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Shop Error - accidently HT 52100 with simple 1084 methods........Advice Needed
- Thread starter Steelhog
- Start date
If you’re saying that all of those things are important for an optimal heat treat then using a forge to heat treat sounds even more ridiculous.
Hoss
Like I said, if the blade is tested and everything checks out, then the customer is still getting a quality product even if a kiln wasn’t used. Even if I did use a kiln, I would still test the blades anyway.
Alex Topfer
Gold Member
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- May 1, 2019
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- 746
They are necessary for an optimal heat treat, but not important for a functional heat treat. But if you're going to chase optimal you better control every
variable.
At some point in designing something you have to decide the tolerance you are working to. Chasing the absolute smallest tolerances is unnecessary and, IMO, boring.
I wouldn't heat treat a sporting rapier blade in a forge, but a kitchen knife is a different design. A forge heat treated kitchen knife by someone who knows what they are doing and has tested it is fine (once again, in my opinion).
Talking about optimal and perfect is a waste of time.
Steelhog may as well test their knife and see how well it works. They may even decide that a forge based heat treat for 52100 meets their goals.
The higher the alloy content in a steel, the harder it is to get a good heat treatment using a forge.
Hoss
DeadboxHero
Knifemaker / Craftsman / Service Provider
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I disagree Alex, just sounds like bad advice.
Also, I feel the opposite when it comes to swords versus kitchen knives, there's more people that use kitchen knives professionally then sport rapiers which are dull and not as demanding on edge stability and edge performance.
The advice from Devin Thomas is solid.
I know his answers are terse and perhaps people don't know Devin's history, he has been doing this for longer than most of us have been alive. He was a pioneer in the early days of high performance kitchen knives, steels and heat treatment before the custom kitchen knife world blew up. He still makes one of the finest, high performance kitchen knives people can get their hands on.
So, we got advice given from someone saying that mediocre is okay and someone who makes some of the best performing knives in the world.
Guess folks will have to pick and choose what they want to make.
In my opinion, life is too short to be mediocre. It'd be cheaper to just buy the knife blanks from overseas if mediocre is the goal
- Joined
- Jul 2, 2009
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- 1,176
Hey thanks all for the feedback and discussion. Definitely not at the point where I am selling anything - this is just for fun and learning. The one area I am still a bit unclear on is what the attributes of the improperly HT 52100 blade likely are. Would it be more brittle, too soft, be too hard or just not as good as it could be? Would it be worse than 1084 or just not as good as 52100 has the potential to be? I will test is no matter what but wondering what your thoughts are.
And almost all knife maker still use toaster oven for temper .................very scientifically
- Joined
- Aug 9, 2002
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- 1,335
well guys let me just give my "Opinion" (Yea no one asked little ol me for it)
Devin Thomas made and commercially built and sold more "High Carbon" AND Stainless Damascus than most everyone here could Dream of owning..
i Have known him and watched his son Larrin both come up in the "Knife World" for the last 25 plus years..
He Does know his shit !!!!
i think a very common problem is many "Knifemakers" want to do Everything as cheaply as possible... i build a forge out of a old coffee can and propane torch, using half a bag of cement to line it..
Devin / Larrin are BOTH Professionals their advise is "How to get the MOST out of it , not the minimum of acceptable..
if we as "Knifemakers " are to grow our "Craft" we need to either come up with our own formulas/ recipes for Metallurgy, or follow those that are Metallurgists like Larrin/Devin .
Wayne Goddard used to heat treat blades in his own formula of "Goop" he developed ways to make things work with "HIS formula..
the big problem i see is the "New Guys" watching FIF and thinking they are a overnight "Expert" then trying to "School" the old guys that have done this most of their life...
Ed Fowler was the "King" of 52100 steel back in the day but since very few ever got to learn "ED's" method of heat treating /grain refinements few know how to get the BEST results out of it .
Did he harden the blade ? yes. he asked if he might have messed it up? and if he did how to fix it?
Devin Thomas made and commercially built and sold more "High Carbon" AND Stainless Damascus than most everyone here could Dream of owning..
i Have known him and watched his son Larrin both come up in the "Knife World" for the last 25 plus years..
He Does know his shit !!!!
i think a very common problem is many "Knifemakers" want to do Everything as cheaply as possible... i build a forge out of a old coffee can and propane torch, using half a bag of cement to line it..
Devin / Larrin are BOTH Professionals their advise is "How to get the MOST out of it , not the minimum of acceptable..
if we as "Knifemakers " are to grow our "Craft" we need to either come up with our own formulas/ recipes for Metallurgy, or follow those that are Metallurgists like Larrin/Devin .
Wayne Goddard used to heat treat blades in his own formula of "Goop" he developed ways to make things work with "HIS formula..
the big problem i see is the "New Guys" watching FIF and thinking they are a overnight "Expert" then trying to "School" the old guys that have done this most of their life...
Ed Fowler was the "King" of 52100 steel back in the day but since very few ever got to learn "ED's" method of heat treating /grain refinements few know how to get the BEST results out of it .
Did he harden the blade ? yes. he asked if he might have messed it up? and if he did how to fix it?
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- 1,176
Ok. I put an edge on it and did a few tests. Dropped it on the concrete floor, pounded it through some knotted wood, cut some cardboard and hammered it through some brass rod a few times. The brass rod did some minor damage but it would sharpen out no problem. Edge still shaves. What would one expect to see doing this type of testing?
- Joined
- Dec 10, 2016
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- 199
I would not expect any repeatable, broadly acceptable results from that type of testing. Those tests are only relevant to you. What I would expect from 52100 that only made around 1450F or so with no soak is a pretty significant drop in RC. If it's "hard" it'll be a good reference point for when you get one that is HT correctly. It's probably better than 52100 that was over heated.
DeadboxHero
Knifemaker / Craftsman / Service Provider
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*Gives Natlek a big hug
You're going to be okay, You are a part of the knife community and surrounded by people that also like knives as much as you.
I believe in you, that you can continue to co-exist with different methods and opinions.
*Gives another hug
- Joined
- Jan 11, 2019
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- 1,484
By now you have learned that you don't have optimal HT for the steel. Does it mean it won't perform at all? No. Does it mean it will perform as it would if it had an optimal HT? No. Does it mean it is unusable because of it? No.
Sharpen it again to shaving sharp and cut through a 2x4. Do 400-500 wacks against a wooden plank and see how it performs after that? Does it steel shave hairs? How does the edge look?
If you keep it for yourself and experiment I see no harm in finishing out the blade. It is all part of the learning curve. You will get to hand sand and finish out a handle. Compare the knife to something that you might have bought in the shop for an average sum. It might still be much better.
We have the luxury of having some of the finest people in the industry posting on BF and share their time and knowledge with us hobbyists. For this we can only be thankful. It is good to know as much as possible and apply it to the equipment and stage of skill and knowledge we currently have. No harm in not applying it if not possible ATM, but be aware of not doing the best possible job. It doesn't mean you shouldn't learn by doing with the equipment and skill you currently have.
Steel in the annealed condition has twice the volume of carbide as it does in the hardened condition. During austenitizing smaller carbides dissolve and the carbon and alloy go into solution to strengthen the matrix during the quench.
52100 requires longer soak times to dissolve enough carbides.
Sufficient soak time at the correct temperature + parks 50 quench + cryo + double temper and you’ll have a good knife.
Hoss
52100 requires longer soak times to dissolve enough carbides.
Sufficient soak time at the correct temperature + parks 50 quench + cryo + double temper and you’ll have a good knife.
Hoss
DeadboxHero
Knifemaker / Craftsman / Service Provider
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Some words of encouragement, good job asking questions and going out and testing stuff I think you'll like where that can take you.
- Joined
- Jan 3, 2018
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- 226
If my well insulated, convection fan, PID controlled toaster oven holds +-1°C anywhere in the box as measured by a certified thermocouple, that's "scientifically" enough for me.
- Joined
- Jan 3, 2018
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- 226
I'm mostly a lurker here, and I'm very grateful for the knowledge I receive. My observations have led me to believe there are several kinds of people on this forum.
Real experts- Devin Thomas is one of those. There are others, and if you read enough threads, the cream rises.
Very knowledgeable people- These folks don't know everything, and they know they don't. Even though they are strong knifemakers, they're always seeking knowledge.
Newer makers with limited experience- Mostly a respectful and respectable group, looking for solutions to problems from folks who have a bit more experience.
Self proclaimed experts- Well, you know how that works out.
