Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Larrin » Tue Dec 03, 2019 6:54 am

Cambertree wrote:
Tue Dec 03, 2019 6:05 am
That's an interesting point and well worth further discussion on the forum, I think. Especially as lower carbide steels will have greater edge stability at more acute angles - which in turn has a strong influence on edge retention.

It's probably veering a little off topic for this thread - sorry Larrin - but I'm reminded of this experiment by Cliff Stamp, where he tested how much more acute the microbevel angle of VG10 needed to be to match the edge retention of S30V on 1/2" manila hemp rope.

The answer was a mere 2 1/2 degrees. Yep, that's right - just by applying a slightly more acute microbevel angle, VG10 would match S30V. Then consider the ease of resharpening and relative toughness, too.

https://youtu.be/OSDFLgq4EDs

The implication is that sharpening a lower carbide volume steel to an even more acute angle may outstrip the edge retention of a higher carbide volume/more wear resistant steel, which requires a more obtuse edge angle to stay stable.

Don't get me wrong, I love that Spyderco provide these interesting high hardness, high carbide volume steels for us to play with, but there's certainly something to think about in Bornin1500 and Cliff's points.
Sure I've written about this frequently. Here is one article with some links back to others such as a whole article on edge stability: https://knifesteelnerds.com/2019/08/05/ ... -not-fail/
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Pelagic » Tue Dec 03, 2019 8:34 am

I can't take that chart to heart. Does anyone here really think s125v is going to consistently outcut Maxamet at 5 HRC points softer? It also has ZDP beating out s30v by a negligible margin while being 4 HRC points higher. Is 440C REALLY going to cut TWICE as much as 52100 while being a point softer?

Out of numerous cut tests I've seen online, I cannot recall any that reflect Maxamet only outcutting 440C 2—fold while being a whopping NINE HRC points higher. I know every test is has its flaws, but if this chart were accurate I would have at least seen one test that backs up some of these numbers. And to be fair, much of the data makes sense, but there are a few that seem quite far—fetched, imo.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby TomAiello » Tue Dec 03, 2019 9:07 am

I think a lot depends on actual real world use. Everyone does different things with their knives and a guy who is regularly cutting wallboard or roofing shingles is going to want a different edge angle, steel and HRC than a guy who is mostly cutting cardboard.

How many of us really cut old fashioned hemp rope, anyway?

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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Mm1313 » Tue Dec 03, 2019 9:55 am

Pelagic wrote:
Tue Dec 03, 2019 8:34 am
I can't take that chart to heart. Does anyone here really think s125v is going to consistently outcut Maxamet at 5 HRC points softer? It also has ZDP beating out s30v by a negligible margin while being 4 HRC points higher. Is 440C REALLY going to cut TWICE as much as 52100 while being a point softer?

Out of numerous cut tests I've seen online, I cannot recall any that reflect Maxamet only outcutting 440C 2—fold while being a whopping NINE HRC points higher. I know every test is has its flaws, but if this chart were accurate I would have at least seen one test that backs up some of these numbers. And to be fair, much of the data makes sense, but there are a few that seem quite far—fetched, imo.
I had the exact same thoughts reading this. Very informative but some things seems very farfetched and quite flawed. Particularly considering the edges & info that has been seen from the "professional" testers. I appreciate all the hard work to put together an article like this and had quite a good deal of quality info in it about the backstory.

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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Larrin » Tue Dec 03, 2019 10:54 am

Actually there is a very strong correlation between the results of rope cutting testers and the CATRA test. Perhaps your perception is different than their actual results. https://knifesteelnerds.com/2019/02/11/ ... rformance/
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Pelagic » Tue Dec 03, 2019 11:15 am

Larrin wrote:
Tue Dec 03, 2019 10:54 am
Actually there is a very strong correlation between the results of rope cutting testers and the CATRA test. Perhaps your perception is different than their actual results. https://knifesteelnerds.com/2019/02/11/ ... rformance/
Of course my perception is different than these results, that's exactly what I stated. I understand what you're saying, the immediate "actually you're wrong" stance may not be appropriate.

Image

I recommend everyone watch SuperSteelSteve's latest video on the consistency and reliability of CATRA testing. The comment in the screenshot is by someone who is far from ignorant on this subject. I'm not trying to be critical, but I do not see CATRA as the law of the land. But maybe all this info is a well orchestrated lie, or maybe I'm just missing something. This is just my belief and I realize anything is possible.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Larrin » Tue Dec 03, 2019 11:22 am

Those people were disappointed in the sharpening by the CATRA organization. They are apparently using that disappointment to discredit the tester itself. I don't know why they want to burn the whole thing down.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Larrin » Tue Dec 03, 2019 11:25 am

Pelagic wrote:
Tue Dec 03, 2019 11:15 am
Of course my perception is different than these results, that's exactly what I stated. I understand what you're saying, the immediate "actually you're wrong" stance may not be appropriate.
If you show me a test between 440C and Maxamet that shows a bigger difference we can discuss what might lead to that, but otherwise it's just an argument of perception.

