New Discoveries found in 8Cr13MoV testing

[Mat_ski]

This is really awesome. I work with metallurgists (infrastructure and construction industry) and shared some articles from Dr Larrin website with them and they found it fascinating.

[Wandering_About]

So, how would the edge angle affect the results? Say, 30º inclusive vs 20º inclusive? What was the angle of the edge being tested and how thin behind the edge was the blade?

If you're asking about Larrin's CATRA testing, there's a section in this article describing their test blade design and it does have a brief discussion about the effect of edge angle. Scroll to "Knife Design and Sharpening" section: https://knifesteelnerds.com/2020/05/01/ ... fe-steels/

[Larrin]

Hey Shawn, Larrin,

I'd like to personally thank you for sharing this information on our forum. It is much appreciated. I'm sure our visitors also appreciate being able to come here and get this stuff.

sal

Thanks Sal!

[chronovore]

Always felt Spyderco's 8Cr13MoV was a tad bit underrated.

I don't feel like my opinions have changed about 8Cr13MoV. It grinds easy but it doesn't apex as well as other steels.

I did feel the testing put other steels in a better light rather than elevating 8Cr13MoV.

14C28N looks even better now.

Good points. It's been a while since I watched the video but it's important to remember that testing conditions don't necessarily mirror real-world production knives or how we use them. From what I recall, lots of 8Cr13Mov in production knives lives in the 55-58 HRC range with plenty on the softer side.

Spyderco's 8Cr13Mov is among the best I've ever used. (Coincidentally, the best came from Petrified Fish, which also delivers one of the best heat treatments on Chinese D2 in a budget knife.) Of course, the best 8Cr13Mov is still 8Cr13Mov. I'll always prefer 14C28N, which is strictly better as an all-rounder. While less tough, 9Cr18Mov is capable of much better edge retention, is widely available with a good heat treatment, and is much more stainless. The number of better alternatives at competitive prices overall has been increasing.

Another excellent point that I feel Outpost76 made a few years back is that "sharpness" is a spectrum. The problem he noted with 8Cr13Mov is that while it is easy to get very sharp, that very sharp fine edge rapidly degenerates into a ho-hum working edge. So while the total edge life is similar in Larrin's ratings, 14C28N always seems to provide a better quality edge for longer over the course of that lifespan versus 8Cr13Mov.

[JD Spydo]

Yes please to BBB HT protocols optimizing Sandvik steels for Spyderco.

Two blades I have used over the years that had Sandvik Blade Steel were both nice to use and both sharpened nicely too. Not sure how they would stack up in comparison to "8Cr13MoV". But the Swedes have been secretly known to make good steel for as long as I can remember.

There most definitely is a market for lower priced blade steels because most average knife users have no idea which steel they are using anyway. As far as comparing "8Cr14MoV" to VG-10??? I'll take Spyderco's VG-10 any day of the week. I still like VG-10 for hard use blades.

[Bolster]

...I still like VG-10 for hard use blades.

Why so? Asking because I associate hard use with toughness; tough VG-10 ain't.

[Matus]

wrong thread, sorry

[chronovore]

...I still like VG-10 for hard use blades.

Why so? Asking because I associate hard use with toughness; tough VG-10 ain't.

"Hard use" can mean different things. Toughness certainly comes to mind but higher edge retention might be part of the equation too. Of course, having both would be ideal.

While 8Cr13Mov is significantly tougher than VG-10, I wouldn't say VG-10 is hurting for toughness. For instance, VG-10 is a little tougher than N690, 154CM, BD1N, M390, or S90V. According to Larrin, it's on par with S30V or Elmax. Of course, none of those are going to compete with MagnaCut, 14C28N, Nitro-V, or some or the carbon steels like K390 or CruWear.

[Traditional.Sharpening]

This information is quite thought provoking and really shows another previously hidden variable to be accounted for ...

Exactly. These types of insights are only obtainable by careful testing and measurement, not from so-called "real world" impressions, opinions, accepted narratives, conventional wisdom, and anecdotes. Since the beginning of science, detractors have been throwing mud at laboratory experiments as "unrealistic." Yet without lab-based research, where extraneous variables can be held constant, controls established for valid comparisons, and results carefully observed, we'd still be living in a nonscientific world akin to the European medieval ages or earlier, where nearly all knowledge was "real world" and almost none of it was laboratory.

What's been discovered appears to be a mediating variable (banding) that moderates the effect of CATRA score to the point that it's actually opposite of expectations under certain conditions. Well done. Somebody should be getting a PhD awarded on research such as this.

There is nothing wrong with careful measurement and testing can present meaningful data. The problem comes when a model is developed and accepted in mass regardless of the fact that no attempt is made to actually ascertain whether or not the model actually models... real world use.

