52100 heat treat??

J

Johnbeck180

Joined
May 16, 2011
Messages
199
Ok, got this knife done about a week ago. It seems to hold an edge very well. It's made from 52100. When I was making this knife I decided to leave the whole knife a little thick, as you can see from the pic the edge is somewhat large due to the angel of the edge grind. I bought the steel from Aldo Bruno, it was very easy to work with as it came to me in the annealed state. I did all the grinding without gloves to prevent the steel from heating up to much. I then did three normalizing cycles. My normalizing was done by placing the knife in my forge and then heating till non mag then letting color go dark. I then heated till non mag and quenched in Parks 50. I had the oven pre-heated to 400-425 and immediately put the knife in the oven for approximately 1hour and 15 min drawling it back to a medium/dark straw. Is my heat treat process right for 52100? Thanks. :0)
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Non-magnetic is not hot enough for 52100, and p50 is too fast for the quench.

You probably hardened it to a degree, but no where near the full capability of the steel.
 
What would you suggest doing at this point? I can easily take the Handel material off and quench again at a higher temp, I also have used motor oil and I can easily make a brine solution for a possible quench.

Thanks.
 
I would leave this knife as is, and do some research on the HT for 52100 before doing the next knife. Canola oil will work for 52100, and the temps and procedures are well discussed.
The normal cycling procedures to refine the grain are used. 1650F - quench, 1450F - quench, and 1250F - air cool to black, then quench...... are good temps for the three steps.
The hardening is done with a 15 minute soak at 1475-1550F, followed by a quench in canola or medium speed quenchant.
Tempering is usually around 400-425F for two hours, twice.

Here is part of my text from a former thread of this:
Here is the search engine to use in researching a subject.
http://www.google.com/cse/home?cx=01...:qfobr3dlcra

Here is a very extensive discussion on the HT of the three main steel categories:
http://www.bladeforums.com/forums/sh...ee-steel-types

52100 is one of those steels that gets a lot of discussion. It can make a great knife, but the HT for it is not simple. It can make an OK knife with simpler procedures.
I will tell you the metallurgical way to do the HT for 52100:
The steel has 1% carbon and 1.4% chromium. This means that it is hyper-eutectoid steel with a fair amount of alloy to form chromium carbides. You will have to do the HT in such a way as to allow those elements to form the proper structures. To do this you will need a HT oven or forge that can be held at a controlled temperature for ten minutes, and a quench oil that will harden the blade. The oil should be a medium speed commercial quench oil, but Canola will do if nothing else is available. Forget about motor oil and ATF, etc.

Forging - Forge 52100 HOT. It is forged between 1700°F and 2100°F, and should not be forged in the lower red colors.
Normalize ( stress relieve) - Heat to 1650°F and air cool.
Annealing is tricky for 52100. The best way without really good equipment is to do a sub-critical anneal. Heat to 1250°F and cool to black. Then quench in oil. Do this a couple times.
Cycling the steel - This is one of the Triple Treatments often mentioned with 52100. It will get the steel ready for its final hardness and produce a fine grain. Start by heating the steel to 1650°F and quench in oil. Re-heat to 1350°F and quench in oil. Heat again to 1250° and cool to black, then quench in oil. Now the steel is ready to harden.
Hardening - Heat the steel to 1500-1525°F and hold for ten minutes. Quench in oil.
Tempering - Immediately temper at 400-450°F for two hours, cool in running water, and repeat the temper.
Cryo/Sub-zero treatment - 52100 can gain from cryo if you have the ability. Do a snap temper at 300°F and them immerse in a sub-zero bath at
-100° or in LN at -325°F. (An overnight stay in the home freezer won't do anything metallurgically.) After the sub-zero/cryo bath, temper as normal.
 
Stacy, thank you for the great info. I new I should of asked about it first..lesson learned. I did do some research on it, but almost every recipe I read was different from the last :0) the last one I remember reading said just to heat treat it like 10 series steel.

Do you think it's hardened at all? What is a good way to test the edge hold ability of a smaller knife? The good thing is with your info the next one will be better. :0)

Thanks a bunch!
 
It is probably hard enough to use. The test is to sharpen it and cut some stuff....wood, cardboard, sisal rope. Look at the edge, is it chopped, rolled over, dull and rounded? If it appears OK, and the knife cut well enough, it is good to go. You will see the difference in this HT and a good 52100 HT when you do the next one and compare the two. 52100 can get screaming sharp, and will get quite hard. the HT regimen listed should give you a blade around Rc60.
 
Great follow-up Stacy. Thanl you. That would take me an hour to type, and not be as complete.

Nice style knife Johnbeck. Just wait 'till you see your next one. :thumbup::thumbup::)
 
That's what I've been doing for the past 30 minutes. So far I've mangled a valvoline oil cardboard box made around 75 cuts in the box. I would jam the knife in the box and run it from one end of the box to the other while pulling the blade out so the whole blade cuts the cardboard. Also cut quite a few small branches about 3/4 - 1 inch in diameter off a tree. Ill continue to use the knife through out the day. It's still very sharp. Can't wait to make the next one.
 
Stacy, from what I've read about steels and cryo, doing a snap temper before cryo would seem to be counterproductive- the goal being to reduce retained austenite, in which case cooling should proceed from quench, right down to the low point of cryo.

Your thoughts?

Also, although I no longer triple quench from critical, I understand that the thinking behind this is that it can enhance full austenitization when the ability to soak is marginal. What I have read is that the best structure to form martensite from is a previously martensitic structure. Thoughts on that?

Feel free not to respond to the above if you think it will start another exhaustingly redundant thread about triple quench and grain size in 52100...
 
No problem:
The 30 minute snap temper at 300 is an industry standard that prevents possible cracking. It is low enough and short enough not to stabilize any significant amount of RA.

The sub-critical step in a triple cycle pre-HT could well be done at 1350. However, most folks doing it are using a magnet, and the sub-critical step assures the final structure to be reliable. If one was shooting for the max in grain refinement, the three step pre-HT could be followed by a double HT quench. This would re-form the structure as fine grained martensite, and then re-form it again with the max in distribution of alloys and fine grain. Probably overkill, though.
 
Thanks Dewey, sorry didn't see your post. Ok so far I've demolished the cardboard box, cut a couple bottle caps in half, cut some rope by push cut and slicing, cut a three foot rubber hose up into 1-2 inch sections, cut some branches off trees, cut about a ton of paper, shaved some plastic off a Rubbermaid trash can, cut myself, and whittled wood. It has lost it's shaving edge but I can still take it through paper very easy. It will take some hair off but not like a razor would.
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It still curls wood on all spots on the blade
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I will continue cutting things and post back later.
 
Given how well your knife cuts now, just imagine how well your next one will cut with a better HT!

- Chris
 
I know!! :0) that's exactly what I've been thinking. All together I probably made around 300-400 cuts. I am very surprised and pleased at the edge it kept. I didn't get to cut anything else because we got busy. Any who thanks for looking guys, and Stacy, again thank you for the great info ill be jotting a lot of notes in my notebook tonight :0)
 
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