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Production Knife Companies That Have Performance Heat Treatments

Posted by jasonstone20 
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Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 02:05PM
I can't find the post or thread, but a few days ago I asked Cliff what steel he would want or suggest of an EDC blade. He mentioned that the blade should be at maximum hardness. This got me thinking, what production knife company runs their knives at maximum hardness, or near maximum hardness? The only production company I could think of that came close was Spyderco. From my small amount of samples used, their heat treatment seems to be closer to custom makers who heat treat for knife performance. Anyone have any other suggestions, or know who runs their blades at maximum hardness?

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 04:22PM
Quote
jasonstone20
I can't find the post or thread, but a few days ago I asked Cliff what steel he would want or suggest of an EDC blade. He mentioned that the blade should be at maximum hardness.

I don't think I would say that, as maximum hardness in a lot of cases would be the blade untempered. In general you would want a steel hardened so as to maximize its performance which is very specific to the type of work and the user. In general (very general) it is usually not a good choice to underharden blades to get higher toughness (than the recommended ranges) because you usually end up with a steel for a given toughness which is weaker/harder to grind than another steel.

To be specific, lets say you use AEB-L, and when you do a hardening similar to Roman Landes recommend you end up with 62/64 HRC. Now if at that hardness the steel doesn't have the toughness you require, and you decide to increase the toughness by :

-lower the austenization temperature
-not doing cryo
-increasing the tempering temperature

etc. .

It is likely that the blade you end up with which will be tougher, will be so because of things like :

-retained austenite
-larger carbide aggregates

which won't give you the performance you likely want. Instead you would be better off going with something like 12C27M which even when hardened with a similar manner as to AEB-L would produce a significantly softer and tougher blade (due to the %C which would be in the martensite). As an example, when Kershaw first used 13C26 (AEBL by a different name), it was hardened significantly under 60 HRC, high retained austenite, and the blade were just not very nice to work with. Edges were gummy, edge stability was poor, edge retention didn't impress anyone, etc. .
Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 04:53PM
Cliff,
What is the term for the highest hardness after being tempered? That is what I was referring to. I wish I could find the thread.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 04:58PM
I am not sure that is a term specifically. For some steels the maximum hardness after tempering you likely don't want. For example you don't want it in ATS-34 for example (or any similar stainless steel) because :

-you lose corrosion resistance, edge stability and toughness

and can end up with the same hardness and only light to moderate wear resistance gains.

For something like 1095 I would likely argue it should be hardened for maximum strength in a knife and if you didn't like the toughness in 66/68 HRC 1095, you are better off stepping the carbon % back (1084, 1070, 1050) etc.. Because at the same toughness, the lower carbon steel will be stronger and easier to grind.
Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 05:01PM
Found it.
Quote
Cliff Stamp
It has to be considered, this is a personal issue because it comes down to what you want. Here is what I want, if a knife is to be used for cutting mainly clean materials, no impacts :

-simple steel, hardened for maximum strength

For dirty materials, impacts :

-simple steel, ideally can be filed (< 60 HRC)
-hardened for maximum toughness (prevent chipping, gross fracture)

The reason is :

-sharpen very fast, high sharpness, minimal burr formation (that means it doesn't form)
-strongly resists damage (rolling or impact)
-abrades with simple abrasives (I have very fancy and expensive ones yes, including diamond and cbn, stones, sprays, papers, etc.)

This means :

-W1, O1, SB, AEB-L, M2, etc.

and then

-1084, L6, etc. .

My brother however hates sharpening, and he will use knives until they are extremely dull, like literally they are ripping material. He will favor something like D2 at maximum strength for a smaller knife, similar tastes on larger knives.

The main thing is you have to match the steel/hardening to your preferences.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 05:02PM
Quote
Cliff Stamp
it should be hardened for maximum strength

This is what I was looking for.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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cKc
Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 05:05PM
I'm not sure there is an exact term?

but I don't think you are always targeting the very hardest you can get after the quench. you are looking for the hardest you can get that provides the optimal grain structure. lowering hardness doesn't necessarily increase toughness for example.

i think each steel as designed, has a heat-treatment that is determined to be optimal or near optimal and at that point you have the best balance of hardness, toughness, wear that this particular steel composition can attain.

now if you take that steel one of the qualities is not good enough, then you don't "tweak" and adjust the properties to make 1 of them what you want at the sacrifice of the others.. you simply pick another steel that will get closer to where you want to be, which is why there are so many steels in existence.

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 05:12PM
cKc,
I was thinking of when someone would say, "AEB-L only gets to 62HRC (even though with certain HT you can get it to 64HRC) ". That type of hardness.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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cKc
Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 05:50PM
Quote
jasonstone20
cKc,
I was thinking of when someone would say, "AEB-L only gets to 62HRC (even though with certain HT you can get it to 64HRC) ". That type of hardness.

Well it is a tricky one. i mean. someone doing one knife, where the quenchant is literally 1 second movement from the kiln is going to get a higher potential hardness than a factory that has to move the mass a greater distance..

because of this issue, I started getting my heat-treater to use custom built plates of stainless that were over 1" thick, and all the blades were stacked about 4 high, and clamped between these massive plates, then then entire thing was heated and quenched as a single large block to keep better thermal mass.

that type of statement, is where every HT'er might say "my secret recipe can do better" etc. higher temp in over etc etc. but being able to reach it may not mean its good for the steel.


you are going for optimal hardness for the steel, other than saying optimal hardness. I'm not sure there is a term.

there is also the fact that cryo might be optional, or not, and might increase it 1-3 points.. so for one person saying reaches 62 could be correct for what he is doing where another 64 can be correct. is either wrong?

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
Re: Production Knife Companies That Have Performance Heat Treatments
June 15, 2020 07:17PM
Just as a point of clarification, HRC testers are not accurate to 0.1 HRC for a large number of reasons, and HT'ing specifications are not without error due to random variations in time and temperature. An oven isn't exactly 1850 F (or whatever), the knife doesn't instantly go from over to quenchant, the quenchant isn't uniform in temperature (especially when the knife hits it), and so on.

Thus even if you are doing a HT which would exactly get 64 HRC, you are likely to read +/- 2 HRC points for a number of reasons (usually biased towards lower because almost everything which is less than ideal in hardening makes the blade softer).