Carbides have a much stronger effect on wear resistance than hardness. See this chart, for example:
Image
Edge retention testing is a wear test unless there is rolling or chipping from cutting hard materials or with very thin edges. In that case hardness would matter more than purely wear resistance.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Pelagic » Tue Dec 03, 2019 11:27 am

Larrin wrote:
Tue Dec 03, 2019 11:22 am
Those people were disappointed in the sharpening by the CATRA organization. They are apparently using that disappointment to discredit the tester itself. I don't know why they want to burn the whole thing down.
How do really know what info to trust?

Do you agree that some of the values in the chart seem off? 5 HRC points a HUGE difference for s125v beating out Maxamet, wouldn't you say?
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Larrin » Tue Dec 03, 2019 11:31 am

Pelagic wrote:
Tue Dec 03, 2019 11:27 am
How do really know what info to trust?
That's a bigger philosophical discussion. I've never used any data generated by the CATRA organization itself. Only a knife company who provided me their dataset and showed me their testing process using a tester made by CATRA many years ago. The edge retention tester should be evaluated on its own terms.
Do you agree that some of the values in the chart seem off? 5 HRC points a HUGE difference for s125v beating out Maxamet, wouldn't you say?
See my prior post about wear resistance vs hardness.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Pelagic » Tue Dec 03, 2019 11:34 am

Larrin wrote:
Tue Dec 03, 2019 11:31 am
Pelagic wrote:
Tue Dec 03, 2019 11:27 am
How do really know what info to trust?
That's a bigger philosophical discussion. I've never used any data generated by the CATRA organization itself. Only a knife company who provided me their dataset and showed me their testing process using a tester made by CATRA many years ago. The edge retention tester should be evaluated on its own terms.
Do you agree that some of the values in the chart seem off? 5 HRC points a HUGE difference for s125v beating out Maxamet, wouldn't you say?
See my prior post about wear resistance vs hardness.
What is the total carbide volume difference between Maxamet and s125v and how much vanadium carbide does s125v have over Maxamet?
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Deadboxhero » Tue Dec 03, 2019 12:05 pm

Pelagic wrote:
Tue Dec 03, 2019 11:27 am
Larrin wrote:
Tue Dec 03, 2019 11:22 am
Those people were disappointed in the sharpening by the CATRA organization. They are apparently using that disappointment to discredit the tester itself. I don't know why they want to burn the whole thing down.
How do really know what info to trust?

Do you agree that some of the values in the chart seem off? 5 HRC points a HUGE difference for s125v beating out Maxamet, wouldn't you say?
Might not be as far fetched as you think with controlled slice cut testing.

There aren't any knives in s125v for you to compare unfortunately. (Hey Sal :D)


S125v at 63rc cutting 3/4 Manila Rope vs Rex121 which has both more carbide volume, Vanadium carbide volume and hardness advantage.
Rex 121 obviously won but it's interesting to see that s125v at 63rc is no slouch.

I tried to point this out in the k390 test thread about hardness and carbide hardness and volume and why K390 at 63.5 can outcut Rex 45 at 67rc.

Image

S125v
Image


Rex 121
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Pelagic » Tue Dec 03, 2019 12:29 pm

K390 outcutting REX45 despite REX45 being a few points harder seems feasible given the carbide situation. But s125v beating Maxamet despite a 5 point difference is very surprising to me, since Maxamet has a very high carbide volume. It's interesting to see such varying opinions and test results concerning the importance of hardness. In this case, hardness almost seems pointless, and in other cases, it can seem extremely important. In this case, it also appears to be pointless to own any ZDP-189 (over s30v), as you lose toughness, strength, and loads if corrosion resistance to cut a minuscule amount longer. Interesting to say the least.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Larrin » Tue Dec 03, 2019 12:32 pm

Pelagic wrote:
Tue Dec 03, 2019 12:29 pm
K390 outcutting REX45 despite REX45 being a few points harder seems feasible given the carbide situation. But s125v beating Maxamet despite a 5 point difference is very surprising to me, since Maxamet has a very high carbide volume. It's interesting to see such varying opinions and test results concerning the importance of hardness. In this case, hardness almost seems pointless, and in other cases, it can seem extremely important. In this case, it also appears to be pointless to own any ZDP-189 (over s30v), as you lose toughness, strength, and loads if corrosion resistance to cut a minuscule amount longer. Interesting to say the least.
I think we can find much to agree on. I agree that test results are often surprising and different test types may reveal slightly (or greatly) different answers. We can learn by exploring why one is yielding a different result, and learning the mechanisms that control it. I don't think that hardness is unimportant, but how it all balances out between various carbide contents and hardness levels can be surprising.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Larrin » Tue Dec 03, 2019 12:39 pm

Pelagic wrote:
Tue Dec 03, 2019 11:34 am
What is the total carbide volume difference between Maxamet and s125v and how much vanadium carbide does s125v have over Maxamet?
Unfortunately the answer to that is not cleanly available. I have experimentally reported S125V carbide numbers from the S90V patent, but it was an earlier version of S125V that is somewhat different than the current one (Mo significantly lower, for example). Maxamet has no experimentally reported carbide volume numbers in terms of breakdown between M6C and MC, but I do have calculations from Thermo-Calc. But here is the comparison between those two:

