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SV30 toughness

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by elasmonut, Feb 22, 2006.

  1. elasmonut

    elasmonut

    206
    Feb 15, 2006
    I know this is one of THOSE questions but bear with I'm new here.I've heard alot about SV30 being the greatest stainless ever with edge holding on par or better than D2 ats34 and BG42,with supposedly superior toughness but I haven't found any reports on destructive test comparisons,and have read about chipping problems in production sv30 blades.So is it a dramatic improvement or am I better to save my cash and buy twice as much ATS34?
     
  2. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Do you mean S30V? It is a super stainless steel.Hard to grind,real hard to polish,makes a superb knife.Many find ATS-34 to be easier to work with.The new CPM154 may be the best combo of workability - toughness for many makers.BTW an SV30 is a Toyota, and they make lousy knives.
     
  3. F. Allin Kahrl

    F. Allin Kahrl

    211
    Aug 20, 2004
    One of the best sources of steel data is Crucible Steel's data sheets. They cover formulation, application, heat treating, and frequently have competitive comparisons between steels. They're available on Crucible's website.

    They test toughness with a Charpy machine, which is destructive. It's not applied destructive testing, like making a knife out of the stuff and breaking it, but it's a useful guideline.

    The sheet on S30V says that S30V has 4 times the transverse toughness of 154CM (Crucible's version of ATS-34) or 440C at recommended hardness, but I check and see that S30V has half the transverse toughness of D-2.

    There's more data in there about wear and corrosion resistance, too. Hopefully you can find the info you're looking for.

    -Allin
     
  4. mete

    mete Gold Member Gold Member

    Jun 10, 2003
    One of the problems of complex steels made by normal methods is that properties are different in the three different directions to the rolling direction. This is especially true of transverse impact strength. The CPM method eliminates much of this problem and gives finer and more evenly distributed carbides also. I would like to see more comments from makers and users on the CPM 154CM. This may be the best compromise.
     
  5. Darrel Ralph

    Darrel Ralph Moderator Moderator

    Dec 14, 1998
    Mete all,
    For years we "Knife Makers" have found that samples of steels spec sheets made with .5 inch thick sample do not pertain to knife edges.
    Steel changes when they are .015-.03 thick at the edge.
    Blades are in a different class all together.

    The new CPM154 is IMHO a fantastic compromise for CPMS30V. S30v is good steel with some factors that I have problems with. AS for grinding it is BUTTER compared to S90V so that has no effect on me coming from D2 and S90V being the steels that I used on my folders for many years.

    S30V Still has corrosion problems.
    Crucible says they fixed it but I don’t see it in my shop.
    The other thing is once you are over a 400 grit finish you see the grain of the steel.
    HI polish is a no no.
    The CPM 154 will mirror and the stain resistance is fantastic.
    The other thing that I like it the edge that can be achieved on the CPM 154. It is brutally sharp. That is two steps above WICKED sharp. It reminds me of talonite sharp.
    You know one that cuts you every time you make a blade.
    The edge retention in my tests is within 10 percent of S30V. That is close enough. The bend tests are very good. The edge impact is very good also.
    So I am very pleased with the CPM 154. It is NOT like 154 cm. We asked Crucible to name it differently but they did not. We had the same problems with 420v being renamed S90v because of the problems that people had with 420 steel.
    Anyway I am using it and I have to say that to this point I am putting my endorsement on this steel.
    One more thing is that from the words of the Manager at crucible…. CPM154 is very near aircraft quality.
    This means that there will not be large element differences from heat to heat.
    Consistence is the key when making blades.



    Just my take on this steel.
     
  6. John Andrews

    John Andrews

    Jan 24, 2003
    That is very interesting, Mr. Ralph. I thank you for clearing that up in my head, too.
     
  7. Danbo

    Danbo Platinum Member Platinum Member

    Nov 28, 1999
    Thanks, Darrel. Makes me glad I picked up a couple of 3 ft bars from Pop's, while I was down in Little Rock a couple of weeks ago. :thumbup: :)
     
  8. Darrel Ralph

    Darrel Ralph Moderator Moderator

    Dec 14, 1998
    Fellas,
    Please give this steel a try. I also havent tried it yet but I will do a diff temper on it to see what I get from that experience. WOO HOO!
     
