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"Stainless" vs "Carbon" steel

Discussion in 'Non-Firearm Weapons' started by JohnKSa, Jan 10, 2018.

  1. JohnKSa

    JohnKSa Moderator Staff Member

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    I don't really get all the hullaballoo about knives that are hard to sharpen. If I can pay the premium for a really wear-resistant blade, why wouldn't I be able to afford a pocket diamond sharpener to carry in the field? I used to have a set (coarse and fine) that were thin enough to fit in my wallet and I think I paid less than $20 for both of them combined.

    But that's just me. I'm sure that it is a major issue for some people and that doesn't bother me at all. If someone wants carbon steel knives so that they can sharpen them easily without using diamond or ceramic stones then that's fine. What I just don't understand is the repeated assertions that carbon steel takes a better edge or is tougher than any stainless steel. I don't understand it because the composition charts seem to indicate otherwise. I don't understand it because I've been trying to find quantitative data to do the comparisons that would prove or disprove the statements and I can't--which makes me wonder where everyone who is sure that the statements are true is getting the data to confirm them.

    I just wish there was some way to know for certain (without doing extensive destructive testing personally) and to be able to demonstrate to others what steels are actually stronger/tougher/more wear resistant/more corrosion resistant. I don't think it's too much to ask for knife makers to provide quantitative information on the topic.
    Sure, I mentioned in my first post that there are clearly some advantages to carbon steel. I didn't mention aesthetics, because I would think that for the most part (barring those who like patina on their blades) the aesthetic advantage, when it comes to knives, would probably go to stainless steel.
     
  2. Mizar

    Mizar Member

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    I don't think that anyone would argue that powdered stainless steels outperform pretty much everything else, especially plain carbon steels, but for me the details are also important - outperforming yes, but to what degree? Furthermore, steel performance is in direct correlation with heat treating, blade geometry, cutting edge angle and geometry, how exactly it was sharpened... Many times a knife made from a lesser steel will show much better results compared to another knife, made from some top of the line "super steel", just because the first maker is better at heat treating. And we should specify what exactly do we understand with the term "carbon steel" - the strict AISI definition, or the more broader one which includes and the alloy non-stainless steels. For example: BS1407, aka "Silver steel" (1.2210, 115CrV3) - where does it stands? For me it's a carbon steel, but for somebody else it is not. We should consider that with some of the comments - what exact alloy one is referring to when saying "Carbon blade"?

    A guy (he goes by the nick-name Bradley) from a local knife forum made quite an extensive test some 6 years ago which included many different blades, all sharpened by him, cutting some heavy duty cardboard. The top results, without claiming anything in particular, but only showing some interesting "anomalies", are as follows:

    1. Jukka Hankala Tommy, RWL 34 - 3500 cuts
    2. A knife from local knife maker (Silverman), CPM 3V - 3000 cuts
    3. Spyderco Mule Team 3, CPM S90V - 2600 cuts
    4. Jukka Hankala Tommy, Silver steel - 2500 cuts
    5. Pekka Tuominen blade, Silver steel - 2200 cuts
    6. The same local knife maker as #2, CPM 3V - 2200 cuts
    7. Pekka Tuominen blade, 52100 - 2000 cuts
    8. Buck Ergo Hunter, CPM S30V - 1800 cuts

    So, the interesting part (at least for me) is that although powdered stainless shows better performance overall the lowly non-stainless alloy steels which I call "Carbon steels", in the hands of a good knife-maker, do perform very, very well also. I understand that such tests are showing only a small part of the overall performance and do leave many questions unanswered, but it's nevertheless an interesting comparison.

    One last example: I introduced myself to the D2 steel only about an year ago. The main thing that stopped me for so long was all the comments about it not being able to hold a fine 20 degree edge and that it should be sharpened with coarser grits for max results. But I needed a cheap and well performing folder anyway so I finally settled for this:
    http://www.manlyusa.com/product/manly-peak-black-d2
    It's a knife from a local, Bulgarian company and the fact that a friend of mine (he is also a knife maker) works there and that they have good track record with D2 heat treating settled it for me. BTW, the steel is not exactly the AISI D2, but the German DIN analog - 1.2379. Yes, I followed the sharpening instructions about it. So, I was cutting cardboard like crazy, pretty much enjoying it's performance until one day I cut some rope pipe tobacco with it. After only about 15-20 cuts that knife started to get dull. And I was like "WTH!?! My Carbon Opinel #9 performs not much different!". And that cheap Opinel would not cut even one tenth of the cardboard I tested my new Manly folder with. So, all of my rambling aside, I meant to say that with steels not everything is black and white - there are variables, nuances, we should also take into consideration.
     
