Ankerson
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Ranking of Steels in Categories based on Edge Retention cutting 5/8" rope
- Thread starter Ankerson
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Hi Jim,Not sure on the hardness testing yet...
I will still test the 52100 Mule Team.
Regarding the CTS 204p test you did, could you hazzard a guess on the hardness? I have had a hard time finding anything published on how hard Spyderco ran than steel. Seems like maybe a point or so harder than the M390.
Thanks...
Ankerson
Knife and Computer Geek
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I don't know really...
I emailed Spyderco about it and the response from their CS was
"I’m sorry for the delay but I do not have access to the Rockwell standards for the steel and we do not publically post them. Once you receive your knife back if you feel it’s not holding a proper edge you are welcome to send it in for evaluation. Below are the directions you’ll need if you decide to send it in."
I think Sal has mentioned it though.
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Sal Glesser has, as you remembered, addressed it several times, but it may have been at Spyderco Forums rather than here. His response, basically, as I remember it, was that posting simple HRC levels is only part of the picture, and they feel that posting HRC numbers can be confusing or misleading. You can agree or disagree with that, but it's coming from someone who's got a lot of credibility, integrity and experience in this industry.
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Not trying to take anything away from Jim's hard work here, but this is one heck of a real world test. 
I note he even shaves his arm afterwards.
http://youtu.be/3ntmZKvsvVA
I think I'm really glad I bought one.
I note he even shaves his arm afterwards.
http://youtu.be/3ntmZKvsvVA
I think I'm really glad I bought one.
Sal is right to some extents and wrong to Others, IMHO.
Lets make an example with Elmax stainless steel using BU Datasheet.
My Elmax Mule has been tested to be at 58.5HRC.
This means:
1)That no deep-cryo has been done because Elmax easily trespass 60HRC with it with any HT combination. This also means that approximately 4% of retained Austenite will be there (bad).
2)Either 1050°C/150°C or 1100°C/200° have been used. Maybe 1080°C/>150°C<200°C. As a guess I'm prone to favour 1050/150 as being used as raising austenitizing temps can raise grain growth as well, if quenching is NOT done with proper overpressure or oil. Oil not used in batch production, so...
We have a 1050/150 HT, no cryo, 4% retained austenite and to complete the picture some of the Cr carbides will be the weaker M23C6 ones (that at 1050°C will remain undissolved), instead of the harder M7C3 ones.
The less than ideal HT finds a proof in Ankerson's own result at page 1 of this thread.
Edit:
Also such an HT would bring about a relatively poor stain resistance level, as there will be less Cr in solid solution than if Austenitized at i.e. 1080 or 1100.
So HRC value it is NOT completely indicative but, knowing the steel by means of detailed Datasheets, knowing that mass produced blades will not be oil quenched and will be vacuum heat treated, knowing phase diagrams and finally knowing HRC value, can tell us pretty much.
As a matter of facts per Ankerson's results Elmax Mule, with same HRC value of mine, belongs to Gr5.
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Sal has in the past commented directly on what the HRC on a given steel is. It is absolutely a valid data point to have combined with other info for interested parties.
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I cannot agree more.
The HRC gives a starting point with which to base your needs for selecting your next knife. Do you need a blade that holds it's edge longer, or an easier to sharpen blade?
Today's average high end blade buyer is becoming more educated about steels and tempering.
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He has responded in some specific cases, but this post from Spyderco forums from 2013 explains Spyderco's general position:
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I can understand why. If you look at tempering graphs, lets say M390, one can easily reach HRC60. But was it HRC60 aimed for maximum corrosion resistance or maximum wear resistance. Most here would want wear resistance, but general public seem to prefer "stainless". Then there is the issue as mentioned about why not this or that.......
Too much emphasis is put on HRC values rather than looking at the broader picture IMO.
Guys,
If someone is not interested in what the target or actual HRC is, fine, however, most knowledgeable folks are. Do you buy a vehicle and not check the MPG reported or rated horsepower etc?? We could go on and on. Would you be interested in or buy S110V run at a HRC of say 58? Would you be disappointed and or pissed to find out later that is what it came out at? Again, HRC outcomes are absolutely valid to know, along with other data, for those of us not buying gas station knives or late night stuff sold by hucksters. And I suspect as times go on we will see this info provided more and more by reputable makers, the changes driven by market forces.
