3 quench vs. 3 normalization

Bluntcut I have used some of aldo's 52100 3/32" stuff for a few kitchen knives and what not. I use my forge to HT with, it holds decent temps but no where near the ability of a kiln or salt baths obviously. I used parks 50 for my quench. Before I made any keeper blades I broke several blade shaped objects to see grain size with the naked eye.

I got several blade objects to look like your last picture with a couple normalization cycles followed by a single quench. Or atleast close. The ones above it that you posted (top one) looked more like some 1084 I heated to high or some 1095 that I didnt cycle then heated the end of the blade to high.

I think Aldo's 52100 is pretty fine grained as it is so as long as you dont do too much to it then you can hang on to that pretty well. I have not played much with his thicker stuff yet.
 
quint said:
Bluntcut I have used some of aldo's 52100 3/32" stuff for a few kitchen knives and what not. I use my forge to HT with, it holds decent temps but no where near the ability of a kiln or salt baths obviously. I used parks 50 for my quench. Before I made any keeper blades I broke several blade shaped objects to see grain size with the naked eye.

I got several blade objects to look like your last picture with a couple normalization cycles followed by a single quench. Or atleast close. The ones above it that you posted (top one) looked more like some 1084 I heated to high or some 1095 that I didnt cycle then heated the end of the blade to high.

I think Aldo's 52100 is pretty fine grained as it is so as long as you dont do too much to it then you can hang on to that pretty well. I have not played much with his thicker stuff yet.
Click to expand...

Thanks for the insight, Quint!

I made a petty with 1 norm (1650F) > 1 quench(1525F) > 2 temper(400F), it has fine grain (not as fine as my last pic) however edge retention is sub-par and too soft(maybe 59rc). And then made another knife with same problem. Frustration -> lead me to experiments with triple norm+quench; freezer; sub-zero. I've access to LN2 but yet to experiment with. I like to keep ht simple because there are too much room for errors (mainly warp) in complicated & lengthy ht processes.

Here is a 62rc fixed blade didn't survived my batoning test, broken a few days ago. Perhaps a crack was propagated from the inclusion. I expected chips (from high hardness) but broken into 2 pieces was unpleasant because I really like this knife with purple-heart handle. Complicated ht, grain seem fine but I had to peened at least 300 strikes to warm straighten this darn seriously warped blade. Oh well, will make more 52100 knives later with heavy wariness about warpage from complicated ht.
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When looking for the right temperatures, grain size, and heat treat in a steel like 5160 / 52100. I suggest you find the right temperature for YOUR! Kiln and your piece of bar stock, because the difference in steel composition varys a lot and the difference in kilns varys also.

My suggestion to any one who is trying to find the best heat treat for there set up is take a couple pieces of steel from the bar you are goung to be using and heat one at 1425 for about 5 mins to 10 mins depending on steel thickness, for 1/4 in steel I soak my blades for 7 mins , this ensures the spin comes completely to heat. Quench in your oil of choice and test for hardness. Raise the temp 15 degrees each time until you get your desired hardness at the lowest temp possible. Keep in mind that each time you raise the temp you should let your kiln cycle for 30 mins.

At this point of desired hardness break the piece of steel and check the grain. Raise the temp 10 degrees and check again do this until you notice grain growth. When you have found the right temp.

This is when you can start experimenting with multiple quenches. And any other types of cycles that have been talked about here. After each new step that you incorporate break the piece again comparing to the others.

You will find the right heat treat for your set up that gives you your desire in grain size and hardness. And by the end of this process you will be much more comfortable with heat treating also you will know with out a doubt what kind of knife you are making.

This is when I started testing edge retention and toughness. This is how I came to the conclusion for my heat treat. It works for me. But it may not work for you so I encurage testing.

Through testing is the only way to prove that what ever you are doing works.

Strive on my friends!
 
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We are straying off topic. The OP wanted to discuss 3Norm. vs. 3quen. I use a combination of both that is easily accomplished in under an hour, as opposed to several days.

I triple normalize(after forging) at decreasing temperatures with a quench on the last two cycles. My final step is to sub-critical anneal(redneck spheroidize). When using simple steels like 10xx, 5160 and 52100, I heat it a few times until the colour just begins to appear and let it cool in still air. With a steel like L6(RDS), I run a program in my kiln that soaks at 1250F for 4hrs, then ramps down 100F/hr to 800F, where it is then removed from the kiln to cool in still air.

