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Knife Steel Question

Discussion in 'Knives' started by Polynikes07, Feb 18, 2010.

    Polynikes07 Empty Pockets

    So I was browsing SOG knives earlier and noticed that on several knives they use Aus 6 steel. I've also seen knives from other companies with Aus 4. I was under the impression that Aus 8A was the best Aus steel. I've also heard that the steel type doesn't matter so much as the heat treatment.

    I was just curious if someone could give me the rundown on the Aus steel. Is SOG's heat treatment able to make Aus 6 perform at a better level?

    CV90 Loaded Pockets

    I own 2 knives made from AUS6 steel (both CRKT, not SOG). The steel is easy to sharpen, the edge retention isn't very good due to low carbon content, but the corrosion resistance is excellent. I have no experience with AUS6 SOG knives, but I guess the steel performs similar to CRKT AUS6.

    AUS8 performs similar to 440C. It's the best from the AUS steel grades. Lower grades include AUS4 and AUS6 /AUS6M.

    VT-aroo Loaded Pockets

    Aus-10 exists, but is not used all that much. My CRKT in AUS-6 is about what you said, easy to sharpen, easy to dull. Knives from several sources in AUS-8 seem to do a pretty good job of edge holding.
    AUS 4 looks chemically like 420 HC. Which means it will be pretty soft, but highly resistant to corrosion. I have never had a knife in that steel, but I get good use out of my Buck knives in 420 HC.

    Rawls Loaded Pockets

    Here is an AWESOME primer on metallurgy and steel in knife blades:

    Knife Steel FAQ by Joe Talmadge

    This link should be pinned to the top of the knife section board. It is both well written and informative. His explanation of the different attributes in a blade is really helpful to me.

    Polynikes07 Empty Pockets

    Awesome FAQ! That really helped, thanks! :hug:

    Monocrom Loaded Pockets

    Isn't that the Japanese version of good old reliable 440C?

    VT-aroo Loaded Pockets

    that is what I thought.

    Lord Bear Loaded Pockets

    Rawls, thanks for that link to "Knife Steel FAQ". Fascinating read. Just wish it included Spyderco's nitrogen based H1 steel. Probably put together by Mr. Talmadge before H1 came on the scene.

    Polynikes07 Empty Pockets

    I was hoping for that to but the FAQ is a little dated, and H1 is relatively new.

    Coolio Loaded Pockets

    From what I've read:

    AUS-10 ~ 440C
    AUS-8 ~ 440B
    AUS-6 ~ 440A

    AUS-8 actually has about the same amount of Carbon as 440A but adds Vanadium which helps build carbides from what I understand and has less Chromium than the 440 series.

    Interactive Knife Steel Chart

    Joe Talmadge Loaded Pockets

    I really need to update that FAQ, there's probably as many as 10 steels in use now that weren't in use then. Glad you guys found it useful

    Lord Bear Loaded Pockets

    Whooaa! Mr Talmadge in the flesh! (Cyber flesh that is)! Sir, I thank you again. The point you made about different edge angles for different steels got me rethinking about reprofiling all my S30V's. I just wish Spyderco would make a Sharpmaker base at 20degrees along with the 30 and 40 degree pre set angles. An update would be really appreciated sir.
    P.S. I'm gonna postmark that FAQ since there are points I will probably check over more than once.

    Lord Bear Loaded Pockets

    Question: Am I correct in assuming S30V is just a "contraction" of CPM S30V? Or is there a difference?
    (Hilarious aside...From Mr Talmadge's FAQ, apparently "Carbon V is whatever steel they happen to be using at the time." And here I thought it was a "proprietary steel"! Cracked me up as I chalked another one up to experience.)

    carrot Loaded Pockets

    Yes, there's only one S30V, the CPM S30V kind.

    rueingeni Loaded Pockets

    In my experience AUS8 takes a razor edge, but it's not very tough, I got chips in the edge from trying to cut FRN. I don't know about edge retention, I didn't really use it enough to find out, but I've heard it's poor.

    Monocrom Loaded Pockets

    You heard wrong. Edge-retention is quite good. Keep in mind that AUS8 has an American twin, 440B. When you buy a stainless steel Randall Made knife, you're getting 440B. If it's good enough to be used by that brand, it's far from poor.

    Lord Bear Loaded Pockets

    Acknowledged Carrot. Thanks. You sir are a fountain of knowledge.
    (Oops! Almost forgot.... :bow: :bow: )

    Joe Talmadge Loaded Pockets

    For me, before I dig in too deep I ask, poor compared to what? I would agree that for general use, most people won't find 8A's edge retention "poor", though often noticeably less than something like ATS-34, much less something like S60V. Of course, the opposite is possible also ... 8A will be tougher than both ATS-34 and S60V, so if you've got some odd usage that requires a better toughness, 8A could hold its edge *better* than ATS-34 or S60V. Edge retention is a function of strength, toughness, and wear resistance, and depending on how you use the knife, your usage could stress some factor or other to favor a steel that everyone knows doesn't hold its edge as well.

    rueingeni, don't know why you got chips in your 8A blade when trying to cut FRN. Maybe the edge was too thin, maybe the manufacturer blew the heat treat or overheated the edge during final sharpening (something that's more common than you'd think). But overall, I find 8A a perfectly serviceable steel for an EDC folder (though I prefer other steels), and very easy to put an insanely sharp on edge it. For me, more likely to get dull due to its lack of strength and wear resistance than toughness. Not doubting your experience, just wondering if there's some other factor at play we don't understand.

    Joe Talmadge Loaded Pockets

    That'd be cool. But in the meantime, if you want to experiment with lower angles, and only have the Sharpmaker to play with, try this. You're using the sharpmaker rather than sharpening freehand because the Sharpmaker helps hold the edge better (right?). So what if you use the sharpmaker only to set the final edge at 30 degrees, but freehand a 20ish degree "back bevel" first? Performance will not suffer if the 20 degree back bevel is not perfect, provided you get the 30-degree finishing edge perfect. To get the 20 degree back bevel, put the knife on the Sharpmaker as if you were going to sharpen regularly, but instead of holding the blade perfectly straight up and down, tilt the spine slightly towards the stone. Remember what the tilt looks and feels like and try to keep it constant -- that's your sub-30-degree back bevel. Go through the backbevel steps you usually follow, then lay down the final 30 degree edge by keeping the spine straight up and down. You should see a really sweet performance improvement if you normally sharpen your knives with a 30-degree back bevel and 40-degree final edge.

    Sirvive Loaded Pockets

    very interesting facts guys...

    :popcorn: