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normalize 26c3?

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by CWendling, Dec 2, 2020.

  1. CWendling

    CWendling

    496
    Sep 10, 2005
    Bought some 26c3 from AKS for some kitchen knives, stock removal. First time using 26c3. Cut to shape, heat to 1475 10 min, P50 quench. Blade were coated with itp 64 wash and then thin rutland on it for hamon. No grinding other than to refine shape after the band saw. I dont usually normalize annealed stock for stock removal, so the question is, do you find a need to with this steel? I ask because i can count the cracked blades ive had on both hands (maybe use a foot in there). But both of the 26c3 blades had multiple cracks along the edge. No warping though. The 3 15n20 blades of the same size i did in the same batch turned out perfect.
     
  2. samuraistuart

    samuraistuart KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 21, 2006
    No need to normalize that steel. It is ready to harden as received. As a matter of fact, it is in excellent spheroidized condition. I have had excellent results using exactly the same "recipe" you did, even down to the ATP641 anti scale coating and satanite cement for hamon. Not sure why you are getting cracks when quenching in oil. You said you did no grinding at all, just profiled the blank and heat treated it? That's puzzling. I know that even if I only profiled a blade and did no grinding prior to HT, I like to have a scratch pattern of around 220 grit at the edge going lengthwise (tip to tang), and NO scratch pattern going vertical from the edge (edge to spine).
     
    SBuzek and Tom Lewis like this.
  3. Josh Rider

    Josh Rider Stuff maker Knifemaker / Craftsman / Service Provider

    Sep 2, 2014
    When you profiled, what grit belt did you use?
    Were the scratches perpendicular to the edge?
    Did you quench in anything after the p50?
    How fast did you temper after the quench and at what temp/time?
    Do you have pictures?
     
  4. imill3567

    imill3567 KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    267
    Aug 5, 2014
    I’m also curious what grit you profiled with. I’ve had only one quench crack and I’m pretty sure it was from a perpendicular 60 grit scratch. Have had no issues with 26C3 at 120grit lengthwise.
     
  5. Josh Rider

    Josh Rider Stuff maker Knifemaker / Craftsman / Service Provider

    Sep 2, 2014
    It’s possible there were small micro-fractures from the grit, like scoring a piece of glass before you break it. I’ve had it happen before with other steel. Since then I’ve kept the edges ground at higher grit parallel with the edge.
    This might not be the case without more info, just a possibility.
     
  6. CWendling

    CWendling

    496
    Sep 10, 2005
    Ill take some pics tomorrow. Cleaned up the profile with 60 then 120 grit. Edge parallel to length. Running lengthwise. However you would say it. No, full quench in room temp 70ish P50 til cool enough to hold. Went into the temper oven within maybe 5 mins. twice for 2hrs at 375.
     
  7. Pinoy Knife

    Pinoy Knife

    Aug 9, 2002
    you should have heated your oil up.. if it is too cold it can kind of thermal shock the internal structure of the steel, with all that stress built from transforming it wants to release some of it. a sacrificial bar of steel in the forge/oven going into the oil first can bring its temp up to about 150 degrees which is where ( i believe it is supposed to be used).. only my Opinion nothing else...guys forging and heat treating in water had this kind of problem. with Brine instead the problem went down considerably
    with oil even more...just the facts that i know and believe..
     
  8. Josh Rider

    Josh Rider Stuff maker Knifemaker / Craftsman / Service Provider

    Sep 2, 2014
    You don’t heat up p50, room temperature is fine.
     
    Keith Nix and DeadboxHero like this.
  9. Pinoy Knife

    Pinoy Knife

    Aug 9, 2002
    oh nevermind
     
  10. CWendling

    CWendling

    496
    Sep 10, 2005
    This was the worst. Both had a crack at the curved/choil area and a couple long cracks along edge. The big chunk came out with not much pressure (long curved crack). Grain looked good. Gyuto style chef about 9x2" blade. Cut profile on band saw, then cleaned up saw cuts just a bit with 60 and 120gr belts. Which is all ive ever done on 15n20, 1095, 01 similar blades. I forge most everything and rarely go above 120gr pre-HT. Not sayin going up to 220 wouldnt make a difference, but that just seems odd to me to have both of these cracked and none of the hundreds of other blades did. As i type this, I am now wondering if my oil was maybe a bit under 70. Ive used p50 for quite some time in the same conditions without checking temperature of oil though. Never bothered heating it as my shop is heated/ac. It was in the 40s outside, but id been runnin the heater inside at 70 for a couple days (non-stop) so room temp had been a consistent 70ish. Didnt check oil temp though.
     

