3 quench vs. 3 normalization

leifjl

leifjl

Joined
Nov 27, 2011
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The only thing that'll make me a bit nervous, during the process of making a knife, is the H.T. And during the H.T. the part that makes me the most nervous is the actual quench.

So, what benefit, if any, is there in triple quenching as opposed to a triple normalization?

Normalizing seems far less stressful, to me and the steel, than quenching. Don't they both accomplish the same goal?

I was just curious and figured some of you guys with way more H.T. experience than me would have an answer.

Thanks,
Leif
 
One person in particular sells triple austenizing and quenching.


I regard it as either complete balderdash, or the first two as practice for the third.


Just my opinion,
 
12345678910 said:
One person in particular sells triple austenizing and quenching.


I regard it as either complete balderdash, or the first two as practice for the third.


Just my opinion,
Click to expand...

I learned what I know about heat treatment from non-knife sources, but I was under the impression that once a material is annealed during the ramp process or otherwise, it is basically back to square one.
 
Normalization and quenching are two different beasts. Quenching hardens the steel, while normalizing is done to reduce stress and reduce grain size in the steel. I always triple normalize but only quench ONCE! :) Normalizing comes before the quench in the HT process. Someone will chime in with a more detailed response I'm sure but that's the jist of it.
 
Leeth is correct. Quenching & normalizing are two different processes. Normalizing prepares the blade for quenching. If the steel is properly prepared then only one quench is necessary. Other people will say otherwise but like the count said its "balderdash" or just plain BS. I consider it hype to mislead people into thinking they can do mystical things with steel that other people can't.
 
I call the process that can gain the finest grain and hardest blade - Thermal Cycling.
This starts with a high end austenitization and quench or air cooling to re-form the grain and put all alloy ingredients into good solution. 1650F is a good target temp.
Next, a cycle at low end austenitization to re-refine the grain as small as possible...followed by a quench. 1450F is a good temp.
Then, a sub-critical soak and air cool to below 900F to remove all stress and prepare the blade for the final hardening quench. Water cool once the steel cools to black.
The final step is the actual austenitization and quench to harden the blade...followed by a double temper.

Triple normalizing ( heat above critical, and cool in air) accomplished the stress removal very well, but does nothing to refine the grain. This is a common practice, and does no harm. On stock removal blades, it is enough to prepare the steel for final hardening. In a forged blade, there may be more severe grain and internal condition issues that are better dealt with by Thermal Cycling.

Triple austenitization accomplishes grain refinement to various degrees, depending on the temps and hold times. It does nothing to reduce stress, and may even add some. There are those who use this method, based on one makers procedures, but I can find no metallurgical reason for it making the blade harder or superiorly finer grained. The last quench is what makes the blade hard.
 
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Ok. Thanks for the answers guys.

Specifically, I was thinking of 52100. I was under the impression that a triple normalization of 52100 will result in not only stress relief but reduction of grain size.

And the people that triple quench say they're using this process for a reduction in grain size too.
 
I'm not sure if I am reading what you say here right... In the first part of this post you run through what you call thermal cycling and say that it gives you the finest grain size.

But in the final part of this post you claim that this may induce more stress and has marginal at best grain reduction.


Is the first part a quote ? and your final part a real world answer to this quote ? No disrespect intended just wanted clarification.

I have been approaching my heat treating with three descending normalizing cycles followed by bringing the steel up to the suggested temp Quenching in Industrial quenching oil rated for the steel I am using followed by two tempers but I do water quench between tempers.









bladsmth said:
I call the process that can gain the finest grain and hardest blade - Thermal Cycling.
This starts with a high end austenitization and quench to re-form the grain and put all alloy ingredients into good solution. 1650F is a good target temp.
Next, a cycle at low end austenitization to re-refine the grain as small as possible...followed by a quench. 1350F is a good temp.
Then, a sub-critical soak and air cool to below 900F to remove all stress and prepare the blade for the final hardening quench. Water cool once the steel cools to black.
The final step is the actual austenitization and quench to harden the blade...followed by a double temper.

Triple normalizing ( heat above critical, and cool in air) accomplished the stress removal very well, but does nothing to refine the grain. This is a common practice, and does no harm. On stock removal blades, it is enough to prepare the steel for final hardening. In a forged blade, there may be more severe grain and internal condition issues that are better dealt with by Thermal Cycling.

Triple austenitization accomplishes grain refinement to various degrees, depending on the temps and hold times. It does nothing to reduce stress, and may even add some. There are those who use this method, based on one makers procedures, but I can find no metallurgical reason for it making the blade harder or superiorly finer grained. The last quench is what makes the blade hard.
Click to expand...
 
The true answer from a very reputable knife maker. This is a Must read .

http://knifetalkonline.com/smf/index.php?topic=1779.0

Again you can not compare normalizing against guenching but you should always do both and with 52100 everything should be done in threes. But thermal cycling is of better benefit then normalizing . I normalize 3, then thermal cycle 3, then anneal 3. Do all shaping and grinding, then thermal cycle 3, then guench 3.

There is very little benefit from two quenches but three will almost double your cutting ability from the first quench. Four quenches is also of no benefit.

And these were stock removal blades.

I believe any one who thinks 3 quenches is hocus pocus, has (1) never tested it, (2) did it wrong when they did test it, or (3) do not want to take that much time on there heat treat and dont want the common knife enthusiasts to know the truth, which would make the knife makers knives look bad compared to a triple quenched knife.

Just my opinion and knowledge of triple quenching. There are many other scientific and documented information about this subject.
 
leifjl said:
Ok. Thanks for the answers guys.

