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Experimenting With Heat Treat Variables

Discussion in 'Heat Treating' started by RussGen, Jun 18, 2020.

  1. RussGen

    RussGen New Member

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    A while back I decided to concentrate on using one steel only to cut down the variables to getting a better heat treat. Being a rookie I decided on 80crv2 that I get from Aldo. I started by using Aldo's heat treat data. Many knives later they've all hardened but none are satisfactory, just somewhat hard. The steel is 1/8. I use canola oil and keep it clean and fresh. Because it took a lot of practice to get good temp control on my oil it's been all over between 110 and 150. Done many though recently with temp control at 125. Still mediocre results. Every heat treat was normalized 1650, 1500, 1350, all 10 min. Then held for 10 min. At 1500 and quenched. This is above Aldo's recommended 1465-1480. Tried his temps, tried 1500, All decarb removed, still just barely ok. Then found a post saying a lot of guys h.t. 80crv2 between 1515 and 1575. So I did the h.t. 1575 for 10 min. then into 125 degree canola. Excellant results. Am I missing something here? I'm wondering now do I work down to 1515 or try 1515 and move up. I'm excited to get this result but I know there might be things going on inside the steel. Any advise would be appreciated.
     
  2. dancom

    dancom Dust Maker Best Shop Tool

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    Good to hear you are getting better results at 1575°F. 60°F is not a lot of difference. What pyrometer/controller are you using?

    I'd stick with what is working for you.
     
  3. Griff

    Griff Active Member

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    Very interested in this, I’ve got a 3” wide x 1/4” thick 2ft bar of 80Crv2 from Aldo via Canadian Knife Maker.

    What I didn’t know was, that for a supposedly ‘simple steel’ that some very experienced knife makers on Blade Forums have had trouble getting good results with it because of, ‘large spheroidized structure.’

    https://www.bladeforums.com/threads/80crv2-chopper-heat-treat-aspects.1592499/

    This thread is very interesting on the subject.

    To be honest I’m a little pissed off with myself for not digging into 80CrV2 before just leaping into a purchase. It’s seems Aldo’s version is the trouble maker, we’re as the stuff from AKS is yielding better results. And it’s trickier using stock removal than when forging it seems. *Face Palm*

    Keep us posted @RussGen.

    My initial thoughts on all this that many have recommended an oil speed of between 11-14 seconds for 80Crv2. I’m guessing it’s actually too slow, and I am going to do a test quench in Parks 50 (7-9 sec) and in my Pro-Quench (rated 9-13 sec, with 11secs being the average) to see what results are.
     
    Last edited: Jun 18, 2020
  4. RussGen

    RussGen New Member

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    Hi guys just got back to check this before bed and am glad you responded. In answer I'm using an Evenheat Lb18 with tap controller. I'm very interested in these issues experienced by others. Maybe we can get more specifics. My guess was the canola. It's the only thing I can't control. I'm going to check back in the morning. Seems some people have had some real good results from canola. I decided on 80crv2 because I need 1/8 by 3 inch for what I do. Thanks Russ
     
  5. RussGen

    RussGen New Member

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    Hey Griff I read the link you posted and I realize there is so much I don't know so I don't want to criticize, just observe, listen and learn. Once I leave the forum I'm back to my world of gleaning info a bit at a time and experimenting. After reading the link I came away with the idea to water/oil quench after the third thermal cycle once temp. falls below 900 degrees. Bottom line is I hope there will more discussion of why this particular steel from this source responds like it does to the h.t. I used. I have no way to know what's going on inside the steel but to listen to members who are more experienced.
     
  6. dancom

    dancom Dust Maker Best Shop Tool

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    Just a side note. I've never seen any published accuracy specs from EvenHeat or Paragon. From my experience and a little research, I would guesstimate 5% is fair on average at various locations in the chamber. 5% is over 100°F at full scale. Some makers with better instruments than I have tested and have found temperature variations of 110°F from front to back of the chamber, which supports my number. Longer/larger ovens and the spread increases.

    If you are concerned about the accuracy of your setup, you can do a sanity check with a product like https://www.grainger.ca/en/product/TEMP-INDICATOR-TEMPILST1900F-1038C/p/TPL28073
    This particular Tempilstik will melt at 1038°C (1900°F) and is supposed to be accurate to +/- 1%. Place some in the middle, front and back and run a test. Optionally, you could get two the same product in two different temperature ratings. One above and one below your controller set-point. See if the lower temp product has melted and the higher temp product has not.