Best
If someone is not interested in what the target or actual HRC is, fine, however, most knowledgeable folks are. Do you buy a vehicle and not check the MPG reported or rated horsepower etc?? We could go on and on. Would you be interested in or buy S110V run at a HRC of say 58? Would you be disappointed and or pissed to find out later that is what it came out at? Again, HRC outcomes are absolutely valid to know, along with other data, for those of us not buying gas station knives or late night stuff sold by hucksters. And I suspect as times go on we will see this info provided more and more by reputable makers, the changes driven by market forces.
Best
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I can understand why. If you look at tempering graphs, lets say M390, one can easily reach HRC60. But was it HRC60 aimed for maximum corrosion resistance or maximum wear resistance. Most here would want wear resistance, but general public seem to prefer "stainless". Then there is the issue as mentioned about why not this or that.......
Too much emphasis is put on HRC values rather than looking at the broader picture IMO.
Marthinius, nice to see you here again
As I explained to you before, with the help of phase diagrams, the best corrosion resistance in M390 (and the majority of SS) is scored by austenitizing at the max allowed temp and tempering in the low temp range. For M390 it is 1180°C/150°C. Even without deep-cryo and by vacuum hardening (N2 5bar) you'll land in the 61 realm, which is where M390 begins to deliver massive wear resistance. Add deep-cryo and you'll get 63HRC....
60HRC for M390 are just too less than recommended.
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Marthinius, nice to see you here again
As I explained to you before, with the help of phase diagrams, the best corrosion resistance in M390 (and the majority of SS) is scored by austenitizing at the max allowed temp and tempering in the low temp range. For M390 it is 1180°C/150°C. Even without deep-cryo and by vacuum hardening (N2 5bar) you'll land in the 61 realm, which is where M390 begins to deliver massive wear resistance. Add deep-cryo and you'll get 63HRC....
60HRC for M390 are just too less than recommended.
Even at HRC of 62, if the maker is tempering for maximum corrosion resistance it would be wrong to assume the same wear resistance as if it was tempered for maximum wear resistance at HRC of 62. Two different approaches to yield different results for different application depending on what the maker wants to incorporate for his design.
If you have the phase diagrams for M390 please forward it to me. It would be a nice to have as I have not heard back from Bohler yet with regards to CCT diagrams for M390.
Step by step.
Mass produced blades are vacuum HTd, Bohler says that max corrosion resistance (vacuum) is gained at 1180/150 and max wear resistance at 1180/500 (secondary hardening with a slight loss of stain resistance).
First question: are there two tempering temps where we get the same 61HRC value as 1150/150 vacum (or 62 and above with deep-cryo)?
Probably yes. But there will be no noticeable difference in wear resistance. Such a wear resistance difference at same 61 or 62HRC, at same austenitizing temp but with different tempering temps would be present and significant ONLY if using 500° tempering, which is secondary hardening.
Neels Roos and Elliot Williamson will confirm it to you.
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Question for someone in the know ................
When production blades are heat treated , there done a bunch at a time ........ will they not all come out the same or ?????
Will there be a difference in rockwell numbers in the same batch ???
Iam thinkin there will be a difference and not all come out the same because of doing them in large numbers .................?
When production blades are heat treated , there done a bunch at a time ........ will they not all come out the same or ?????
Will there be a difference in rockwell numbers in the same batch ???
Iam thinkin there will be a difference and not all come out the same because of doing them in large numbers .................?
There will be differences. Depending on a number of factors.
But top HT facilities will minimize them.
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Brick by brick.
Where did you get that tempering information? From discussing with Bohler SA and many knife makers they go by the recommended information:
BOHLER M390 MICROCLEAN
2100⁰F, 20-30 minute soak, Deep Freeze, 2 tempers at 390-480⁰F, 60-62 HRC
http://www.bucorp.com/files/KNIFEHEATTREATSUM2.pdf
Or:
With oil quench and subzero treatment they use the following tempering graph:
http://www.bohler-edelstahl.com/files/M390DE.pdf
Tempering for maximum corrosion resistance is between 200 - 300 C and Maximum wear resistance with secondary hardening is 520 C from the data sources I have spoken to.
I did look at your provided link and saw it is page 13 of ?. The rest of the document would be nice to read and educate oneself.
Exactly. That is my point. If a maker feels that his M390 in the specific design should have maximum wear resistance, temper at the 520 C region for secondary hardening. If he wants maximum corrosion resistance temper at the 200-300C region. Both can yield an HRC of +- 62 but with different characteristics from the same steel.
I know Neels quite well and his stance on M390.