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What can you say about N690 and M390 steels?

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murtazadalgic

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Hey all,

I'm curious about those steels which is used by many small makers in east europe.
I don't know metallurgy and tried to compare with popular steels like VG10 and Aus-8 but need more info to understand better.

Thank you all.
 

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Barmoley

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Very different steels. M390 is high wear resistance PM stainless steel, lots of carbon, chrome and vanadium. N690 is also stainless, it is basically 440c with some molybdenum and cobalt.
 

murtazadalgic

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Very different steels. M390 is high wear resistance PM stainless steel, lots of carbon, chrome and vanadium. N690 is also stainless, it is basically 440c with some molybdenum and cobalt.

Thank you Barmoley. Do we know any kitchen knife brand uses 440c? I never heard of it, most probably I'm a newbie.
 

Barmoley

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Let's attack this from a different angle. What is it that you are looking for? Steels are one thing knives are totally different. Tell us what you are looking for and we will try to help. Best is to fill out the questioner.
 

Ruso

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I believe Cutco uses 440c. Not saying that thier knives are any good.
M390 is a great steel. I like it in the kitchen knives and in others. I think it’s one of a better all-rounders.
N690 - I did not have good experience with it. But my exposure is rather limited.
Another great and popular steel in Europe is Elmax, somewhat similar to M390.
 

murtazadalgic

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Let's attack this from a different angle. What is it that you are looking for? Steels are one thing knives are totally different. Tell us what you are looking for and we will try to help. Best is to fill out the questioner.
I've seen couple knife makers from my country use these steels that's why I was curious. I don't know their heat treatment though. I filled two times that questionnaire and other members were very helpful. Thanks again.

I believe Cutco uses 440c. Not saying that thier knives are any good.
M390 is a great steel. I like it in the kitchen knives and in others. I think it’s one of a better all-rounders.
N690 - I did not have good experience with it. But my exposure is rather limited.
Another great and popular steel in Europe is Elmax, somewhat similar to M390.
I didn't know Elmax, thank you.

Misono in their 440 series. They do a good job with it. If you require stainless: this one adds some bite, still easy sharpening.
Well on one hand Cutco and on the other Misono 440. It seems heat treating can make you a Brad Pitt or Doug Pitt.
 

Barmoley

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Ah, yes heat treat is very important. If you have some makers in mind and they use both steels just tell them how you will use the knife and ask them what they recommend. Both steels can make great knives. M390 is a lot more wear resistant will be harder to sharpen and much harder to thin. I am assuming good heat treat for both since it doesn’t make much sense to talk about bad heat treat, since any steel can be ruined. pick the maker you like and go from there steel is secondary to the other stuff.
 

martinezz

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Now I'm confused, does the cutco use 440c or 440A? I have read this article where they say it is 440A and in this article on wiki it says the difference in those is quite big. I do not want to buy cutco, but I inherited some and would like to know what steel it really is.
 

Barmoley

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Now I'm confused, does the cutco use 440c or 440A? I have read this article where they say it is 440A and in this article on wiki it says the difference in those is quite big. I do not want to buy cutco, but I inherited some and would like to know what steel it really is.
Cutco website says 440A, but their shape, grind, etc changed over the years so it is possible 440C was used at some point. I'd guess it was 440A all along, just a guess though.
 

-Kiku-

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Bohler M390 is an excellent stainless steel, but for use as kitchen knives? I don't know...

M390 has excellent edge retention, far better than any VG10 can provide.

Lots of vanadium carbides in M390. So if you are going to sharpen it, your only options are to use either CBN or diamond plates.

If you are planning to use M390 as kitchen knives, you will most definitely want to polish it. However, polishing M390 is troublesome due to the significant presence of vanadium carbides. But if you have the patience and skills, M390 will take an excellent polish.
 

Barmoley

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Bohler M390 is an excellent stainless steel, but for use as kitchen knives? I don't know...

M390 has excellent edge retention, far better than any VG10 can provide.

Lots of vanadium carbides in M390. So if you are going to sharpen it, your only options are to use either CBN or diamond plates.

If you are planning to use M390 as kitchen knives, you will most definitely want to polish it. However, polishing M390 is troublesome due to the significant presence of vanadium carbides. But if you have the patience and skills, M390 will take an excellent polish.
I have m390 kitchen knife, it works very well. Doesn't need to be polished, can be sharpened with "regular" stones. Diamonds and CBN work better, but gesshin synthetic stones and king neo ST work fine on it as well. Thinning thick m390 without power tools would be a major pain I suspect.
 

-Kiku-

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To my knowledge, kitchen knives perform better when they're highly polished. Not just the working edge, but the primary and secondary bevels, too. Mirror-finished surface on culinary knives also adds to aesthetics.

When sharpening M390 blade with a coarse whetstone such as 120 or 240 grit size, any type of whetstones will do because at those grit size, you will be sharpening your blade mainly by 'scooping out' chunks of vanadium carbides which are typically around 20 nanometers in size (give or take roughly 50%) embedded in a softer matrix of alloys.