    I did two tests on my home-built oven. The first was Curie point test on a piece of low carbon steel. Soak a bit at 765°C and check with a magnet. It should still stick. Bump up the controller to 775°C and let it stabilize. The steel should not stick. Do this a few times and compare the numbers. The second I did was a piece of aluminum placed on a piece of scrap steel. Alum is supposed to melt at 660°C and at 660 it was just starting to puddle. None of these DIY tests will tell you down to the degree, but at least my oven was not out by 50°C or anything. I am going to be changing my probe soon. I will see if I can repeat the sanity checks and document for the group.

    Dan
     
    Last edited: Jun 19, 2020
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  7. Griff

    Griff Active Member

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    I am hoping the unique design of my oven helps even out the distribution of heat by having a set of coils in the ceiling and not just the sides. My kiln design is the precursor to Paragons new line of ovens that have sections that operate independently to ‘Even Heat’ (lol) throughout the chamber.

    But see that’s just gone and reminded me that it felt like Paragon came out with this technology the second I clicked purchase on my Double Barrel kiln haha!

    Here’s the vid on those kilns: interest tidbit, the guy in the video is Corbin Urqhart of Gameco Knife supplies in Australia and one of the hosts of the podcast Knife Making Down Under.

     
  8. RussGen

    RussGen New Member

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    Interesting angle. I've tried to change one variable at a time for control but never considered the oven. I have lots of aluminum so I will give that a try. I will place 3 small pie
    ces in front center and back. I should mention before my "succesful" hardening at 1575 I austenitized three knives at 1500. One of the knives successfuly hardened. It was 1/16 thick and soaked for the same as the other 2, ten minutes. Aldo's specs say to soak 5-15 min. before quenching. So it seems that redoing the two 1/8 thick blades at a higher temp (1575) yielded the same result as doing the 1/16 thick blade at 1500. I've always used 10 min as my soak time. Do using austenitizing temp of 1575 is ok? I'm thinking back when I used the forge I was probably out by 75 degrees on a regular basis and I did have some succeses. Anyway will test the oven and get back later. Thanks Russ
     
  9. RussGen

    RussGen New Member

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    Hey Dan, I tested my oven with 3 aluminum tokens, front middle and back and they all melted at the same rate at 1220 degrees F. Sorry, I wasn't sure how to respond directly to you so hopefully this reaches you.
     
  10. dancom

    dancom Dust Maker Best Shop Tool

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    That's a good sanity test. You can be confident that your oven is hitting the right temp. One less variable to factor in. ;)
     
  11. John Noon

    John Noon Well-Known Member

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    80Crv2 being more complex than 1084 is better however the quenching medium should still be a fast one for best results.
     
  12. Griff

    Griff Active Member

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    I reached out to Joey Atilano, he’s made a lot of big knives and swords from 80CrV2. His YouTube videos almost always show Abuse/ Cutting tests. I asked him for his Heat-Treatment regime, and it pretty much what recommend everywhere, he Normalizes 3 times, Austenitizes at 1480...

    the only difference is that without even mentioning my hunch on oil, he said “I quench in Parks 50. I think it’s more a AAA steel.” I think he just got it right and the faster oil is what is needed. His results with this steel is pretty impressive.

    His 80CrV2 is from Aldo hence the normalizing.

    AKS’s recommends for their 80CrV2

    Austenitize: Heat to 1,545°-1,615° and hold for 5 minutes. Quench in oil. (Much Higher)

    Tempering twice for two hours each time @400F should yield 60HRC.
     
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  13. RussGen

    RussGen New Member

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    Good thing for aĺl this new info, I just ordered 6 more feet of 80crv2. So Aldo faster quench. AKS more heat. What are these two places doing different with their product.What if you were to use faster oil and higher temp. Just a thought
     
  14. John Noon

    John Noon Well-Known Member

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    There is a good chance the steel from different suppliers come from the same steel mill.
    With spherodized heat treating you can have a large or a small grain. Composition and need to cold work determines this, customer can request a finer grain if desired.

    Catch being custom orders are preferred to be by the rail car
     
  15. RussGen

    RussGen New Member

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    So aks and njsb could be selling the same steel. You're saying they are the same but require different heat treats. Sorry, not really clear on the whole spherodized concept. From what you've said coarse grain is sometimes the desired result. Does that mean my austenitized knife quenched at 1575 degrees may have a coarser grain but still be a highly functional blade?
     
  16. John Noon

    John Noon Well-Known Member

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    Spherodizing is a heat treating process that leaves the carbon in little balls.
    Think of it as being between annealing and normalizing. It can be seen as the heat treatment needed for machining or grinding.

    I may look up some information about it in regards to the size of carbon spheres formed. May just need a longer soak time before a normalization cycle or quench.

    I have not looked into 1084 or 80CrV2 sources but there are not a large number of steel mills and when you get into CPM varieties there are even fewer choices.
     

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