Newbies- Mostly here to receive knowledge. But there are a few who just can't believe that uncle Bobby's torch hardened D2 knives aren't the best thing since fermented barley and hops. And they contest the experts, not knowing who the hell they're talking to. It never ends well.
I never want BBQ that is "good enough". I seek perfection every time I fire my smoker. I bought a dewar and keep it charged with LN2 because the data says that cryo improves the properties I find important in a knife. I use a PID controlled furnace and tempering oven, because time and temperature matters when it comes to optimizing performance, as does edge geometry.
If someone else wants to heat steel to red hot in a pine knot fire inside a cinder block, well ok. Just don't try to pass that off as an optimal heat treat.
Real experts- Devin Thomas is one of those. There are others, and if you read enough threads, the cream rises.
Very knowledgeable people- These folks don't know everything, and they know they don't. Even though they are strong knifemakers, they're always seeking knowledge.
Newer makers with limited experience- Mostly a respectful and respectable group, looking for solutions to problems from folks who have a bit more experience.
Self proclaimed experts- Well, you know how that works out.
Newbies- Mostly here to receive knowledge. But there are a few who just can't believe that uncle Bobby's torch hardened D2 knives aren't the best thing since fermented barley and hops. And they contest the experts, not knowing who the hell they're talking to. It never ends well.
I never want BBQ that is "good enough". I seek perfection every time I fire my smoker. I bought a dewar and keep it charged with LN2 because the data says that cryo improves the properties I find important in a knife. I use a PID controlled furnace and tempering oven, because time and temperature matters when it comes to optimizing performance, as does edge geometry.
If someone else wants to heat steel to red hot in a pine knot fire inside a cinder block, well ok. Just don't try to pass that off as an optimal heat treat.
DeadboxHero
Knifemaker / Craftsman / Service Provider
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- 5,383
Well, because it's the austenitizing temperatures that are controlling the majority of the mechanical properties of the steel, not just the temper which gets all the glory for "muh toughness" and "muh hardness"
It is oversimplified by folks that the tempering tempetures and rockwell hardness are controlling all the mechanical properties and that all folks are doing during the heat up before quench (austenitizing) are avoiding grain growth.
This is incorrect.
For a steel like 52100 and 1095 that have high amounts of carbon with simple iron carbides it's very easy to dissolve too much carbon or not enough carbon to get the ideal properties.
Or not fully austenitize the 52100 which needs more soak time than 1095
We'll look at Dr Verhoevens work in his book
"Metallurgy of Steel for Bladesmiths & Others
who Heat Treat and Forge Steel" 2005
Steel Metallurgy for the Non-Metallurgist: J. D. Verhoeven: 9780871708588: Amazon.com: Books
Steel Metallurgy for the Non-Metallurgist [J. D. Verhoeven] on Amazon.com. *FREE* shipping on qualifying offers. Steel Metallurgy for the Non-Metallurgist
www.amazon.com
First,
There are different types of martensite that are formed based on how much carbon is dissolved into the Austenite when heating before quench.
Lath Martensite and more brittle Plate Martensite
Also too much carbon in solution leads to a high volume of austenite that is retained after quenching which didn't convert to martensite. (Retained Austenite/RA)
Meaning, you can a knife that's both soft and brittle from putting too much carbon in solution.
So, carbon control is key and it's controlled by time and temperature.
Plate Martensite is slightly harder, but during its formation can form cracks in the martensite.
There is no real big increase in hardness putting more than 0.6%wt carbon in solution. (At least not anything worth the tradeoffs described above)
Leftover carbon thats not in solution is in the Carbides promoting wear and strength.
.
Another diagram showing the hardness curves of carbon % wt in solution.
The effect of retained austenite, it is hidden from HRC testing, at the same HRC, higher %RA reduced yield strength meaning that two knives at the same HRC, the higher RA blade will roll at the edge and bend plastically easier.
Meaning lower edge stability at same hardness.
(Also the RA can convert under stress to brittle untempered martensite in the blade)
RA=Bad
(Diagram from Knifesteelnerds https://knifesteelnerds.com/2018/11/12/rockwell-hardness/)
The simple high carbon steels like 1095 and 52100, it should be avoided putting too much carbon in solution which is very easy to do especially without temperature control.
Diagram showing hardness dropping as more carbide is dissolved putting more carbon in solution and making more retained austenite after quenching.