S125V: 16% vanadium-enriched M7C3, 12.5% MC
Maxamet: 3.6% M6C, 13.2% MC

Using Thermo-Calc the current S125V is 12.6% vanadium-enriched M7C3 and 16.2% MC

It may be safe to assume that S125V has significantly more overall carbide than Maxamet, perhaps as much as 70% more.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Deadboxhero » Tue Dec 03, 2019 12:53 pm

Pelagic wrote:
Tue Dec 03, 2019 12:29 pm
K390 outcutting REX45 despite REX45 being a few points harder seems feasible given the carbide situation. But s125v beating Maxamet despite a 5 point difference is very surprising to me, since Maxamet has a very high carbide volume. It's interesting to see such varying opinions and test results concerning the importance of hardness. In this case, hardness almost seems pointless, and in other cases, it can seem extremely important. In this case, it also appears to be pointless to own any ZDP-189 (over s30v), as you lose toughness, strength, and loads if corrosion resistance to cut a minuscule amount longer. Interesting to say the least.
Well it's all very complex, one would have to be using, making and testing all these different steels with different HT and Geometry to truly grasp it and connect all the dots.

At the end of the day, controlled testing is not the same as what anecdotally people will experience or express with how they use and sharpen in the real world.
So testing may show one thing and users will see another.

Sal knows this very well, they have CATRA testing, hardness testers, and many other tools in the Spyder lab.

But he knows it's the people that decide, so rather than overwhelm folks with data that is only pertinent to the competition and hardcore geeks they privately R&D, test and QC and send it out to the world for the TRUE test.



Controlled testing should be used to see how the steels compare to each other away from other factors so we can understand how they stack to each other. There are so many variables and all the steels are pretty dang good so it's difficult to see in day to day use per say.


This next part is for new people.

Testing is not to be used as Gospel or that any given user will get exactly this many more cuts than another steel.
It's to sort through how things work by isolating factors so we can see independently in a sand box what we may want to acentuate or improve.


So in reality if someone feels that 1095 holds a longer edge for them, that's fine, but it's NOT the steel and other variables are at play.
Last edited by Deadboxhero on Tue Dec 03, 2019 12:55 pm, edited 2 times in total.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Pelagic » Tue Dec 03, 2019 12:54 pm

Larrin wrote:
Tue Dec 03, 2019 12:39 pm
Pelagic wrote:
Tue Dec 03, 2019 11:34 am
What is the total carbide volume difference between Maxamet and s125v and how much vanadium carbide does s125v have over Maxamet?
Unfortunately the answer to that is not cleanly available. I have experimentally reported S125V carbide numbers from the S90V patent, but it was an earlier version of S125V that is somewhat different than the current one (Mo significantly lower, for example). Maxamet has no experimentally reported carbide volume numbers in terms of breakdown between M6C and MC, but I do have calculations from Thermo-Calc. But here is the comparison between those two:

S125V: 16% vanadium-enriched M7C3, 12.5% MC
Maxamet: 3.6% M6C, 13.2% MC

Using Thermo-Calc the current S125V is 12.6% vanadium-enriched M7C3 and 16.2% MC

It may be safe to assume that S125V has significantly more overall carbide than Maxamet, perhaps as much as 70% more.
Wow, I had no idea. That is impressive.
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Larrin » Tue Dec 03, 2019 12:56 pm

Pelagic wrote:
Tue Dec 03, 2019 12:54 pm
Wow, I had no idea. That is impressive.
Or worrisome if you're trying to balance wear resistance and toughness, having all that carbide. :)
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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby sal » Tue Dec 03, 2019 1:10 pm

As Shawn stated, it takes, in my opinion, more than one test to find truth, if that's possible? We've done many tests on steels with our CATRA. Still we find questions.

We've changed the thickness and shape of our test mules and we're in the process of retesting everything to verify previous rests.

That's why we really like to get feedback from folks out there actually using the steels. We're really fussy on Heat Treat so we prefer to use our own pieces.

sal

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Re: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Postby Sumdumguy » Tue Dec 03, 2019 1:25 pm

sal wrote:
Tue Dec 03, 2019 1:10 pm
As Shawn stated, it takes, in my opinion, more than one test to find truth, if that's possible? We've done many tests on steels with our CATRA. Still we find questions.

We've changed the thickness and shape of our test mules and we're in the process of retesting everything to verify previous rests.

That's why we really like to get feedback from folks out there actually using the steels. We're really fussy on Heat Treat so we prefer to use our own pieces.

sal
Well, I'm having a blast helping with the testing! LC200N has been a fantastic performer and is incredibly tough!
I used to compare it to VG-10, but I don't feel the same anymore. After countless hours of side by side usage, LC200N has shown a marked improvement in edge retention(fine and working), sharpening response, corrosion resistance and toughness.

There's usually a tradeoff when it comes to these steel's attributes, but I have yet to find one with LC200N. Truly remarkable!

Now, if I could figure out how to get paid for this! :P


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