat treat, too!

 

[insidiousaudio]

Some VG 10 is chippy and gunny feeling, others are much nicer, so a lot depends on the heat treat, too!

That's how my miyabi felt. It made my stomach stomach turn A lil. Lol

 

[Blank Blades.]

VG10 in my opinion should not be compared with CPM-s90v, one is a pretty low alloy steel the other is highly alloyed, if I was to answer your question I would first say any PM powder steel would be tougher because of the micro structure of the matrix and they are very pure and clean steels, I would say my money would be on s90v.
I have actualy put movies on the internet showing the destruction of M2 HSS blades at 65rc, and T1 HSS 65rc, they actualy bend quite a bit before shattering, some R&D would have to be carried out on VG10 heat-treating to ascertain how good it can be, I don't use VG10 but I have had very high end kitchen knives Damascus san mai with this stuff in the core, out of 23 knives I owned 'none' would hold an edge for any length of time, I sold them all. One of my knives I make and use myself in the kitchen is a chopper made from M35 HSS 64rc, I once tested the edge on thick cardboard and it cut a whole heap of cardboard for 45 minutes and then I cut wood with it, after all this it shaved the hair off my arm, this movie was once upon a time on YT, I still have it. M35 is similar to M2 but it has 5% cobalt carbides.
Farid Mehr
knife maker

I wouldn't call vg-10 low alloyed. Even comparatively. It just isn't a high vanadium steel, super high wear resistance steel.

It does have a good bit of alloying still.

 

[jedy617]

I own a vg 10 knife that people said was chippy and it's not. I also own a zdp 189 I wouldn't chop chop cut with and a magnacut that's really tough.
With the vg10 being in the 4 range I'd say that's the lowest I'd go

I mean it's probably thicker behind the edge then. It does not have the best edge stability. I also have not chipped ZDP either. But they still aren't tough steels. You have a lot to learn my friend

 

[ptolemy]

I would be curious to know how does k390 compare to s90v. Seems like k390 has enough toughness to be a monosteel blade, where as s90v likely better in a san mai treatment

 

[jedy617]

I would be curious to know how does k390 compare to s90v. Seems like k390 has enough toughness to be a monosteel blade, where as s90v likely better in a san mai treatment

What does san mai have anything to do with toughness? Edge stability is what's important, cladding has nothing to do with that. Regardless, used s90v monosteel in kitchen and edc appliances for years and it's great, one of my favorite stainless. Definitely tougher than hitachi stuff, it's around sg2 but much higher edge retention of course. K390 is tougher, less edge retention.

 

[insidiousaudio]

I mean it's probably thicker behind the edge then. It does not have the best edge stability. I also have not chipped ZDP either. But they still aren't tough steels. You have a lot to learn my friend

I'm learning. Show me they ways. Lol
I've tested all the knives all at around 14 degrees. I'm kinda at this point chasing sharpness and edge retention. And from what I come to the conclusion to hold an edge that won't fold you want toughness and to hold an edge for retention you want a harder finener grain structure that has to be sharpened better meaning I'm doing 320 800 2000 5000 12000 then the finer grains pull away and stay sharper

 

[jedy617]

I wouldn't recommend past like 3000 grit for very high alloyed steels. I would also do a lot of reading on here on who can make you some nice knives instead of messaging the first ones you see that have that steel in them. If you didn't know, geometry and edge angle matter more than steel choice for edge retention first and foremost..

There are quite a few of great, active makers on here who use steels you are considering, I would slow down and do a little reading and check out some reviews

 

[Blank Blades.]

You aren't completely wrong or anything. But if you want a fuller picture.

Harder, generally means stronger for materials, particularly steel. Though higher hardness means reduced toughness, and that's also a generalization, but for this going to deep won't be a benefit.

Edge stability is a term to describe how well the edge avoids deformation or chipping. Generally higher hardness means better edge stability. Up until you get to the point where the edge is chipping, and that is the dulling mechanism.

Then you have wear resistance. For steels that is controlled by two things. Hardness, and the carbides in the steel. Higher hardness, means more wear resistant. Higher volume of carbides means higher wear resistance. But when you get into carbides, there are a lot of different elements that can form them. And some of them are harder than others.

An important thing about carbides, is they are very hard, and them being in the steel does reduce toughness. The type doesn't matter the toughness controlled by the volume of them. So you want the hardest carbides you can get because whether it's just simple iron carbides (cementite, which is as soft as it gets for these), or vanadium, niobium, or any other mc type carbide (the hardest ones). The toughness is going to be reduced the same amount.

A side note is carbide size also matter for toughness, which is where powder metallurgy steels like s90v come it. It allows there to be a higher volume of carbide, while keeping them small. I don't want to go into why that happens here, but just know that that's what happens.

So we have hardness, carbide volume, and the toughness that comes from the result of those two things. Along with the wear resistance. And that is what we are looking at when with these knives and how they interact.

To get into sharpening. Generally speaking. To avoid chipping. Finer is more ideal, because with a coarse edge the deeper scratches actually act as tiny stress risers to allow small cracks to start forming. So you will get better edge stability with a finer edge.

Though a coarse edge is better for slicing edge retention.

