Carbon steel folders

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mercutio99x

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Apr 27, 2022
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How come there are so few modern folders in non stainless steels? Specifically things like K390 and M4. I can't be the only one that really doesn't prioritize corrosion resistance, and K390 seems like its fantastic as a knife steel if corrosion isn't a big concern. I would have thought there would be at least more offerings than the handful of Spyderco models available. Any insight into why that is?

This may force me into getting my first Spydie - generally don't like the scales or the look of the blades with the round hole, but that Delica in K390 might be the one...
 
ZT0456 released a M4 edition
Medford has some 3V models
There's probable several reasons why makers don't change steel options very much. Maybe it's the price of material, tooling costs, reliability issues, difficulty working with different steels. I think corrosion is a big concern for most people, especially in the hidden areas of a knife. People, like me are lazy and forgetful to either take a knife apart or flush a knife to keep rust from forming. It's easier to use one and not have to worry about cleaning it.
 
I love a carbon steel folder. Most of my traditionals are 1095, and I’ve kind of gone that same path with my moderns as much as possible.

In addition to the Delica in K390 (which I’ve been considering as well), there is an M4 version out there as well, along with a K390 dragonfly 2. You may still be able to find the M4 PM2 and M4 Manix 2 LW, two of my favorite knives. And if you don’t mind putting in a little elbow grease, there are a couple of M4 Benchmades that are (or were) available, specifically the Bugout and the Osborne. Unfortunately BM seems to coat all their blades like this, so I’ve sanded mine back to plain, so I can enjoy that sweet patina that steel gets!

Fwiw, Cruwear is another high carbon steel I like a lot, but its tendency to want to take a patina is much less than M4. Also fairly widely available in Spydercos, as well as a few Benchmades. Also may or may not need a little elbow grease to remove the blade coating.
 
Benchmade offers the Adamas and Mini Adamas in Cruwear, the Bailout in 3V and M4, the Presidio in M4, and the Freek in M4, the Redoubt in CPM-D2, and the Claymore in CPM-D2, all as regular production knives. There are tool steel exclusive variants of other models too like the 940 and Bugout. That's a lot of examples. I also enjoy these high alloy steels.

The upcoming Immunity is also in M4.
 
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mercutio99x said:

Carbon steel folders​

How come there are so few modern folders in non stainless steels? Specifically things like K390 and M4. I can't be the only one that really doesn't prioritize corrosion resistance, and K390 seems like its fantastic as a knife steel if corrosion isn't a big concern. I would have thought there would be at least more offerings than the handful of Spyderco models available. Any insight into why that is?

This may force me into getting my first Spydie - generally don't like the scales or the look of the blades with the round hole, but that Delica in K390 might be the one...
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Just to be clear, K390 and M4 are not "carbon steel". They are non-stainless high alloy steels. Carbon steels are the 1000 series. 1095 and such.

My insight as to why there are so few such pocket knives is that pockets tend to be damp and sweaty (read "salty"). That's not a friendly environment for non-stainless alloys.
 
What carbon steels vie for "King of the Hill"? Back when I carried HC folders, I shopped by the knife's brand name and didn't know what kind of steel I was buying.
 
knarfeng said:
My insight as to why there are so few such pocket knives is that pockets tend to be damp and sweaty (read "salty"). That's not a friendly environment for non-stainless alloys.
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I certainly could not agree with that more. Growing up as an overactive child in South Texas I hiked, camped, fished, swam in the creeks and spent every moment I could outside even in the nasty heat.

Then I went into the trades and continued to spend my days outside sweating my rear off. I got tired of doing some kind of oiling and rust prevention every day in the summers. My friends could not believe that I sweated through my jeans and belt nearly every day in the heat when at work.

I hated the fact that if I didn't use my knife in my pocket for a couple of days that it could be covered with rust and the salt I expired when sweating when I pulled it out to use it. So you can bet the farm on the fact that when there were finally good enough stainless steels to make a work knife I switched immediately.
 
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Thanks everyone for the examples of non stainless options. Still far fewer options compared to the stainless options, and especially the K390 which from the information I gathered was performing better than M4. I had considered some of the M4 Spydercos or something like the benchmade mini freek in m4 I see listed as a pre order (I'm not sure I'm able to justify buying that anytime soon though). It was just surprising to me that there wasn't the availability. It's also a little interesting that it seems mainly US based companies are offering it.

I think stuff like Magnacut is kind of a marvel in how it does everything pretty darn well. I've never had any issues with rust unless it was my own fault, and therefore that aspect wasn't really the biggest selling point for me.

knarfeng said:
Just to be clear, K390 and M4 are not "carbon steel". They are non-stainless high alloy steels. Carbon steels are the 1000 series. 1095 and such.