  3. JohnKSa

    JohnKSa Moderator Staff Member

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    That's part of what makes this such an interesting topic to me. Even on this thread people are arguing that plain carbon steel will outperform the stainless super steels--here are 4 examples.
    Right, that's a big part of this topic and why I wonder if it even makes sense to keep talking about carbon steel vs stainless steel like there's a practical difference between the carbon content that gives the carbon steels hardness advantage. As Cowhide Cliff states, "...they say "no I've got to have a 'high' carbon blade". Well what they don't realize is my stainless knives have much more carbon than the ones they are referring too."

    I find the cutting tests interesting and they do indicate that it's possible to make a knife that performs very well out of a wide variety of steel, not just the "super steels". The problem is that those test results incorporate a lot of variables that have very little to do with the steel and a lot to do with the knives and even with the person using/sharpening the knives. This is why I think that repeatable test data directly from the manufacturers based on testing the steel itself would be invaluable. Then you don't have to guess how much of the results from a cutting test are due to the design of the knife or the skill of the person who sharpened it or the person who is wielding it.

    It would also be very practically useful because it would help users make informed decisions about how aggressive a bevel angle they want to use when they sharpen the blade based on the properties of the steel and on the intended use of the knife.
     
    Last edited: Jan 13, 2018
  4. Mizar

    Mizar Member

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    I understand your concerns because the same issue frustrates me a lot when looking for information regarding some new to me steel. In general, reviews are not really helpful either - too much personal opinions, different experience, different grading, different understanding for what is more important and what is not in a blade (steels). I tend to believe by the way, that the knife maker's ability to work with some steel - heat treating, blade shaping and etc. is more important than the steel itself. But the different steel comparison charts that float around the Net should give one a good start regarding different properties of the steel alloys of interest. After that it's really about personal experience and deciding if you like it or not for your intended use. I'm really sorry that I can't be of real help about the subject - it would be great if someone with a Metallurgy degree and real practical experience joins the discussion.

    P.M. Seems that the "general wisdom" on the subject is that high carbide content steels (including CPM ones), while having a superb wear resistance, do not perform well on impact. So, maybe there is some truth in saying that quality Carbon blades will outperform "Super stainless" in some instances.
     
    Last edited: Jan 13, 2018
  5. readyeddy

    readyeddy Member

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    So if a powdered stainless steel is superior to say 5160, then does that mean stainless steel can be used to make a functional sword for battle and outperform a high carbon steel sword?
     
  6. Mizar

    Mizar Member

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  7. JohnKSa

    JohnKSa Moderator Staff Member

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    The operative word in your statement is "if". As written, your statement is true.

    What I'm trying to find is some data that tells us whether or not your "if" is true. But yes, IF there are powdered stainless steels that are tougher/stronger/more fracture resistant than typical non-stainless carbon steels then it would also likely be true that they would make better swords.
     
  8. Cowhide Cliff

    Cowhide Cliff Member

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    They are not more fracture, chip resistant unless you draw temp them back. The biggest thing I see is IMO most makers and heat treaters of the modern stainless steels run it too hard. XHP will get to 64rc. In my testing it works best in cutlery down around 60 or even softer but you have to draw temp at over 500 to get it that soft. Many of the old favorite carbon steels won't even get that hard before draw temp.

    Same as the big deal so many make about cryo treating them. Some retained austenite is not a bad thing in a knife blade.

    I have a knife in my hunting pack that I made as a test knife a few years back and pretty much abused it deer hunting one year. The blade is CTS-XHP I ground the blade thinner than I normally would for a hunting knife and pounded it through pelvic bones busted rib cages and actually chopped the ribs off of a couple carcasses. I wrinkled the edge of that blade but it's never been resharpened other than hit it on some ceramic crock sticks and the knife will still shave hair.

    There is that happy medium between edge holding and toughness from chipping and breaking. If it wont bend some it's too hard.
     
  9. JohnKSa

    JohnKSa Moderator Staff Member

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    I would assume that any performance parameters would have to be provided with various hardness levels. As you say, you can harden just about any steel to the point of being uselessly brittle.
     
  10. Madcap_Magician

    Madcap_Magician Member

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  11. JohnKSa

    JohnKSa Moderator Staff Member

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    Very interesting--thanks very much for the link! It's too bad there's not more of this kind of data available.
     
