Tempering Chart for Common Knife Steels?

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David Stifle

David Stifle

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I've looked in the stickies and online for a chart which would show temering heats for common knife steels. Found one on Admiral Steels Website, but I'm not sure it applies to knife useage. What would be good is a chart that lists temps per steel type and the resulting Rc. Does anyone know if such a chart exists and where it could be found? Might also be a good sticky.
 
I don't have a handy chart, but on my website, I have a page with collected data sheets for common steels here. Most are tool and stainless steels. I haven't located data sheets for some; I've tried to stick to solid sources (i.e. steel producers if possble). Under heat treating data, there is usually information about tempering ranges and resulting hardness. In many cases in complex alloys, final hardness is dependent on multiple factors.

--nathan
 
oic0 said:
Also this http://www.cashenblades.com/heattreatment.html
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Kevin's site assumes the reader know what the various temps are per steel to harden downward to get to the desired RC. I can make some very good guesses based on my experiences with certain steels, but ...

What brought about this post was Stacy posted that 400 degree temper on 5160 would result in an RC of 52/53. I thought 400 degrees on that steel would result in a higher RC, around 58/59 or so. I've also seen guys say they temper W2 at 350 degrees to get a 60 Rc, and I always thought that would be a snap temp. I admit this is a weak area for me, but well, say you raise your temp 25 degrees, how much difference does this make? Where does a guy go to get a definitive handle on tempering heats and resultant hardness?
 
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darrin sanders said:
Very good info. here. One thing to remember about tempering is that the figures on most charts come from steels that are at full hardness out of the quench. If your blade doesn't reach full as quenched hardness your HRC #'s will be lower than the #'s listed on the charts.
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Good info........ A steel designed for a "fast" quench will not test the same (let's assume a tempering temp of 425 degrees) if it is quenched in "Burnt Motor Oil" versus Parks 50.

Suggested tempering temperatures/time are a guide base on "FULL HARDNESS". I can blow compressed air on a piece of 1095 and it will be definitely harder than it was before I started, but if I temper it at maybe 425, I might get through two sticks of warm butter before it needs to be sharpened.

We have to get the most of the steel based on temperature, time at temperature, quench medium, cryo if applicable, and tempering temps (according to intended use).

Tempering temps are just a very small part of our journey. The whole plan has to come together in order to get anywhere close to what we are looking for.

Robert
 
Robert Dark said:
Good info........ A steel designed for a "fast" quench will not test the same (let's assume a tempering temp of 425 degrees) if it is quenched in "Burnt Motor Oil" versus Parks 50.

Suggested tempering temperatures/time are a guide base on "FULL HARDNESS". I can blow compressed air on a piece of 1095 and it will be definitely harder than it was before I started, but if I temper it at maybe 425, I might get through two sticks of warm butter before it needs to be sharpened.

We have to get the most of the steel based on temperature, time at temperature, quench medium, cryo if applicable, and tempering temps (according to intended use).

Tempering temps are just a very small part of our journey. The whole plan has to come together in order to get anywhere close to what we are looking for.

Robert
Click to expand...

Sigh. I understand what you are saying Robert. Yet, moving all the variables aside, it seems a chart listing steels, temps and resulting hardness would be a very basic resource. I can get an RC tester and figure most of this out myself, rather than depend on all the conflicting info I've seen, but for the life of me, I can't figure out why there is NO chart on the entire internet, that I can find anyway, that lists this very basic info.
 
I know what you mean David. You go to 10 different websites and get 10 different answers.

It would be so nice to be able to go to one place to find info based on steels and cross-section sizes most commonly used by knifemakers. Such a chart would need to be based on accepted "full-hardness" procedures for both hardening and tempering.

Alas, there are too many variables and ideas, both scientific and perceived, in order to be able to really nail it down. In addition, if an individual, or even a well respected company were to attempt to put together such a "chart", there would always be the naysayers.

I guess that we just have to do what we can through research and testing in order to get the most out of what we have to work with. This forum contains a wealth of information, but you and I both know that just because we read it on the internet, doesn't necessarily mean its the truth.

Sort of like those posted gas mileage stickers in new cars.......... "Your mileage may vary". :)

Robert
 
Well, in a way, your response makes me feel better. While I would prefer a guide, at least my methods, flexing, cutting, edge retention testing, are probably as good as any other out there. Thanks for your input, Robert. I guess Knifemaking is part art, part science.
 
It is not basic info. There are many factors that determine what your as-quenched hardness is.

The best thing you can do for yourself is heat treat a series of coupons in the steel of your choice and have them Rockwell tested at full-hard, 375F, 400F, 425F, etc. Do 4-5pcs at each tempering heat. Just make sure your part is done as accurately and consistently as you can.(heat, quench, temper, grind to c/u.) If you are eyeballing temps, the results will be all over the place, anyway.

I temper 5160 at 400F and get 57-58HRC
 
Okay, I get it ain't basic info. But I'm failing to understand all the thousands of posts, articles, etc., that do not hesitate citing the ole "heat your XYZ steel to 1500, 1575, etc., degrees and quench," yet are unable to equally cite tempering heats for the same/ or various steels. I get all the variables, I'm just trying to get my head around the whole thing.