I choose to sub-critical anneal or spheroidize from a fully martensitic state(or as close as I can get:)). I would probably screw up the metallurgical reasons for this, so I won't attempt to explain. Forgive me.:o

I don't subscribe to low temperature forging, drawn out normalizing cycles, commercial freezer treatments, consecutive final quenches or the like. Much of this directly contradicts what we know as metallurgical fact. Some would see this as "cutting edge" pioneering work and compare these individuals to the rebel scholars who challenged the common acceptance of the Earth being flat... the majority see things in a different light. Don't fool yourself into thinking there is serious controversy in the scientific community over this. Either way it turns out, I only hope we can finally put the argument to rest and carry on with reality.
 
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Are there reference images & ht recipes for 52100 optimal grain size for various kind of usage? Yeah, good to have target to stride forth. I would like knives that performance well in spheroidal & flat & dellusional earth...
 
I just tried a 52100 blade HT last week. I did a triple normalization without quenches, 1600, 1450, 1200 then 1475 for 10 min, quenched in Maxim DT48, 400f temper. The tip didn't harden, and could be bent over with my thumb. I was more worried about overheating rather than underheating the tip, and the color going into quench was uniform. Redid the 1475 for 10 min, into the Maxim again, made sure it was at room temp, then stuck it in the freezer overnight. Tip is now hard. I "think" I didn't quench long enough the first time, and the heat retained in the blade left the tip soft, and going into temper without fully reaching full hardening, added to the problem. At that point the tempering colors were all over the map. With the freezer cycle between the quench and temper, the temper colors were quite uniform. What do the more knowledgeable people think happened?
 
Karl B. Andersen said:
Stacy, at what point following the high end (1650) austenization do you quench?
Click to expand...

1650F and quench to reset the grain
1350 and quench to refine the grain
1250F and cool to black, then water quench to room temp. This stress relieves the steel.
Target temp (1475F for example) and quench to below 900F where I inspect and straighten the blade. Then place back in the oil to cool to ambient temp.
Two tempers at the desired temper ( 400F for example), two hours each, with a water quench between them.
 
Willie71 said:
I just tried a 52100 blade HT last week. I did a triple normalization without quenches, 1600, 1450, 1200 then 1475 for 10 min, quenched in Maxim DT48, 400f temper. The tip didn't harden, and could be bent over with my thumb. I was more worried about overheating rather than underheating the tip, and the color going into quench was uniform. Redid the 1475 for 10 min, into the Maxim again, made sure it was at room temp, then stuck it in the freezer overnight. Tip is now hard. I "think" I didn't quench long enough the first time, and the heat retained in the blade left the tip soft, and going into temper without fully reaching full hardening, added to the problem. At that point the tempering colors were all over the map. With the freezer cycle between the quench and temper, the temper colors were quite uniform. What do the more knowledgeable people think happened?
Click to expand...

you may want to bring your heat up just slightly like around 1485-1495 range and see how that works. also you should keep the blade in the quenchant for at least a min if not two mins.

also this really does not make sense to me because 52100 will actually air harden to around low to mid 50's hrc. so i would think there was something definantly done wrong the first time around
 
I know there is some debate on the freezing of carbon steels, but I was reading through the Verhoeven book, and thought this might be part of the difficulty with the reported inconsistencies with 52100 HT. It seems to me it is fairly easy to hit the MS with 52100, but getting the MF may be more of a challenge. The first HT definitely went wrong. For reference I have 5 gallons of quench oil. On the first attempt I used an interrupted quench as I was worried re the Maxim oil being too fast and stressing the steel. I held it in the oil for at least a minute on the second attempt.
 
I really did read it all the first time, but it just seemed like there was something missing.

OK - so you're coming out of your heat source at a full 1650 and quenching with it that hot?
You do not let it cool down a bit first?
And you're letting it do a full martensite conversion from that temp/quench before you put it back in to ramp up to 1350?

Thanks, Stacy.


bladsmth said:
1650F and quench to reset the grain
1350 and quench to refine the grain
1250F and cool to black, then water quench to room temp. This stress relieves the steel.
Target temp (1475F for example) and quench to below 900F where I inspect and straighten the blade. Then place back in the oil to cool to ambient temp.
Two tempers at the desired temper ( 400F for example), two hours each, with a water quench between them.
Click to expand...
 
In case you hadn't guessed, you stepped into a hornets nest! As a newer maker, I was all set to triple quench, cycle in the freezer, etc during my first hardening attempt. Mostly from reading the mag that shares a name with this forum, nothing like a secret/special method for someone new to a process. The man who writes those articles is highly respected and deserves that respect. Luckily I realized my steel was different from his and the methods only applied to the 5xxxxx series before I made any forum posts.