Meaning the blade will be soft and brittle regardless of how it's tempered after.
High carbon simple steels need to be Austenitized in the two phase region between A1 and Acm. The iron carbon phase diagram below showing visual representation of what the "two phase region" is from the graph above.
(This Diagram shows carbides in grain boundaries but more accurately and pertinent to knives we see finely dispersed spheres of carbides.)
Blue line added to show the desired austenitizing range for 1095 type steel the "sweet spot" is a point on that blue line, the goal is not to dissolve all the carbides. Which means temperature control is king
*This is different than lower carbon steels (on the left in diagram) which need to be fully austenitized to single phase so that no ferrite is left over.
More detailed diagram showing the fine spherodal carbides in the austenite grains. When the austenite is quenched and transformed to martensite and tempered these small sphere like carbides will still remain and will promote more strength and wear resistance. Each little carbide in a simple steel like 1095 is in the range of ~70hrc
Diagram showing the need for a longer soak time for 52100 over a plain carbon steel with similar carbon content at the same temperature to get the same amount of carbon %wt in solution with the austenite due to the effects of the chromium alloy added to 52100.
Conclusion of why you shouldn't HT in a forge.
1.Not able to control time and temperature effectively
*Meaning not able to produce most desirable mechanical properties of a low plate martensite, low retained austinite and fully austenitized microstructure with a nice balance of primary carbides as described above.
2. Less repeatability, more variation in results meaning success can be more by accident.
Meaning problems may occur with lower performance that may not be the fault of the steel, problems will be difficult to rule out as the steel itself due to scatter in temperatures used. For instance if Person A says "1095 is too brittle" and is using a forge with no temperature control need to rule out operator error due to bad control.
3. Steel not unlocked to full potential.
Meaning it will be the name of the steel but not what it's truly capable of in performance. If passionate about higher performance more control is need then eyeballing in a forge.
4. A Magnet is not a substitute for temperature control.
The "curie point" (break down of Magnet domains) is not the same as the "Ac1"(austenite formation during heating) on the iron carbon phase diagram. Also, given that carbon has to be even more carefully controlled for higher carbon steels
The old saying of "go a little past non magnetic" isn't going to work consistently for best results.
Steels like 52100 and 1095 have a sweet spot in the two phase region between A1 and Acm meaning without temperature and time control there's no control over the details that are really controlling mechanical features that give the best performance.
Can You Trust Your Magnet During Heat Treating? - Knife Steel Nerds
Many knifemakers heat treat with nothing but a forge and a magnet. Is that reliable? What does it mean when the steel is no longer magnetic?
knifesteelnerds.com
Also, this book is easier to get more understanding of these complex topics than Dr Verhoevens, yet also has some details and useful reference tables that can be used real world. Both excellent books, they feed each other and make the brain "buzz"
Amazon - Knife Engineering: Steel, Heat Treating, and Geometry: Thomas, Dr. Larrin: 9798621848873: Books
Knife Engineering: Steel, Heat Treating, and Geometry [Thomas, Dr. Larrin] on Amazon.com. *FREE* shipping on qualifying offers. Knife Engineering: Steel, Heat Treating, and Geometry
www.amazon.com
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Congratulations. You started a small uprising. Just enjoy it it doesn't happen very often now. D DevinT doesn't take the time to make sure that you feel good about things but it is good info. He also took the time to say that new people coming in is a good thing. I don't think he believes that doing something in a less than optimal way is worth the time if there are other options. Just take what was said and don't read anything into it.
It looks like you are to far along to heat treat a second time so now you can see what happens when you do it that way. It might be pretty good. I'm not good at using forge but i used one for awhile and the knives work well and the people that I gave them to all like them as well. Most people have crap knives and anything is better. When you want to make your ultimate knife it's pretty awesome that it isn't hard to find info about what to use and how to do it. What matters now is that you are enjoying the learning process.even if this blade isn't great you are going to learn a lot. Enjoy the fireworks.
Just to start more...If you know how to make a better blade and don't you should be able to admit that it isn't the best way to do something. You can have reasons like not having the equipment but it doesn't change the fact that you could have done it better. I have a forge and don't use it often because I'm not good at it but when I do I know that I could have done better. I also know that my best isn't THE, best. So long as a person knows and is honest about things they should just keep on doing what they want.