  12. Cowhide Cliff

    Cowhide Cliff Member

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    It's still just a bunch of the same babble that has been going on forever. Comparing D2 of unknown sources, just like 440C, it's not all created equal. There was a time CPM154 was horrible when Crucible went through it's problems. Did you know Crucible made a run of CPM-D2??? Yes they did, I still have three or four bars of it under my bench for those D2 lover collectors wanting it. Carpenter 40CP was only made in like one run, was an awesome steel but once people realized it was essentially a powdered 440C that was it's doom because 440C has gotten the rap of being old outdated even though all of the modern super steels are variations that start there. One of those being XHP which works and performed so great it became an immediate favorite drowning out the other variations Carpenter introduced and many of us experimented with along the same time. The test would have to be an old one from 10 years or more and I wonder why they choose the 40CP over XHP.

    I actually wish they had continued making 40CP because it was easier to work with and polish than XHP for a show quality knife and performed very well. In ways and some applications I think better than XHP because it would be easier to sharpen if and when it does need it. Not that XHP needs it often.

    Nothing wrong with some of the Sanvik steels but as a knifemaker I just never liked the way it worked and felt as well as especially the new Carpenter steels which I feel are the best and cleanest steels available today. You really get a feel of how clean a steel is when you sand to 2000 grit and buff for that mirror finish you can go to the point of seeing the grain structure of the steel. The grain in Carpenter powdered metals is so fine and even.
     
  13. Madcap_Magician

    Madcap_Magician Member

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    I'm seeing a big resurgence in AEB-L that had me scratching my head for a while. I mean, that's an ancient stainless steel that's been used for razor blades since forever.

    But a lot of experimenters are telling me it can be heat treated tough at relatively high hardness with a fine grain structure. The Nitro-V alloy adds a dash of nitrogen and vanadium to the otherwise simple stainless AEB-L. I know one guy is making machetes out of it to rave reviews.
     
  14. Slamfire

    Slamfire Member

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    I love the way plain carbon steel knives cut, how easily they sharpen,

    AvbHWCE.jpg

    I just freak out about rust.

    The top one is stainless, takes a great edge, cuts well, hard to rust. In the kitchen, that is good enough for me.

    vKFjF3Y.jpg
     
  15. JShirley

    JShirley Administrator Staff Member

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    Since there are plenty of folks who have no idea that "powdered stainless steels" exist, I'd take that bet. Your statement as written, though, appears to be incorrect, or at least incomplete. The 5160 mentioned a few posts later won't make a better small knife than most modern stainless knife steels, but can make a better large blade than all but a few steels. As blade length increases, leverage increases, putting increasing amounts of pressure on the blade. A RC that makes a terrific 4" bladed knife will typically be inappropriate for a 10" bladed hard-use knife.

    I recently bought a very large knife from Spyderco. I think it'll work fine as a "fighter", but I'm sure its hard modern stainless steel blade wouldn't hold up to rough outdoor use as well as one of my 5160 kukris banged out over a charcoal fire in a 3rd world country, and valued at less than 1/3 of the Spyderco's price.

    John
     
  16. Mizar

    Mizar Member

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    I meant the CPM type of steels, it's just a typo coming from local knife forums. OK, my statement is incorrect, I admit that. But can you provide data to back up your claim? Because that's what we are discussing essentially for two pages. Like I already said, I prefer carbon steel blades for most occasions and I don't argue with you, but we need some type of comparison tests and etc. at least to see what one can expect from a given steel.
     
  17. JShirley

    JShirley Administrator Staff Member

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    Said "claim" being that a high hardness is appropriate for small knives but not necessarily large ones, or that leverage increases as tools get longer?
     
  18. Mizar

    Mizar Member

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    No, this:
    So, some interesting data concerning the impact toughness, because it is an important factor for the large blade knives:
    First value is in Joules and the second is hardness by Rockwell C scale:

    M4 - 15J @ 64
    440C - 22J @ 58
    CPM S90V - 26J @ 58
    D2 - 30J @ 59
    CPM M4 - 38J @ 63.5
    S30V - 38J @ 58-60?
    M390 - 41J/sq cm @ 58? and 32J/sq cm @ 63 (unknown test method)

    O1 - 41J @ 62 (61 to 63)
    3V - 53J @ 62 and 113 @ 58
    A2 - 56J @ 60 and 42J @ 61
    L6 - 58J @ 61 and 93J @ 57
    S7 - 169J @ 57
    S5 - 198J @ 58-59
    4340 - 55J @ 57 (Charpy V notch test)

    It is copied from here: http://www.cliffstamp.com/knives/forum/read.php?17,12501
     
    Last edited: Jan 24, 2018
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  19. JShirley

    JShirley Administrator Staff Member

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    I notice you left out the parts about that test being designed to test structural strength in ship steels, not impact resistance in knives...but you can clearly see the phenomenon I described about rc by looking at what happens to 3V by lowering from 62 to 58.