To my knowlege, this has never been done with CATRA despite wide acceptance on an almost comical level to such a degree that the term 'edge retention' is viewed by most people as a level easily defined by a steels CATRA test score. It isn't remotely true in the slightest of course because edges degrade and fail by means other than simple slow-wear.

The ironic thing is that steels which often score very low on a CATRA test are steels that I consider to be ideal when one considers the overall performance of a steel. I believe that steels with high wear resistance often have too many downsides to consider them to be an ideal steel in almost any application unless the user likes low sharpness and never sharpens.

[Bolster]

The ironic thing is that steels which often score very low on a CATRA test are steels that I consider to be ideal when one considers the overall performance of a steel.

It's not at all unusual in science, for a critic to say "you're measuring the wrong dependent variable." Sometimes the critics are wrong, sometimes they're correct. But it's incumbent on the critic to propose a new/different variable to measure as the outcome/effect/dependent variable. Since we can't use 'steels that TS considers to be ideal,' as that relies on a single observer, what objective and repeatable measurement, as an alternative to CATRA, do you propose?

[sal]

Hi Bolster,

Real World testing and forums as an alternate?

I'll never forget the prof's first statement in statistics; "You can prove anything, up to and including the Guillotine for dandruff control".

sal

[Bolster]

Hi Sal, good one; I'll trade you my stat prof's quote:

"It's possible to come to the wrong conclusions with statistics; it's even easier to come to the wrong conclusions without statistics."

Statistics aside, how do we measure 'real world testing' and forum opinions? I understand the desire for other dependent variables than CATRA. What measurements are objective and repeatable that could be used instead--and that aren't correlated highly with CATRA (that is, a different variable that measures a quality well, that CATRA does a poor job of measuring)?

[Steeltoez83]

I usually check Dr Larrins chart when I'm done performing all my cutting experiments on a steel and it's heat treat I'm only testing one sample usually, I'd prefer to average out 3 on the same model.

[sal]

"Back in the day" when the Eugene Knife show used to have a cutting competition, I had an opportunity to work with Ed Schempp on his Cutting Competition knife. Ed let me get a loupe on his edge before the contest, which he won, and again after the contest, which showed no difference.

His final cut was to go through 10, 1.0" free hanging ropes, with a single pass. This was after going through the sequence building up from one rope up to 10 ropes, adding one rope each time, and no sharpening between cuts. Quite a sight to watch.

Then he resharpened the knife and we ran it through our CATRA , where it tested poorly???? Since I was always an advocate for Real World Testing, this just reinforced my opinion that lab tests have their limits.

Even now, I use our K04SBL (serrated 6.5" Utility kitchen knife - blue handle) as a test bed in quite a few restaurants with their chief chefs. I get to check the knives every couple of months with magnification. I resharpen them when needed, and replace them when destroyed or stolen. Those using the knives always speak very highly of the knives in the commercial setting.

Just some thoughts to share.

sal

[Steeltoez83]

Thanks for sharing those stories Sal.

[Bolster]

Then he resharpened the knife and we ran it through our CATRA , where it tested poorly???? Since I was always an advocate for Real World Testing, this just reinforced my opinion that lab tests have their limits.

I dunno, Sal, to me it sounds like the free-hanging ropes test is, or could be, an alternate, repeatable, measurable test. And from your description, it sounds like it measured something important that CATRA didn't.

[Deadboxhero]

Convexity kills,

A lot of edges aren't at the angles people think they are yet this "hidden" edge geometry plays a HUGE role in the durability, cutting ability and cutting edge retention differences even more than steel in some cases.

This highlights the importance of testing with good control for variables.

"If you cannot measure it, you cannot improve it"
- Lord Kelvin

[Synov]

"Back in the day" when the Eugene Knife show used to have a cutting competition, I had an opportunity to work with Ed Schempp on his Cutting Competition knife. Ed let me get a loupe on his edge before the contest, which he won, and again after the contest, which showed no difference.

His final cut was to go through 10, 1.0" free hanging ropes, with a single pass. This was after going through the sequence building up from one rope up to 10 ropes, adding one rope each time, and no sharpening between cuts. Quite a sight to watch.

Then he resharpened the knife and we ran it through our CATRA , where it tested poorly???? Since I was always an advocate for Real World Testing, this just reinforced my opinion that lab tests have their limits.

This hardly surprises me. Cutting competitions are more about toughness+hardness than long term edge retention. That event only involved cutting 55 ropes. High edge retention steels go through hundreds of ropes before getting dull. For example, 4V is currently the steel of choice for at least two world champs. It's not exactly a high edge retention steel.