Many have been able to duplicate his results, many more have not. From what I can tell, the science may support further grain reduction from a triple quench but it can't fully explain the reported benefits of the triple quench process. Benefits that some very respected folks have been unable to reproduce. Only time will tell, maybe science will catch up and end the controversy.

In the meantime, I plan on trying the triple quench only after I have a repeatable single quench process for 5150/52100. I will make up my own mind then. And that may never happen, I am having too much fun with hamons to stray away from shallow hardening steels.

For the record, we owe the man who writes those articles a debt. He was and is a pioneer in our craft and has freely shared his knowledge and advanced the art of knifemaking. That said, he is repeatedly pushing a controversial heat treatment regime as accepted practice in media where beginners pick up on it and apply it inappropriately. He could be more clear in the articles that his methods and results apply only to the steals he uses and should be attempted only after a standard heat treat has been mastered. This new maker confusion causes stress to other forum contributors who are constantly having to correct the missunderstandings of beginners when they turn to a forum for help.
 
BFrancios said:
In case you hadn't guessed, you stepped into a hornets nest! As a newer maker, I was all set to triple quench, cycle in the freezer, etc during my first hardening attempt. Mostly from reading the mag that shares a name with this forum, nothing like a secret/special method for someone new to a process. The man who writes those articles is highly respected and deserves that respect. Luckily I realized my steel was different from his and the methods only applied to the 5xxxxx series before I made any forum posts.

Many have been able to duplicate his results, many more have not. From what I can tell, the science may support further grain reduction from a triple quench but it can't fully explain the reported benefits of the triple quench process. Benefits that some very respected folks have been unable to reproduce. Only time will tell, maybe science will catch up and end the controversy.

In the meantime, I plan on trying the triple quench only after I have a repeatable single quench process for 5150/52100. I will make up my own mind then. And that may never happen, I am having too much fun with hamons to stray away from shallow hardening steels.

For the record, we owe the man who writes those articles a debt. He was and is a pioneer in our craft and has freely shared his knowledge and advanced the art of knifemaking. That said, he is repeatedly pushing a controversial heat treatment regime as accepted practice in media where beginners pick up on it and apply it inappropriately. He could be more clear in the articles that his methods and results apply only to the steals he uses and should be attempted only after a standard heat treat has been mastered. This new maker confusion causes stress to other forum contributors who are constantly having to correct the missunderstandings of beginners when they turn to a forum for help.
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Well said, BFrancios. I agree with almost everything you said;). I advise that any new makers take the time to learn about and understand the basic principles of metallurgy and material science. That will filter out most of the misinformation and wizardry.

Willie71 said:
I just tried a 52100 blade HT last week. I did a triple normalization without quenches, 1600, 1450, 1200 then 1475 for 10 min, quenched in Maxim DT48, 400f temper. The tip didn't harden, and could be bent over with my thumb. I was more worried about overheating rather than underheating the tip, and the color going into quench was uniform. Redid the 1475 for 10 min, into the Maxim again, made sure it was at room temp, then stuck it in the freezer overnight. Tip is now hard. I "think" I didn't quench long enough the first time, and the heat retained in the blade left the tip soft, and going into temper without fully reaching full hardening, added to the problem. At that point the tempering colors were all over the map. With the freezer cycle between the quench and temper, the temper colors were quite uniform. What do the more knowledgeable people think happened?
Click to expand...
Willie... what is your heat source. The fact that you said you were worried about overheating the tip, leads me to believe your were using a forge or dare I say it... a torch. Another statement you made about tempering colours had me raising my brows as well. The oxides produced during tempering is a notoriously bad indicator of temperature. Mine come out with all sorts of funky patterns at times. What are you tempering in?


For the record, I do not quench on the first normalization cycle. Here is my standard formula for 52100

1650F, air cool to black
1500F, oil quench
1450F, oil quench
900F, air cool to 400F, water quench
900F, air cool to 400F, water quench(yes, again)
Grind, file, drill, etc...
1200F, air cool to 400F, water quench
Heat slowly to 1475F, hold for 15-20mins, oil quench
Temper at 400F for 2hrs, check hardness (bump up temp as needed and repeat last heat for desired hardness)

Final quench and tempering temperatures do change a bit, depending on the steel but this formula would work for just about any high carbon non-stainless steel. L6 and a few other steels need more TLC to make life easier.
 
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I am heat treating in a forge. I use a muffle pipe as needed. The tempering is in a digitally controlled toaster oven with temp testing with a pyrometer. It's within 2f of the settings.
 
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