A2 steel - History and Properties

Discussion in 'The Kitchen Knife' started by Larrin, Apr 22, 2019.

Help Support Kitchen Knife Forums by donating:

  1. Apr 22, 2019 #1

    Larrin

    Larrin

    Larrin

    Senior Member

    Joined:
    Mar 13, 2011
    Messages:
    565
  2. Apr 22, 2019 #2

    Barmoley

    Barmoley

    Barmoley

    Supporting Member

    Joined:
    Aug 13, 2016
    Messages:
    1,397
    Great article as usual. As always some surprising, for me, findings. I expected A2 to be relatively tougher to be honest. Good to know where it stands as compared to others though. Also, quiet surprised by relative standing of cpm-154cm, I've been looking down on it, but it looks like it and its cousin rwl34 can make an excellent all around kitchen knife.
     
  3. Apr 22, 2019 #3

    Larrin

    Larrin

    Larrin

    Senior Member

    Joined:
    Mar 13, 2011
    Messages:
    565
    Yes that CPM-154 looks very high now as we are filling out the chart. Hopefully we can do some more CPM-154 testing to see if it is replicated.
     
  4. Apr 22, 2019 #4

    merlijny2k

    merlijny2k

    merlijny2k

    Senior Member

    Joined:
    Mar 3, 2016
    Messages:
    590
    Nice read Thanks
     
  5. Apr 23, 2019 #5

    M1k3

    M1k3

    M1k3

    Senior Member

    Joined:
    Jul 28, 2018
    Messages:
    708
    Another nice read. Thanks!
     
  6. Apr 23, 2019 #6

    Larrin

    Larrin

    Larrin

    Senior Member

    Joined:
    Mar 13, 2011
    Messages:
    565
    Thanks guys
     
  7. Apr 28, 2019 #7

    dan

    dan

    dan

    Well-Known Member

    Joined:
    Dec 20, 2018
    Messages:
    83
    Location:
    Seattle, USA
    Larrin, cool write-up (again). I'm a little mentally burned out today but I'll give it a better read tomorrow. One thing popped into my mind while reading your article and I think you'd know the answer. In regular carbon steels (carbon and iron only), austenitizing forms one uniform phase with the carbon (relatively) uniformly mixed throughout the iron. What happens during austenitization for steels with other elemental components? Specifically, I'd be curious about carbide-formers like silicon or vanadium.
     
  8. Apr 28, 2019 #8

    Vladimir

    Vladimir

    Vladimir

    Senior Member

    Joined:
    Mar 4, 2011
    Messages:
    358
    Location:
    Ukraine
    if I'm not mistaken knives from Heiji semi-stainless steel, this is analog A2
     
  9. Apr 28, 2019 #9
    The exact steel in SemiStainless Heji knives is not know, so saying that it is A2 is a pure speculation - unless you have information available that the rest of us do not have access to.
     
  10. Apr 28, 2019 #10

    Vladimir

    Vladimir

    Vladimir

    Senior Member

    Joined:
    Mar 4, 2011
    Messages:
    358
    Location:
    Ukraine
    I read somewhere that Heiji uses SKD-12 (analog A2). I am not an expert, I say what I read on the Internet, I cannot give a link and as I said ealrier I could be wrong, I hope someone can clarify this.
     
  11. Apr 28, 2019 #11

    Larrin

    Larrin

    Larrin

    Senior Member

    Joined:
    Mar 13, 2011
    Messages:
    565
    High carbon steels like 1095, W1, white steel, etc. still have carbides present after austenitizing at recommended temperatures. Silicon is not a carbide former in steel. Vanadium would mean vanadium carbides, generally.
     
  12. Apr 29, 2019 #12

    dan

    dan

    dan

    Well-Known Member

    Joined:
    Dec 20, 2018
    Messages:
    83
    Location:
    Seattle, USA
    I know this is off-topic so I could bring it somewhere else if you prefer, but this topic has piqued my interest. I don't do a lot of metallurgy but I do other types of research in the materials domain... more theoretical.

    I guess I think of the phase diagram and imagine that all the carbides dissolve into the austenitic phase quickly. But your comments imply that the carbides don't complete the austenitic transition during the typical temperature treatment. In the case of carbon steels - say compositions around the eutectic point - 'carbide' is referring to cementite (right?). Does the cementite not have sufficient time to dissolve into austenite, or is there too little thermal energy for it to happen on a realistic time scale?

    I always imagined the point of austenitization is to essentially 'reset' the metal of any prior thermal cycling and cold working or other stress deformations. But... if the cementite never dissolves into the austenitic phase, then the prior thermal cycling would play a role in the future performance of the steel. Is that fair to say?
     
  13. Apr 29, 2019 #13

    Eloh

    Eloh

    Eloh

    Well-Known Member

    Joined:
    Dec 20, 2015
    Messages:
    230
    Jms lists them as skd12. And since they have nothing to gain from lying about it or even speculating about it I think it is indeed what they use.
     
  14. Apr 29, 2019 #14
    Oh, I missed that info on JMS webpage. I am surprised though as my understanding was that this information was not to be made public (other Jon would have published it). I do not want to speculate whether what JMS states is correct or not. I have learned to believe less in this regard ...
     
  15. Apr 29, 2019 #15

    Knife2meatu

    Knife2meatu

    Knife2meatu

    Well-Known Member

    Joined:
    Oct 28, 2018
    Messages:
    275
    Location:
    Montreal
    Oh dear, the lack of a 'Like' button is really going to sting in the context of a new @Larrin thread.
     
  16. Apr 29, 2019 #16

    Larrin

    Larrin

    Larrin

    Senior Member

    Joined:
    Mar 13, 2011
    Messages:
    565
    At temperatures/compositions where all of the carbide will dissolve, some time is necessary. Read my article on austenitizing: https://knifesteelnerds.com/2018/02/28/austenitizing-part-1-what-it-is/

    I don't think the point of austenitization is to reset anything, the point of it is to quench to form hard martensite. What you're describing is closer to normalization.
     
  17. Apr 29, 2019 #17

    M1k3

    M1k3

    M1k3

    Senior Member

    Joined:
    Jul 28, 2018
    Messages:
    708
    +1
     
  18. Apr 29, 2019 #18

    Larrin

    Larrin

    Larrin

    Senior Member

    Joined:
    Mar 13, 2011
    Messages:
    565
    I like the like button. It must be cause I'm so cool and hip and change with the times. I'm sad to see it go.
     
  19. Apr 30, 2019 #19

    Knife2meatu

    Knife2meatu

    Knife2meatu

    Well-Known Member

    Joined:
    Oct 28, 2018
    Messages:
    275
    Location:
    Montreal
    That was a fascinating read, as usual.
     
  20. Apr 30, 2019 #20

    dwalker

    dwalker

    dwalker

    Senior Member

    Joined:
    May 6, 2016
    Messages:
    1,175
    JMS?
     

Share This Page