If your M390 knife in question is a typical EDC or bushcraft/hunting knife, then 120/240 grit size will be sufficient. M390 blades. similar to S90V and S110V, perform better when sharpened to low grit size to retain their 'toothiness' for aggressive cutting performance. Kitchen knives such as chef's knife, Nakiri, deba, usuba, etc. on the other hand, require much more refined grinding and polishing work.

As far as I know, there are no mass-production culinary knives made of M390 as of yet. But let's suppose you do happen to have a such knife (maybe you had it custom-made). So as you work your way down to finer grit size, you will have to start abrading those carbides eventually if you want to make further progress at sharpening that blade. FYI, vanadium carbides are approx. 85 HRC on Rockwell C scale, well above the hardness of any traditional Japanese whetstones. So if you attempt to sharpen your M390 blade with a 2000 grit whetstone, the knife will be scraping/sharpening your whetstone instead because those silicon carbides and/or aluminum oxides in whetstones/oilstones are nowhere hard enough to even put a scratch on vanadium carbide.

In general, if you want to use A to sharpen B, then you need to make sure that A has much higher hardness than B, otherwise you're in for an exercise in futility. This is the reason why when it comes to sharpening M390, either cubic boron nitride or diamond plates are your only option. This assertion was made in regard to kitchen knives in general because this thread happens to be located in The Kitchen Knife subforum.
 

Barmoley

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To my knowledge, kitchen knives perform better when they're highly polished. Not just the working edge, but the primary and secondary bevels, too. Mirror-finished surface on culinary knives also adds to aesthetics.
It depends, but in general I would disagree with your statements. Aesthetics are very personal and if you like mirror finish that's fine, I don't. As far as performance goes mirror polish has its issues and kitchen knives definitely don't perform "better" with highly polished edges. Japanese style gyuto knives seem to perform best 2000 - 6000 grid, but most agree that somewhere 3-4k is best for general purpose if we exclude something like soft protein cutting where more polish might be beneficial.

When sharpening M390 blade with a coarse whetstone such as 120 or 240 grit size, any type of whetstones will do because at those grit size, you will be sharpening your blade mainly by 'scooping out' chunks of vanadium carbides which are typically around 20 nanometers in size (give or take roughly 50%) embedded in a softer matrix of alloys.

If your M390 knife in question is a typical EDC or bushcraft/hunting knife, then 120/240 grit size will be sufficient. M390 blades. similar to S90V and S110V, perform better when sharpened to low grit size to retain their 'toothiness' for aggressive cutting performance. Kitchen knives such as chef's knife, Nakiri, deba, usuba, etc. on the other hand, require much more refined grinding and polishing work.

As far as I know, there are no mass-production culinary knives made of M390 as of yet. But let's suppose you do happen to have a such knife (maybe you had it custom-made). So as you work your way down to finer grit size, you will have to start abrading those carbides eventually if you want to make further progress at sharpening that blade. FYI, vanadium carbides are approx. 85 HRC on Rockwell C scale, well above the hardness of any traditional Japanese whetstones. So if you attempt to sharpen your M390 blade with a 2000 grit whetstone, the knife will be scraping/sharpening your whetstone instead because those silicon carbides and/or aluminum oxides in whetstones/oilstones are nowhere hard enough to even put a scratch on vanadium carbide.
Let's assume that if I say I have a kitchen knife in a certain steel then I am telling the truth, otherwise no reasonable discussion can be had. Most of the carbides in m390 are chromium carbides and not harder vanadium carbides. M390 can be sharpened with SiC stones such as 800 grit king neo that I've mentioned, as well as gesshin 1k, 2k, 4k and 6k

In general, if you want to use A to sharpen B, then you need to make sure that A has much higher hardness than B, otherwise you're in for an exercise in futility. This is the reason why when it comes to sharpening M390, either cubic boron nitride or diamond plates are your only option. This assertion was made in regard to kitchen knives in general because this thread happens to be located in The Kitchen Knife subforum.
As mentioned, m390 makes a good kitchen knife and it can be sharpened with quality Japanese style water stones. Everything I've said was related to kitchen knives.
 
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ModRQC

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M390 Properties

Microstructure

The high chromium content in M390 means that less of the high hardness vanadium carbide is present in the steel, and the majority of carbide is the lower hardness chromium carbide. The vanadium does increase the hardness of the chromium carbides, however. You can read more about the interaction between different elements for carbide formation in this article on carbides. Chromium carbides tend to be larger than vanadium carbides in power metallurgy steels which limits toughness, but they are easier to sharpen because they are softer than common sharpening abrasives like aluminum oxide.

@Barmoley makes much more sense with science. Also, the article may illuminate that M390 is no ET steel in knifemaking, although yes, not something inclined to be mass-produced to an extent that would match Shun's VG-Max........
 

M1k3

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Mirror finish to sticky and "LOOK AT MY SCRATCHES" for a restaurant with any kind of busy pace.
 
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