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  11. Natlek

    Natlek

    Jun 9, 2015
    I have never seen something like this ......Like glass :eek: I wonder what hardness is ? Cool oil will slower cooling rate of steel . It is about viscosity . . .. .
     
    Last edited: Dec 3, 2020
    Pinoy Knife likes this.
  12. CWendling

    CWendling

    496
    Sep 10, 2005
    I didnt check hardness til after temper, but they are 62rc
     
  13. Natlek

    Natlek

    Jun 9, 2015
    I have no answers why is this happening ,sorry . But i have questions , did you try without clay/ rutland ?
     
  14. CWendling

    CWendling

    496
    Sep 10, 2005
    No. I bought the 26c3 specifically to see how the hamon performs instead of W2.
     
  15. imill3567

    imill3567 KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    267
    Aug 5, 2014
    Your process is identical to mine for 26C3 except my oil is probably closer to 60 at least for the first knife. I’ve done maybe 20 in that steel haven’t had one crack but have only clayed a couple of those.
     
  16. Skiller1nc

    Skiller1nc

    84
    Jun 27, 2016
    I can't be of much help either as I forged my 26c3 to shape thus altering the microstructure. Anyway, after quick and dirty forge normalizations(1650,1550,1450), I do a DET anneal, hold at 1445 for 30 minutes then cool at a rate of 600 degrees per hour to 1300 degrees, then I air cool. after that, I do a 15 minute total soak from the time I put them in the oven at 1430 degrees and quench into 75 degrees parks 50. All these blades are clayed, I've had no warping or cracking issues.
     
  17. samuraistuart

    samuraistuart KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 21, 2006
    Just FYI to everyone, from the Maxim oil website and tech data sheet, P50 is to be used from room temp (ambient) to 120°F. They also say, "it is as effective at 50F as it is at 120F because of its low viscosity." To those of you heating P50, keep that in mind. I would never go past 120°F. I keep mine in the garage in central TX during the summer, and pull it inside during cooler months. Notice is said "cooler", not "cool", certainly not "cold"!!! LOL! Canola oil should be warmed up to about 130°F, but not P50. Not really sure that this is a quench oil problem, tho.

    I go to 220 grit scratch pattern lengthwise, but totally agree that 120 grit is PLENTY good. The idea is to not have any scratch pattern going straight up from the edge (or spine for that matter).

    I'm curious as to exactly HOW the cracks happened. You said "not much pressure". I'll put it this way, I recall a few years ago I had a 52100 blade that took a warp immediately post quench. Normally I would run one temper cycle, then use the 3 point clamp method during the 2nd cycle to take it out. But I got big headed and decided I would see if I could just slightly bend that 52100 blade, which was about 67HRC, and it snapped in two "without much pressure". Grain structure was great! I'm suggesting that NO pressure is applied to the blade once the martensite finish has happened, which is significantly warmer than ambient with simple steels.

    Without being there and carefully noting every exact procedure, I would say you are good to go, just no more "not much pressure"!
     
    Josh Rider likes this.
  18. CWendling

    CWendling

    496
    Sep 10, 2005
    I didnt notice the cracks until after tempering. Thats then i pushed on the long crack and that whole chunk popped out. i guess i shouldve mentioned, i was pretty sure i heard a tink during the quench on one of the 26c3 blades but was hoping i didnt. I just cleaned off the oil and tempered, then saw the cracks
     
  19. Natlek

    Natlek

    Jun 9, 2015
    Josh , I read that advise many time here so i make some test long time ago with 1.2519 steel ....I grind all edge sides of pieces of steel which I prepared for test with 40 grit ceramic belt /vertical to edge / and quenched all pieces in water not in oil ,not single one cracked...But I agree that it is good to finish all edges with fine sandpaper ....cost nothing and can help :thumbsup:

     
    Last edited: Dec 5, 2020
  20. Josh Rider

    Josh Rider Stuff maker Knifemaker / Craftsman / Service Provider

    Sep 2, 2014
    I certainly don’t have any scientific knowledge to back that up, but like the op I’ve had a crack appear on steel and wondered why.
    Only after speaking with more experienced knifemakers than myself did it make sense to me.
    I wonder if @Larrin could shed some light.
    It seems like it’s a moot point anyway as the op says he removed perpendicular scratches.
     

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