AR-RPM9 - New PM Steel from Artisan?

Discussion in 'General Knife Discussion' started by Chronovore, Jul 2, 2020.

  1. John_0917

    John_0917 Gold Member Gold Member

    Apr 15, 2014
    I’m not doubting the ability to make PM steel there, I meant that I find it unlikely that they would have invented an alloy that is unique and special that no one else has though of yet.
     
    DMG likes this.
  2. Larrin

    Larrin KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 17, 2004
    The Chinese steel companies are capable of it though Artisan of course isn’t given that they are not metallurgists. And now that the composition has been released we have seen that it isn’t a new composition anyway.
     
  3. Chronovore

    Chronovore Basic Member Basic Member

    908
    Aug 29, 2019
    Indeed, they recently clarified that the "rare earth" component is just trace elements. However, what counts as a "new" composition? Like I said earlier, this looks to be in the same ballpark as 9Cr18Mov and Acuto 440 but isn't an exact match for either. I've been pretty happy with those steels on inexpensive budget knives from Civivi, Real Steel, and Kizer. I'm no metallurgist but based on those experiences, that doesn't sound like a bad starting concept for a PM budget steel.

    Any idea what that tiny bit of cobalt is supposed to accomplish?
     
    BITEME likes this.
  4. dirc

    dirc

    Jan 31, 2018
    well, cobalt adds something & @Larrin has written about it: (but in the context of vg10) - I think the lessons apply to this 'new' steel also

    https://knifesteelnerds.com/2018/05/14/why-there-is-cobalt-in-vg-10/

    the tldr version (imho) is they've added a bit of cobalt to avoid having to spend $ on cryo (cold) in heat treatment

    and @Larrin says (in the vg10 article) "cobalt addition gives the steel higher hardness with high temperature tempering and therefore allows it to be used with surface coatings that require high temperature application. That is the most likely reason for adding cobalt."
     
    Last edited: Oct 4, 2020
  5. Pomsbz

    Pomsbz

    Jul 31, 2015
    Here we go again.
     
  6. Larrin

    Larrin KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 17, 2004
    Given the misunderstandings in the rest of the composition (nickel is not added, just a maximum), I'm not sure the cobalt is indeed being added. My hunch is the cobalt is also a maximum. In other words, it is 9Cr18MoV. Even if they were adding 0.3% cobalt, it wouldn't make the steel measurably different.
     
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  7. Lodd

    Lodd Gold Member Gold Member

    576
    Jan 23, 2015
    It's a good thing we know the composition now. It looks like we've got a new trend on our hands with knife companies getting their own proprietary steel. I would like to point out that a steel with an unknown composition is a mystery steel. You shouldn't buy knives in mystery steels. Going forward, we should be alert on this, as I expect more companies will follow in this trend.
     
  8. Larrin

    Larrin KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 17, 2004
    I wouldn't say that proprietary steels are a new thing. In the past, when companies have had secret steels they end up being something that was already available under a different name. Now Spyderco has a proprietary steel but the composition was released because it is in fact a proprietary steel. "Proprietary" steel is generally just marketing.
     
    Lee D likes this.
  9. Lodd

    Lodd Gold Member Gold Member

    576
    Jan 23, 2015
    I agree. Case and Victorinox come to mind. But for a knife manufacturer to do so* is no small step (in terms of purchasing and, I imagine, production processes.). So, when multiple companies announce such a step within the span of a year, it stands out.

    The bit about marketing is exactly why we should be alert. At least we know that Case's Trusharp is 420. In the thread we had a while ago about SPY27 we established that it was enough of a change to be considered a new steel on its' own standing (although still comparable to S35VN). But how many companies would be tempted just to rebrand an existing steel without being entirely transparant about it?

    If AR-RPM9 is indeed just 9Cr18MoV, as you suspect, it leaves a bad taste in mouth when a company tries to obfuscate this.

    Edit:

    * commit to using their own proprietary steel
     
  10. Larrin

    Larrin KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 17, 2004
    Based on comments from Artisan I don't think they understand what the steel company is telling them.
     
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  11. Lodd

    Lodd Gold Member Gold Member

    576
    Jan 23, 2015
    Somehow that sounds even worse, lol :D
     
  12. Brhowser87

    Brhowser87

    Aug 3, 2016
    I'm glad we have someone here (larrin) that can break it down for us layman (me) but some people no matter what is said to the contrary will have something negative to say. Will only find out once we get our hands on it.
     
  13. Chronovore

    Chronovore Basic Member Basic Member

    908
    Aug 29, 2019
    I really hope that isn't the case. I watched some of the longer videos discussing this steel. Russel made it sound like there was some kind of brainstorming behind AR-RPM9. I'd like to be charitable but I guess we can't know for sure.

    So if this is just the recipe for 9Cr18Mov, but with a PM process and maybe some tighter controls, is that a bad thing? Isn't that still a new thing? Might that offer some tangible benefits on the level of $50 budget knives?
     
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  14. Larrin

    Larrin KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 17, 2004
    The question of what the steel is and how it’s advertised is separate from the question of what the properties will actually be. The steel would be better than D2, in my opinion, since it would have better toughness and corrosion resistance with only a bit worse edge retention. Not an exciting combination of properties but decent.
     
    jstn likes this.
  15. Dirk

    Dirk Moderator Moderator

    Mar 19, 1999
    This is all interesting. When I was told the formula a while back, I was thinking it was a modification of 440B. Didn't think about 9cr.

    I am actually very excited that companies are trying to figure out ways to improve lower end steel. While I love the performance achieved with new alloys, they are expensive and often require very meticulous heat treat recipes.

    Many of the attempts to find a better low end steel have fallen short of the goal. Heck, many of the attempts at the high end stuff haven't reached their goals either. I am all for the effort and hope more companies join the effort.

    As for RPM-9, my sample Arroyos have been doing very well. I haven't given them a hard work out yet. Mostly day to day chores. The edge has held well, no rusting after tomato cutting. I'll take it over D2 any day of the week.
     
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  16. Larrin

    Larrin KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 17, 2004
    9Cr18MoV is an alternate name for 1.4112, which is the German version of 440B.
     
  17. Chronovore

    Chronovore Basic Member Basic Member

    908
    Aug 29, 2019
    Thanks for sharing this. The only firsthand accounts I've seen so far are from Eugene Kwon and Michael Emler. Both have been positive. It sounds like edge retention is decent and corrosion resistance is excellent. The main thing Emler noted is that this steel responds especially well to stropping. This is only a few data points but taken with the expected prices, that's right up my alley for budget EDC.

    I'll be ordering both a Sea Snake and an Arroyo as soon as they become available. Besides liking both of those designs, the combination of fixed and folding with different blade shapes will help me to carry this steel exclusively until I get a feel for it.
     
  18. Dirk

    Dirk Moderator Moderator

    Mar 19, 1999
    While I don't expect it to "punch above its weight class", I am hopeful it will be a solid performer and be towards the top of budget steels.
     
  19. dirc

    dirc

    Jan 31, 2018
    I'm interested to hear test results, but I think 14c28n will remain the budget stainless champ ... yes I'm biased
    ...my kershaw leek uses it, as does my ruike jaeger fixed blade
    both of which impress me after long use
     
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  20. jstn

    jstn Gold Member Gold Member

    Jun 27, 2012
    Ruike jaeger is one of my favorite budget blades. I’m gonna pick up an Arroyo soon, mostly because I love Pinkerton’s designs, with the added bonus of trying the new steel.
     
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