Edited to add: I'm a guys who sees thing as right or wrong, yes or no, rarely "it depends" or "maybe," etc., so perhaps that's why I am having trouble seeing all the undefinables related to this issue. Intellectually, I understand each knife is ground diffently, each has a unique purpose, and so on. I need to accept that this is not a problem with just one answer.:)
 
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David Stifle said:
Okay, I get it ain't basic info. But I'm failing to understand all the thousands of posts, articles, etc., that do not hesitate citing the ole "heat your XYZ steel to 1500, 1575, etc., degrees and quench," yet are unable to equally cite tempering heats for the same/ or various steels.
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It is easy to SAY heat to 1475F, quench in warm oil and this is what you get.... but think of all the variables in that single statement?
1475F - by eye w/ magnet? by forge, kiln? salt pot? was there a soak?... etc
Warm oil - Water? Canola? P50? Temperature? Agitation? Volume? Spine first? Tip first? Interrupted?... etc
You could end up with just about any combination with any as-quenched hardness. Even if you narrow it down further, you have the pre-HT regime to calculate, let alone the "human" variable.
Was the blade forged?
Was it normalized, annealed, spheriodized?
How many thermal cycles?
What is the cross section?

The tempering start point is forever shifting until you become consistent. Even then, it is still personal to your particular equipment and method. You can get an idea of the kind of hardness to expect given a HT recipe but you'd be foolish to assume everything went down like it was supposed to.

David Stifle said:
Edited to add: I'm a guys who sees thing as right or wrong, yes or no, rarely "it depends" or "maybe," etc.
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You can't get right or wrong handed to you from someone else... you can only get inspiration, options and guidance... the right or wrong has to come from applying that info to the best of your ability and evaluating the results for yourself.

David Stifle said:
I need to accept that this is not a problem with just one answer.:)
Click to expand...
I think you just did, bro:thumbup:
 
David Stifle said:
I'm a guys who sees thing as right or wrong, yes or no, rarely "it depends" or "maybe," etc...
Click to expand...

Haha, then you would HATE me as an instructor. My students joke about how often I answer questions with, "it depends." And the reason is that most of the time it does. We could create a chart chalk full of information from various steel data sheets, and as you, I could see that being extremely handy. Maybe I'll spend some time on it. However, it would have to be understood that the chart contains IDEAL information, and changes to any number of factors can change your outcomes.

Maybe it will help to state it this way: if you have accurate temperature control (a properly calibrated digitally controlled oven) and follow the heat treating instructions as suggested, then you should get in the ball park of the desired hardness. But you'll never know for sure until you try it and test it. That's why it is important to make notes about all your variables each time you heat treat so that you can get repeatable, reliable results.

--nathan
 
Rick - You and I have had a version of this conversation before.

David - I understand perfectly well your frustration. I want the same thing.

I'm a retired chef. I spent a good portion of my career following one recipe or another to achieve a desired flavor/color/texture/temp/cost. It works well, that method... repeatable, and transferable.
When not following a specific recipe however, an experienced chef/cook will revert to the fundamentals. i.e.:

"How to roast the perfect chicken"

1- 3# chicken, dead, plucked, washed, beheaded, washed again, set to room temp..... (the steel - annealed, shaped, normalized)
3 Tbsp olive oil
1 Tbsp kosher salt
1 tbsp cracked black pepper (these last three items are hand-sanding and blade prep)

Set oven to 450F ...... (pre-soak the forge/oven)
Place dead, clean, seasoned bird, in the center of the oven..... (blade prepped and situated in the forge)
Roast for 15 minutes..... (heat blade)
Turn oven down to 375F and continue cooking for one hour or until thermometer reads 165F at center-thigh.... (soak blade for time)
Remove cooked, dead, clean, seasoned, bird from oven and let rest for 15 minutes...... (quench in xxx oil)
Carve and eat.......... (remove decarb and finish the blade).

There. That will give you a perfect dead, beheaded, cleaned, seasoned 3# roast chicken ........ EVERY TIME.
I started with a known product. I processed with tested methods under known conditions.
I should have a predictable end product..... right?

That's the fundamental way to roasting a chicken.
What is the fundamental way to heat treat xxx steel?

Where is that simple recipe for heat treating 5160(and all the others).... without the additional variables like "said bird being the Siberian free-range variety cooked with kimchi and oyster stuffing, in a mesquite wood fired cob oven atop Mt Everest".

-Peter
 
Yes, it was a long and winding road, but I got there. I let go of my frustration and have accepted the sad, but unavoidable fact that there are too many variables to develop a set standand. I posted thinking it would be a simple issue. As I began to see it wasn't, I thought, we can put a man on the moon, a rover on Mars, transplant hearts, livers, kidneys, and so on, and we can't develop a chart for tempering? It could be, fellas, a tempering chart might be more complicated than all those accomplishments. Thanks for pulling me along, guys.
 
Anybody can make a chart. That isn't the problem. I can make you a chart for 1084, 1095, 5160, etc... but it would be based on MY process.

Check this site out for some tool steel tempering...... shhhhhhhhh .... don't tell everybody. Ha!

Here is another "chart"...
temper_colors_hardness_Page_1.jpg


You can find charts easily enough.....

15N20
15N20-TC.gif


1080
1080+-TC.gif


5160
TemperingChart.jpg
 
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Rick Marchand said:
Anybody can make a chart. That isn't the problem. I can make you a chart for 1084, 1095, 5160, etc... but it would be based on MY process.
Click to expand...

That would be great! Lets make it a sticky!
Maybe other experience knifemakers who do their own heat treat can do as well?
 
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