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Call for Charpy toughness samples

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Larrin, Jan 26, 2018.

  1. jdm61

    jdm61 itinerant metal pounder Knifemaker / Craftsman / Service Provider

    Aug 12, 2005
    I just got a 26 inch long 1.25 round of the Carpenter type non-moly L6 from Hudson Tool Steel. I will be mashing it into usable shapes on the near future.
     
  2. Sando

    Sando Knife Maker Knifemaker / Craftsman / Service Provider

    963
    Jul 4, 2002
    As a heat treat non-scientist: does stress relieving before hardening have any effect on toughness after hardening? In other words, should we have some samples that have been cut, ground, drilled, and generally abused. Then try them with and without a stress relief cycle.

    Since that's what actually happens when constructing knives, it might be worth knowing if stress relief is helpful for final toughness. Or it doesn't matter?
     
  3. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    That’s an interesting question. It probably depends a lot on how much “damage” was done, and if the subsequent heat cycles erases that “damage.”

    With the m4 I was cutting on the band saw, the blade just skidded on the sheared edge, like a file skating on a hardened blade. I assume the edge of the steel work hardened, as the Rc# was below 40 on the bar. I didn’t write the number down, as it was low enough that I should have been able to cut it easily with the band saw. I did a 1200f subcritical anneal for 2h, and the m4 cut easier than the z-tuff I cut right after it.
     
  4. Larrin

    Larrin Gold Member Gold Member

    Jan 17, 2004
    Have we gotten any updates o the surface grinding of the batches sent to JT and AKS?
     
    Willie71 likes this.
  5. Storm W

    Storm W

    45
    Feb 19, 2019
    What were the hardness on those? I just got a new fill of LN last week so hopefully I'm back in business. I will try to get them done this week.
     
  6. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    I’ll check when I get back home. I tested the z-tuff, but not the M4.

    Z-tuff hardness was:

    1900fx40min, cryo 1h, 400f temper, 2hx3. Rc58-60.
    1975fx30min, cryo 1h, 400f temper, 2hx3. Rc60-63 (most readings were Rc61/62, but not all were consistent.)
    2050fx20min, cryo 1h, 400f temper, 2hx3, Rc58-64.

    I didn’t need the third temper on the 1900f sample, but I was doing the other samples with 3 tempers, and just ran them all. The 2050f sample had really inconsistent numbers. I thought there might have been decarb affecting the 1975f sample, as the samples were darker, but I ground the surface off, with no difference in numbers before and after. I suspect the 2050f sample has inconsistent structures, and possibly a carbon depleted matrix. Zapp doesn’t recommend going above 1950f. The 1975f/400f sample is only one Rc point higher than the 1925f/300f sample I did earlier. I should play with lower tempers rather than increasing austenitizing temps if we want higher hardness, assuming toughness doesn’t take a big hit.
     
    hugofeynman, rodriguez7 and Keith Nix like this.
  7. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    @Keith Nix , still up for grinding? I’ve got two conditions in a11 left, then I’m shipping this one out.

    Warren
     
  8. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013

    Last I heard from Chuck was that he was sent the wrong magnetic Chuck for his surface grinder, and had to exchange it.
     
  9. Keith Nix

    Keith Nix

    14
    Jan 3, 2018
    Yes sir! I've been popping a gasket to get in on this!
     
  10. Alpha Knife Supply

    Alpha Knife Supply Always Innovating Dealer / Materials Provider

    Oct 14, 1998
    We have the new magnetic chuck. It is installed on the surface grinder and dressed. We ground some test coupons and decided to make a fixture to hold the coupons on the magnetic chuck. The fixture should be finished by this weekend.

    Chuck
     
  11. DevinT

    DevinT KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jan 29, 2010
    Sent off 8 different heat treat samples of 5160 today for Larrin to test.

    Hoss
     
  12. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    Chuck sent this to me with my thin z-wear order. 440b looks like it’ll be relatively tough based on its chemistry. A8mod should be competing for toughest steel in our testing.

    [​IMG]D2BC78A9-BAC1-4C69-9859-A359BFE05707 by Wjkrywko, on Flickr
     
    Last edited: Mar 15, 2019
  13. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    Heat treating the last two samples tomorrow, then off in the mail. I’ll post the list of everything going when I am ready, probably Sunday.

    I spoke with Storm W today. He’s doing the higher temp M4 in high and low temp. We were discussing M2, and pushing the envelope in terms of hardness and thinness. Interesting stuff to ponder.
     
  14. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    I was out of commission with too much fun from Friday night, then a massive head cold. Steel (a11) is in the oven today. I’ll post the list later. I have a day off after two cancellations today.
     
    hugofeynman, Keith Nix and Larrin like this.
  15. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    It’s all boxed up. I’ll drop it in the mail this afternoon.
     
  16. Sando

    Sando Knife Maker Knifemaker / Craftsman / Service Provider

    963
    Jul 4, 2002
    Oh dang. My S30V samples were undersized. :( I'll have to make a new batch.
     
  17. Michael.Drinkwine

    Michael.Drinkwine KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    62
    Apr 17, 2015
    Just a quick note on steel thickness for the sample coupons. 1/8" thick stock is about the thinnest that is workable after removing decarb and accounting for warp. The finished samples need to be 2.5 mm (.0984") thick, flat, parallel, and decarb-free.

    Michael
     
    Larrin likes this.
  18. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    DevinT suggested minimum 0.120”. We got away with 0.108” before but that cut it close.
     
    Michael.Drinkwine likes this.
  19. Willie71

    Willie71 Warren J. Krywko. Part Time Knifemaker Knifemaker / Craftsman / Service Provider

    Feb 23, 2013
    This is what went to Keith Nix today. I emailed him the tracking number.

    [​IMG]9FD4D5DC-950A-4D01-834C-C42A54628769 by Wjkrywko, on Flickr

    Damn, I missed the z-wear edit. It’s 2050f austenitize.

    M4 isn’t on the list. I have two M4 samples on my bench too. I’ll throw them in the mail tomorrow,
     
    Last edited: Mar 19, 2019
    mknife, hugofeynman, daizee and 2 others like this.
  20. Keith Nix

    Keith Nix

    14
    Jan 3, 2018
    Warren, you are a hammer, an oak, a model for tenacity!
     

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