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by Larrin
Wed Dec 11, 2019 9:28 am
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

Thank you for the wealth of data and charts Larrin. I'm a huge fan of the unbiased data and have been following your blog for a few weeks by now. Perhaps the biggest point of confusion most people have is with respect to error propagation. Most people see data points and assume they're absolute val...
by Larrin
Wed Dec 11, 2019 8:27 am
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

JuPaul wrote:
Wed Dec 11, 2019 8:22 am
So...kind of an off-topic (and maybe dumb-a**) question, but why are Rockwell hardness units sometimes abbreviated as "Rc" and sometimes as "HRC"? Are both correct? Any difference?
HRC is probably more correct. I use them both.
by Larrin
Wed Dec 11, 2019 7:36 am
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

Do you honestly believe no one looks at them? I did look at the chart, but upon closer inspection it was clear that it indicates 1095 is considerably tougher. There are a lot of data points in a very small space. Throughout all my posts I stated that there was something I'm not understanding. I fou...
by Larrin
Wed Dec 11, 2019 6:39 am
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

I clearly wrote that they are in "the same range." I don't know why I post charts if no one looks at them.
by Larrin
Mon Dec 09, 2019 4:59 pm
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

Larrin, Don't some blade smiths still make the tangs softer than the blade when they are forging to give them extra strength, toughness would be the better term I think? I know some used to, not sure if they still do or not. Something I was thinking about the other day, figured I would ask. Jim I d...
by Larrin
Mon Dec 09, 2019 4:15 pm
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

A knife edge rolling does not necessarily mean the steel has high toughness. It means the steel is too soft for the applied stress.
by Larrin
Mon Dec 09, 2019 6:33 am
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

How am I begging that question? "tough enough for a knife" is not what the OP asked. I am talking about impact toughness only, between 1-2 steels, in regard to resistance to fracture, because this is what the OP asked about. There are many other people bringing up irrelevant points but despite poss...
by Larrin
Mon Dec 09, 2019 6:32 am
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

It has been known by metallurgists for several decades that 1095 and O1 have average-at-best toughness. It is not due to carbides but rather poor "matrix toughness," presumably due to high carbon in solution and plate martensite. I haven't seen much explanation on that one, probably not considered i...
by Larrin
Sun Dec 08, 2019 6:37 pm
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

I think the edge geometry is much more important than heat treatment if we are comparing S30V/1095 knives for chopping or prying tasks. If it’s 15 dps both 1095 and S30V would fail. 1095 can get some more toughness it’s taken down to lower hardness. But using a lower carbon steel would increase the ...
by Larrin
Sun Dec 08, 2019 2:55 pm
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

Funny, every 1095 knife over ever owned has more resistance to fracture than every s30v I've ever owned by a significant margin. I use my old hickory butcher's knife as a machete on hardwood. I chop trees down hitting the trunk as hard as I can. Keep in mind, this is a butcher's knife, with geometr...
by Larrin
Sun Dec 08, 2019 2:17 pm
Forum: Spyderco General Discussion
Topic: Newbie steel question.
Replies: 75
Views: 3253

Re: Newbie steel question.

1095 and O1 do not have particularly high toughness. In the same range as S30V. https://i0.wp.com/knifesteelnerds.com/wp-content/uploads/2019/12/Low-alloy-steel-toughness-12-5-2019.jpg https://i2.wp.com/knifesteelnerds.com/wp-content/uploads/2019/12/Stainless-steel-toughness-12-5-2019.jpg https://i1...
by Larrin
Fri Dec 06, 2019 6:36 am
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

Is there a theoretical upper limit to steel hardness? Not really. The highest I have seen is in the 72-73 Rc range. Though the Rockwell C scale is not particularly good for high hardness measurements, as the standards only go up to 65 or 70 Rc, and it becomes quite nonlinear above 70 Rc. There are ...
by Larrin
Tue Dec 03, 2019 12:56 pm
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

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. :)
by Larrin
Tue Dec 03, 2019 12:39 pm
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

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 S1...
by Larrin
Tue Dec 03, 2019 12:32 pm
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

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 con...
by Larrin
Tue Dec 03, 2019 11:31 am
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

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 retentio...
by Larrin
Tue Dec 03, 2019 11:25 am
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

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 t...
by Larrin
Tue Dec 03, 2019 11:22 am
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

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.
by Larrin
Tue Dec 03, 2019 10:54 am
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

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/
by Larrin
Tue Dec 03, 2019 6:54 am
Forum: Spyderco General Discussion
Topic: Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
Replies: 47
Views: 1751

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

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 La...

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