    But, sure, let's see what Cliff has to say about 5160:
     
  20. Mizar

    Mizar Member

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    Well, we have to start from somewhere, don't we? I would be grateful if you show me a more knife-specific tests performed, that would answer the OP's question.
     
  21. JShirley

    JShirley Administrator Staff Member

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    Ah. Very good.

    The OP wondered if there's any remaining advantage to nonstainless carbon steels. IMO- but a considered opinion with a lot of years of experience behind it- those advantages, as a few others have said in thread, are in cost, and in building large hard-use knives that can be easily resharpened.
     
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  22. Elkins45

    Elkins45 Member

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    To paraphrase Ronald Reagan, “It’s not that knife buyers are ignorant, it’s just that so much of what they know isn’t true” and parts of this thread illustrates that.

    Any blanket statement about a steel being “best” that doesn’t include a description of intended use, heat treat, tempering and blade/edge geometry is mostly just noise. Carbon steel is easier to sharpen? I have a blade made from a full hardness power hacksaw blade that a Japanese water stone won’t touch. I won’t even try to touch it up with anything other than a belt sander. Stainless isn’t tough? Ask Ray Ennis (Entrek) how tough plain old 440C can be.

    The amount of carbon in a blade matters, but how it is distributed is a huge factor. The quality of the heat treat matters even more. I have a Beretta Loveless Hunter that’s made from AUS-8 steel, which is not generally regarded as a high end stainless. However the heat treat (done by Moki) is about as perfect as can be, and the knife takes an exceptionally sharp and polished edge. As a comparison, Old Hickory does a very nice job with their 1095 kitchen knives. So you have a very respectable carbon steel vs a low-end stainless and in my experience the edge sharpness and edge retention are about the same. And both are easy to sharpen.

    Almost all modern knife steels are better than 99% of users need them to be. I would absolutely put blade shape and edge geometry above blade steel when selecting a knife from a reputable maker.
     
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  23. JohnKSa

    JohnKSa Moderator Staff Member

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    Yup. 4 points on the RC scale result in impact resistance more than doubling. That pinpoints the problem.

    Someone says that Steel X is 2 times tougher than Steel Y, but unless you have toughness numbers at identical hardnesses, you don't really know which one is tougher.
    I wouldn't disagree. What would be nice to know is if that is because 5160 is actually tougher than the Spyderco steel or because the kukri is simply tempered to take that kind of abuse while the Spyderco is tempered as hard as they can make it without worrying about edge chipping.

    But what I'd really like to know is if it's possible to make any reasonable "rule of thumb" type statement about the relative toughness of high-carbon stainless steels and high-carbon "non-stainless" steels. The more I look into this the more I think that such an statement is going to be very difficult to either prove or disprove.
    Which is pretty much my own advice about cast vs forged (with respect to guns) thrown back at me. :D It's the design and the manufacturer's dedication to quality/durability and to customer satisfaction that are the real issues that should be considered when buying a gun, NOT whether it's made from cast or forged parts.

    Still, it's a very interesting discussion--at least to a knife geek like me. I'll keep trying to learn about the topic because I find it fun to do so--even if I can never really answer the question fully.
     
  24. JShirley

    JShirley Administrator Staff Member

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    I'm sure my Spydie DD CPM154 will hold an edge longer, and probably take a better edge than my kuks. And my kuks are much less likely to crack, and more likely to roll an edge than chip.
     
  25. Cowhide Cliff

    Cowhide Cliff Member

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    Things become old news and nobody wants it anymore. Rename it and don't tell anybody and people will love it for what it is. Like the 40CP was basically a 440C made by powdered metal technology. I got some on the I think one and only batch that was made of it and it was some great steel and made some really nice serviceable blades. I think the only reason it didn't go over is because people found out it was essentially 440C and wasn't some new great thing. As I said all of the new popular stainless knife steels are a close variation of 440C, ATS34, 154CM. The XHP which is probably the most popular of the steels custom makers are using now is essentially a cross between 440C and D2 made via powdered metal. It is great stuff and I love it but in all honesty the 40CP was easier to work with and made just as good of blade, even though the XHP probably will take more abuse it is harder to resharpen so there is always that trade off.
     
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