So anyway there is a lot that goes into all of this.

 

[MSicardCutlery]

Seems like k390 has enough toughness to be a monosteel blade, where as s90v likely better in a san mai treatment

A distinction needs to be made between blade toughness, and edge toughness. San-mai construction can make for a stronger blade, though outside of the realm of swords and wood chopping knives it doesn't really matter beyond aesthetics and thinning. It will not however, make for a more chip resistant edge.

If my infirm grasp of engineering is right, in order for that to be possible, the core could protrude beyond the cladding no more than an amount equal to or less than its thickness, with a sharpening angle no more acute than 90 degrees. San-mai may limit the size of chips you get, but whether it's 5mm tall or 15, really the knife is in need of serious machine repair beyond the abilities of the average cook.

 

[jedy617]

I wanted to say that as well, we are not taking about swords where there is an impact on areas outside the edge and at much greater force. Idk where the idea that San mai has anything to do with edge properties has come from

 

[MSicardCutlery]

I wanted to say that as well, we are not taking about swords where there is an impact on areas outside the edge and at much greater force. Idk where the idea that San mai has anything to do with edge properties has come from

Unfortunately, I think it's just an erroneous carry over by people, perhaps even the smiths themselves who didn't understand the dynamics of it. Sadly, even Carter promulgates this idea in one of his videos.

 

[jedy617]

Unfortunately, I think it's just an erroneous carry over by people, perhaps even the smiths themselves who didn't understand the dynamics of it. Sadly, even Carter promulgates this idea in one of his videos.

It's hard, I love Carter's knives and think he's a cool dude, but it's so strange seeing those high end makers propagating just straight up myths and false statements and then they are believed because of their standing.

Thankfully I think this is becoming much less the case lately especially with newer younger makers and stuff like knife steel science by larrin, etc.

 

[Blank Blades.]

But muh mysticism.

 

[farid]

Yea same reason I got the magna cut it was way tougher and had better edge retention.
I'm chasing sharpness and edge retention without having to worry about chipping when chopping. That brings me to k390 and vg10. The thing that steers me away is they are prone to rusting alot faster than the vg10 or magna cut

Yes I understand, there are limitations on tools which rust and also tools which do not rust, they have limitations too.

 

[MSicardCutlery]

Thankfully I think this is becoming much less the case lately especially with newer younger makers and stuff like knife steel science by larrin, etc.

Very much so. The pre KNS is the bladesmith's dark ages by comparison to what it is now.

*Cough*....3x + normalizing cycles, *cough* vanadium enhanced wear resistance in W2, *cough* the superior corrosion resistance of 52100 due to the chrome, grain size fetishization.....and the list goes on.

 

[jedy617]

But muh mysticism.

That is why I collect honyaki. Me likey samurai swords. Hamon gives da soft spine for when I am doing battle

 

[farid]

I would be curious to know how does k390 compare to s90v. Seems like k390 has enough toughness to be a monosteel blade, where as s90v likely better in a san mai treatment

Can't compare I would say, first of all we all need to understand one thing here about steels, there are carbon steels out there, there are tool steels out there, there are tooling steels as well, then there are High Speed Steels, HSS high speed steels are steels designed to CUT 'OTHER STEELS' they are designed to have high hardness+ some have high 'Red Hardness' which means when you are cutting something it does not loose it's edge when it is heated up during the cut, which means they have Cobalt added, Cobalt also have been known to add toughness.
s90v is a high carbide stainless, K390 is a High Speed Steel with the added 1% tungsten and 2% Cobalt, s90v is not on the same level for a knife blade (when it comes to performance as well as toughness)
Farid Mehr
knife maker

 

[jedy617]

Can't compare I would say, first of all we all need to understand one thing here about steels, there are carbon steels out there, there are tool steels out there, there are tooling steels as well, then there are High Speed Steels, HSS high speed steels are steels designed to CUT 'OTHER STEELS' they are designed to have high hardness+ some have high 'Red Hardness' which means when you are cutting something it does not loose it's edge when it is heated up during the cut, which means they have Cobalt added, Cobalt also have been known to add toughness.
s90v is a high carbide stainless, K390 is a High Speed Steel with the added 1% tungsten and 2% Cobalt, s90v is not on the same level for a knife blade (when it comes to performance as well as toughness)
Farid Mehr
knife maker

Define performance? At least in CATRA testing s90v does in fact beat k390 and obviously is much more stainless. For most people I think it's a better choice.

 

[farid]

Define performance? At least in CATRA testing s90v does in fact beat k390 and obviously is much more stainless. For most people I think it's a better choice.

The best way I can answer this question is in my own way.
Yes you are right for 'most people' s90v is a better choice because they do not want to bother taking care of a tool which is not stainless, but, I stand by what I have said about K390 steel, provided the heat-treating is done well, hardening as well as the tempering cycles (all can be proprietary info to a maker too because of the R&D they have put in), the grind geometry is good, edge geometry is good, provided the tool is a well designed tool I am willing to one day do a comparison testing on both steels, I just have to find the time to do this. As far as performance goes (edge holding) as well as toughness my money is on K390. But that's only what I'm saying.
Farid Mehr
knife maker