My insight as to why there are so few such pocket knives is that pockets tend to be damp and sweaty (read "salty"). That's not a friendly environment for non-stainless alloys.
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I appreciate the clarification. I should have said non stainless, I suppose.

I'm not sure how well the argument about pockets being a hostile environment holds up (at least for me). I don't doubt that there are problems there, but weren't most traditional folders non-stainless for a long time and worked ok? Or were there corrosion issues I'm not aware of...?
 
knarfeng said:
Just to be clear, K390 and M4 are not "carbon steel". They are non-stainless high alloy steels. Carbon steels are the 1000 series. 1095 and such.

My insight as to why there are so few such pocket knives is that pockets tend to be damp and sweaty (read "salty"). That's not a friendly environment for non-stainless alloys.
Click to expand...
My understanding is that M4 is carbon steel. Larrin knows better than either of us. Anyone have a link to his definition?

If we assume that M4 is carbon steel, Benchmade and Spyderco have both made many knives in carbon steel. For example the GB2 in my pocket right now. Or the Contego and Bailout at home in my knife drawer.
 
I carried Case folders in high carbon steel, probably 1095, for a lot of years without any rust problem. Same for my hunting buddy who had a Schrade LB7. At the moment the only carbon steel folder I have is an Opinel,which gets wiped dry after use but that's all. It has a lovely patina. FWIW, tool steels like M4 are pretty rust resistant; my GB2 has picked up only a few tiny blemishes after significant use over the last couple of years and no babying.
 
DMG said:
My understanding is that M4 is carbon steel. Larrin knows better than either of us. Anyone have a link to his definition?

If we assume that M4 is carbon steel, Benchmade and Spyderco have both made many knives in carbon steel. For example the GB2 in my pocket right now. Or the Contego and Bailout at home in my knife drawer.
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Carbon steel simply refers to steel which has mostly carbon added to it and little else. Carbon steel tends to be pretty crappy for knives due to very low edge retention and corrosion resistance. The steels this thread is about have more than carbon added and are therefore referred to as high alloy tool steels.

Thorgrim said:
What carbon steels vie for "King of the Hill"? Back when I carried HC folders, I shopped by the knife's brand name and didn't know what kind of steel I was buying.
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If by carbon steel you mean high alloy tool steels, the current high performers are, from highest toughness to highest edge retention: Z-Tuff, 3V, Cruwear, Vanadis, 10V, Z-Max, 15V, Maxamet, and Rex 121.

M4 and 4V are now "obsolete" thanks to Magnacut.
 
I had K390 Endura and sold it.

Despite using it to cut meat, fruits, veggies and so on to give it patina - small spots of rust would still show up.
Constant oiling was a chore, having something oily or greasy in the pocket also kinda sucked, and hot summer, humidity and sweat were just doing their thing.

I sold it once action started getting gritty as it was an uphill battle. It also took away a lot of joy from using it.

Steel did perform though. I loved the knife but just couldn't get over that.

Got Recon1 later and never looked back. Arguably, K390 is better steel than S35VN. But with S35VN there's no hassle with patina, rust, oiling or corrosion around the pivot. Just use and resharpen when needed.
 
"Modern" makers need to use "modern" materials. Carbon steel ain't it.

If you like carbon steel, explore the world of traditionals. They were the bomb when people actually depended on knives to make a living. They place function over form, unlike today's knives.

The Svord peasant knife will give you a lifetime of service and is easy to maintain and use.
IMG-2022-02-26-08-25-12-146-2.jpg
 
Benchmade super Freek comes with M4 if you like the design and are willing to spill the cash!
*I believe there's a mini version with M4, as well? not sure if it's standard production though
 
DMG said:
My understanding is that M4 is carbon steel. Larrin knows better than either of us. Anyone have a link to his definition?
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AISI Designation system :: Total Materia Article

www.totalmateria.com www.totalmateria.com

DESIGNATION OF CARBON STEELS AISI/SAE​

DEFINITION. Steel is considered to be carbon steel when no minimum content is specified or required for aluminum, chromium, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium, or zirconium, or any other element added to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.40%; or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60.

www.azom.com

M4 Molybdenum (UNS T11304) High-Speed Tool Steel

High-speed tool steels are broadly classified into molybdenum high-speed steels and tungsten high-speed steels. The molybdenum high-speed steels are also referred to as Group M steels.
www.azom.com www.azom.com
1680145228837.png

I'm not a metallurgist, but I am a materials engineer.
 
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