  9. elasmonut

    elasmonut

    206
    Feb 15, 2006
    thanks guys your feedback has been great,and yes I did mean S30V.I,d read the crucible charts for this steel and compared to user reports on production stuff came away with mixed feelings about it.The corrosion resistance is not such an issue, on par with D2 is good enough for me I'm prepared to wipe it down every now and then.Nor is the polish as I was looking to use it in hard use/tactical style blades.I was more hoping for a steel with good toughness but better corrosion resistance than say A2,or CPM3V.Thanks for your help I'm of to the crucible site now to check out CPM 154,and will probably be back with more questions,later
     
  10. elasmonut

    elasmonut

    206
    Feb 15, 2006
    O.K. I just looked on the crucible site and nothing about CPM 154 does anyone have the chemical breakdown of this steel
     
  11. mete

    mete Gold Member Gold Member

    Jun 10, 2003
    It's the same composition as 154CM [though some say with a small addition of V] .It's the method of manufacture that's different.
     
  12. tj499

    tj499

    3
    Feb 19, 2006
    It's like this- get two jars, fill one with large marbles and the other with small marbles, you will notice the large marbles have less surface contact with eachother and small marbles have alot of surface contact with each other, more surface contact means a better bond (like a wider tire on the race track). What I mean to say is when any metal is bonded based on a smaller particle (powder vs granule) you will get a metal that has toughness, edge retention & flexibility regardless of the metal.
     
  13. tj499

    tj499

    3
    Feb 19, 2006
    I have a s30v strider that I hone on an arkansas hard black stone (1000 grit?) my edge is shiny, I can shave my face with it and it will cut down through a large piece of paper effortlesly. I borderline abuse my knives when I am hunting and it still hones up extremely well on a hard stone, so I will choose to disagree on the sharpening properties of s30v. I humbly thank you.
     
  14. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Thanks Darrel for the assessment.I concur.
    You may have to call Crucible to order CPM154. I don't think they have it on their site yet.
    I did this recently,Thought you guys would like it:
    Take an old pair of safety glasses and replace the lenses with screening.Hand them to a person who you are showing a really sharp knife to.Tell them that they are necessary because the knife is so sharp it may cut your eyeball when you look at it! (I actually had one guy put them on.)After the strange look,the laughter starts.
     
  15. daberti

    daberti Gold Member Gold Member

    486
    Apr 2, 2005
    I' do agree with you.

    I've a Benchmade Skirmish 630, double bevelled with primary set at 24degrees with a final polishing with 3M 0.3Micron Aluminium Oxide tape
    http://www.toolsforworkingwood.com/...de=toolstore&nextpage=/extra/lappingfilm.html

    The secondary has been set at 21degrees, finished at 320grits (Apex).
    With the Apex Pro kit.

    Thus as far as polishing is concerned, S30V shows no lack.

    Then: my Skirmish has undergone lotta abuse, breaking copper wires (PC) silica ropes, synthetic climbing ropes, wood, tin can emergency opening, frequent contact with water, long trekking cutting sessions.
    All of this without ever leaving me with rust, chipping or any other sort of damage.
    In the worst ever scenario it took me ten minutes of work to bring the edge as before (I'm a maniac, last 5 minutes had being overkill).

    Last but not least: it is NOT true -basing on my experience- that taking away the wire edge from S30V bladed knives is a Mission Impossible.
    Double bevelling is the starting point to accomplish with this task, finishing primary edge with appropriate polishing tape is the last step.

    I've learned this from this forum
     
  16. yoopernauts™

    yoopernauts™ Banned BANNED

    243
    Dec 19, 2006
    I don't know if I really have a good grasp of this subject, but thanks for the info. So, what would be an example of a good quality folder made with CPM 154?
     
  17. pit man

    pit man

    782
    Nov 2, 2005
    How tough is S30V,check out the Strider test by Noss....plenty tough if it's done right !!!!!
     
  18. Jared Stenoien

    Jared Stenoien

    Dec 4, 2005
    actually...the strider test showed that it was quite a bit less tough than any of the other knives, once he actually started abusing it, he even admitted that if he'd started out by bending it he wouldnt have been able to do any of the other tests
     

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