Am I mistaken? Cold Steel O1 vs SK-5 weird review...

Discussion in 'General Knife Discussion' started by arijer, Nov 6, 2014.

  1. arijer


    Jul 13, 2009
    Ok, so seriously I am not ragging on the guy. It was a interesting read. But it confuses me a bit. I consider myself very much a novice still. But I don't agree with the this gentleman....
    Basically what he is saying is SK-5 is a better steel and more rust resistant then O1?? Isn't SK5 just a version of 1085, which is still a high carbon steel that rusts? there is no stainless aspect to 1085/SK5 is there? And O1 is a upgraded 1095... from all I read it holds a edge a bit better then even 1095 and is tough as I need a knife to be. I have never had a problem sharpening O1, no S90V... ugh lol

    So.... how does he reach his conclusion that it is a downgrade? I'm lost. Educate me gurus, am i off?

    Here is the review he wrote and the link (am i breaking a rule here? hope not)

    "I thought fellow fans of bushcraft knives might be curious about this news: Currently, some of Cold Steel’s most popular knives (the Trail Master and the Recon Scout) are made of SK5 which they are planning to switch to O1. As I noted in my review of the Trail Master, SK5 is an excellent steel of moderate hardness and good rust resistance. Such a big knife needs a more forgiving, less brittle steel. SK5 is hard enough to take and hold a good edge, but it grinds easily for sharpening, and it is just springy enough to be used as a chopper without chipping the edge or breaking the blade. Below is a note on SK5 steel from

    SK-5 : A high carbon steel made in Japan. It is the Japanese equivalent of 1080. It has a high hardenability. It has a mixture of carbon-rich martensite and small un-dissolved carbides. The carbides increase wear resistance. This helps to create a good balance between toughness and edge retention. This steel is often used for making hand tools.

    Cold Steel is now switching these knives to O1 and billing it as a “superior” steel. Sadly, in the last few years Cold Steel has been downgrading some steels (no one knows why, except maybe to increase profit margins). The worst case of this was the Leatherneck, a once excellent version of the Ka-bar USMC knife which, when made from SK5, was excellent. Cold Steel ruined the Leatherneck when they changed the steel to cheap 4116 stainless, an unimpressive metal often used to make nail clippers.

    Now, O1 is not a bad metal, but it is not exactly the “superior” metal Cold Steel bills it as. Here is’s description of it:

    O-1 : An [sic] good oil hardening, cold worked tool steel. It has excellent edge retention and toughness. But it is hard to grind and has very low corrosion resistance. It is popular among forgers because it is very forgiving and can be heat treated repeatedly if a mistake is made.

    After doing a fair bit of research, I am left with the impression that O1 is too hard a steel to be good for a large knife like the Trail Master and Recon Scout. Reports state that the edge may take small chips and that it is quite hard to sharpen. Also that it is very prone to rusting. I suspect Cold Steel’s real reasons for the switch have nothing to do with superior quality, but that it is easier to get in the USA and more flexible to work with.

    I really liked Cold Steel once. It’s too bad they’ve been making the moves they have in the last couple years under new management. They are slowly alienating many of their once devoted aficionados. For my part, I’m glad I bought two Trail Masters before the big change to O1. I feel a more resilient, rust-resistant steel has far more bushcraft application than O-1. I would even consider O-1 a downgrade for a smaller knife given its proneness to rusting unless one resides in an arid region such as the American desert southwest."
  2. Freman Bloodglaive

    Freman Bloodglaive

    Apr 14, 2013
    Everyone I've heard talk about the O-1 change regard it as an upgrade. For the rest, Cold Steel are introducing steels like XHP and 3V into their range also, and those are definitely quality steels.

    Cold Steel did change their SK5 for 4116 in the Leatherneck, but from my experience of 4116 that was more a sideways change than a downgrade. As I understand it they required a stainless blade for a contract and they basically had a choice of 4116 or AUS8. Being used for nail clippers is a pretty pointless criticism. Some knife steels are used in ball bearings, or truck springs. Steel has multiple uses.
    Last edited: Nov 7, 2014
  3. The Mastiff

    The Mastiff Gold Member Gold Member

    Apr 21, 2006
    Alright, I'm just guessing on this. The "O-1" that Cold steel is using in their taiwan made line is likely YK 30. It's the same thing used in CKRT knives made there and probably used by cold steel for simple convenience. I've heard it described as "O-2", and "O-1". I asked over on the Cold Steel website and they wouldn't even pretend to answer it. I don't know why as YK 30 is a fine steel. Here it is composition wise to SK-5 and O-1 lower down on the chart.

    Note: the biggest changes are YK30 ( or O-1 for that matter) has higher levels of Carbon. The only notable other difference would be the addition of .25 of 1% Nickel in YK30 ( but not O-1. Most O-1 have a tiny bit of tungsten. Anywhere from .15% to .50% depending on the company purchased from. In addition, every batch, or "heat" will vary from batch to batch somewhat and will stay within certain limits ( .85% to .1.05% carbon for O-1 on the standardized composition for that grade). XYZ steel company might run a batch with 1.04% carbon, then the next batch might have .94%.. As recycled steels are used more and more there will often be other elements in batches not in the official O-1 composition. The steel supplier ( the guys that buy if from the foundry and roll it and grind it into useful sizes for knives ( visit Niagara speciality metals : They are great people). So , the steel supplier will send a sheet that lists the actual composition that batch was tested to have. I've seen things like aluminium and copper show up in steels that didn't have these elements in their standardized compositions because of the recycled material. These compositions can help heat treaters tweak heat treats and are kept on file in case the 1 inch bolts it was made in failed and they want to know why when they do forensics on the failure mode. I Digress though.

    SK5 and O-1, and even YK30 just aren't that different to the point they would cause large changes in attributes and capabilities. Higher carbon will technically make steel less tough but in this case there would be more a difference from differing heat treats than from the compositions of the steel. The steels are both excellent if done right. Both can fail if not done properly.

    I have all of the steels in question and will say quite frankly that the difference in corrosion resistance is more due to surface finish, as well as the heat treat and tempering. Likewise wear resistance (if done at same hardness) will be pretty similar. O-1 , true O-1 that meets the specs from a good foundry and a good batch might be able to achieve slightly better grain structure, but the difference would not be any where near the improvement in grain structure acheived from the powder process. Example, from 154cm to CPM 154. .

    Anyway, buy whatever model you want. They will all be good and all need care to keep rust away.. I decided not to get the "O-1" trailmaster as it's not going to be much better. I've had several SK5 knives I really like. I have some O-1 knives I really like but they have, IMO, a better heat treat than the Cold steels. ( BHK, and now "war horse? or something they are now called. ) They really get all they can out of O1. Better than the knife I made out of O-1. :) Spyderco gets a good all around performing knife out of their O-1 Bushcrafter. In SK5, the Browning "Crowell Barker" is I believe SK5 sold as 1080, 1085, or just High Carbon steel. Whatever it is it brings excellent operformance to the customer for a very low price, in relation to what you get.

    Last edited: Nov 7, 2014

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