Specifically, I was thinking of 52100. I was under the impression that a triple normalization of 52100 will result in not only stress relief but reduction of grain size.

And the people that triple quench say they're using this process for a reduction in grain size too.
Click to expand...

Triple quenching has many benefits it produces finer grain, eliminates Almost all Ra, and gives a harder final hardness.
 
chad2 said:
Triple quenching has many benefits it produces finer grain, eliminates Almost all Ra, and gives a harder final hardness.
Click to expand...

Then please explain how I'm acheiving an as quenched hardness of 66-67 HRC with only one quench. Can you get 52100 harder than HRC 67? Also, my grain size is so fine its a bone/off white color and looks ceramic. The best way to handle RA is to never make it to begin with. If you don't make it you don't have to get rid of it.
 
chad2 said:
The true answer from a very reputable knife maker. This is a Must read .

http://knifetalkonline.com/smf/index.php?topic=1779.0

Again you can not compare normalizing against guenching but you should always do both and with 52100 everything should be done in threes. But thermal cycling is of better benefit then normalizing . I normalize 3, then thermal cycle 3, then anneal 3. Do all shaping and grinding, then thermal cycle 3, then guench 3.

There is very little benefit from two quenches but three will almost double your cutting ability from the first quench. Four quenches is also of no benefit.

And these were stock removal blades.

I believe any one who thinks 3 quenches is hocus pocus, has (1) never tested it, (2) did it wrong when they did test it, or (3) do not want to take that much time on there heat treat and dont want the common knife enthusiasts to know the truth, which would make the knife makers knives look bad compared to a triple quenched knife.

Just my opinion and knowledge of triple quenching. There are many other scientific and documented information about this subject.
Click to expand...

So the number three is magic ?

RollEyes smiley
 
I need a Rockwell hardness tester so I can do some of this testing.Sounds interesting.Darrin ,do you do the thermal cyclling like Bladesmith speaks of?
Eddie
 
You're crackin' me up Count. This has all been hashed & re-hashed. If I remember correctly there was a person who made a challenge to make a triple-quenched blade and test its performance against a single quenched blade but it never happened. I'm still up for the challenge in either 5160 or 52100. I know what my knives will do and have nothing to fear. I aint afraid to put my heat treat where my mouth is. LOL
 
Eddie, if you're talking about 52100, (Aldo's current batch) here is how I do it.
1. Heat to 1650, soak approx. 5 min., & air cool to black.
2. Heat to 1550, soak 5 min. & air cool to black.
4. Heat to 1450, soak 5 min. & air cool to balck.
5. Harden at 1480 with a 20-25 min. soak then quench.

This process consistently gives me an as quenched hardness of HRC 66-67. I then temper to the desired hardness.
 
So the triple thermal cycle is the way to go.But single quench will work.I have just started the 3 thermal cycle route with 1084 and it makes a difference as far as i can tell,I dont have a actual hardness tester,but it takes more effort to finish now.
Eddie
 
darrin sanders said:
Eddie, if you're talking about 52100, (Aldo's current batch) here is how I do it.
1. Heat to 1650, soak approx. 5 min., & air cool to black.
2. Heat to 1550, soak 5 min. & air cool to black.
4. Heat to 1450, soak 5 min. & air cool to balck.
5. Harden at 1480 with a 20-25 min. soak then quench.

This process consistently gives me an as quenched hardness of HRC 66-67. I then temper to the desired hardness.
Click to expand...

This is the exact same schedule I use for 52100 also.
And I just bought a hardness tester last week, so I know I'm getting 65-66.
What quenchant are you using, if you don't mind me asking?
 
Marko3 said:
I'm not sure if I am reading what you say here right... In the first part of this post you run through what you call thermal cycling and say that it gives you the finest grain size.

But in the final part of this post you claim that this may induce more stress and has marginal at best grain reduction.


Is the first part a quote ? and your final part a real world answer to this quote ? No disrespect intended just wanted clarification.

I have been approaching my heat treating with three descending normalizing cycles followed by bringing the steel up to the suggested temp Quenching in Industrial quenching oil rated for the steel I am using followed by two tempers but I do water quench between tempers.
Click to expand...



The first part is a standard thermal cycling procedure, which I use. It starts with two descending temperature quenches, and ends with a normalization. After that procedure the steel is ready for the final quench.

Triple normalizing, with descending heats will accomplish excellent stress relief, but won't refine the grain. It is a good procedure for stock removal, where the grain size is normally already fine. The procedure you use will give you good results, and is metallurgically sound.
However, if you forge, the multiple quenches in thermal cycling will refine the grain that may have grown during all the heats. Not doing it won't mess up a blade, but the final grain may be a bit less fine.

My last comment was about using three hardening quenches in a row. This may induce stress, and unless the temps are dropped at each quench, won't reduce grain appreciably beyond the first hardening. My problem with this system isn't the system itself, but the claims of extraordinary grain refinement and higher hardness. Those who want to use this system will make a fine knife if they hit the HT right, but the last quench is the only one that will matter. The long and short of it is that this method will make a good knife...but there is no magic in the procedure.





From the Moderator:
This is an old discussion, with strong opinions on both sides. I will drop it as for myself, now. Those who wish to continue the discussion feel free to do so, but keep it civil. Many of these threads end up being locked.
 
Stacy, at what point following the high end (1650) austenization do you quench?




bladsmth said:
I call the process that can gain the finest grain and hardest blade - Thermal Cycling.
This starts with a high end austenitization and quench to re-form the grain and put all alloy ingredients into good solution. 1650F is a good target temp.
Click to expand...
 
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