H1 Steel - How it Works

[tonijedi]

A question to Larrin and others who may be more accustomed with hardness tests: is it easy to measure the hardness so close to the edge of a blade? If I recall correctly from my student days the surface to test had to be level (90° with the tester). Or maybe this was the case with the machine I used.

No it isn't easy. Sandvik cross-sectioned the blade to get a flat surface. And with very thin sections microhardness is necessary.

Thank you for the explanation.

[kodai78]

Thanks Larrin! I’m very curious to see if you or anyone else can better explain or possibly debunk serrated edge behavior with H1. Also will you be able to determine if the edge of an H1 blades hardness changes with “work”? Assuming that work is slicing or cutting with said edge.

[ZrowsN1s]

Interesting work Larrin. I'm curious to see what you find out about serrated edge retention and edge hardening.

Maybe Spyderco hammers those serrations in :D

[Larrin]

So, you are saying that Crucible(or Spyderco) misinformed the general public ? ....." It is reported that Crucible metallurgists measured H1 hardness and found it to be approximately 58 Rc at the spine and harder at the edge, approximately 65 Rc "

I don't remember saying or implying that.

[Doc Dan]

There are a lot of anecdotal reports that the serrated edge gets harder has it is sharpened over time. This is something that I doubt, quite frankly, or we would see it in the plain edge, as well. But, there must be something that explains the edge performance of the serrated over the plain edge, and even over other steels. I am mystified by what it could be. True, serrated edges always cut longer than non serrated edges, but it would seem to be more than that, maybe. Could the inherent toughness of H1 be a factor? Could one of the elements or a combination of elements tend to run to the edge as the blade is worked thinner?

[SpyderEdgeForever]

Larrin, thank you! A very informative, educational, and fascinating article. What really jumped out at me are two of my personally-favorite properties in blades: Toughness and Corrosion resistance.

Regarding the mysteries of H1, I have a question for you and Doc and anyone else: Do you think there could be some way, using advanced or near-future versions of scanning electron microscopes, to somehow test the properties of H1 and other nitrogen steel alloys in real-time, so as to uncover more about them or would that not yield much new information?

[elena86]

There are a lot of anecdotal reports that the serrated edge gets harder has it is sharpened over time. This is something that I doubt, quite frankly, or we would see it in the plain edge, as well. But, there must be something that explains the edge performance of the serrated over the plain edge, and even over other steels. I am mystified by what it could be. True, serrated edges always cut longer than non serrated edges, but it would seem to be more than that, maybe. Could the inherent toughness of H1 be a factor? Could one of the elements or a combination of elements tend to run to the edge as the blade is worked thinner?

It's all about the so called "work hardening" ... is it a myth or what ... and I am most interested in serrated H1 edge ?! I remember Sal saying that in their CATRA tests H1 in spyderedge outperformed other steels ....I had the same experience with my H1 spyderedges in real life so ....

[Larrin]

Larrin, thank you! A very informative, educational, and fascinating article. What really jumped out at me are two of my personally-favorite properties in blades: Toughness and Corrosion resistance.

Regarding the mysteries of H1, I have a question for you and Doc and anyone else: Do you think there could be some way, using advanced or near-future versions of scanning electron microscopes, to somehow test the properties of H1 and other nitrogen steel alloys in real-time, so as to uncover more about them or would that not yield much new information?

I’m not sure what you mean by real-time.

[SpyderEdgeForever]

Larrin, thank you! A very informative, educational, and fascinating article. What really jumped out at me are two of my personally-favorite properties in blades: Toughness and Corrosion resistance.

Regarding the mysteries of H1, I have a question for you and Doc and anyone else: Do you think there could be some way, using advanced or near-future versions of scanning electron microscopes, to somehow test the properties of H1 and other nitrogen steel alloys in real-time, so as to uncover more about them or would that not yield much new information?

I’m not sure what you mean by real-time.

This is what I picture: Some form of scanning electron microscope that would allow a metallurgist to perform various blade tests (cutting, bending for torsion and toughness, etc), while watching the effects of these forces, stresses, and strains, at the level of steel crystals, actively, while the blade is mobile and being used. Sortof like a "Go Pro Electron Microscope". That way you could watch active blade testing unfold as opposed to having to keep the blade immobile on a surface, and examine it that way. It seems to me that the hardware for this is still too bulky, is that correct?

[sal]

Obviously Sandvik and Crucible had different findings. We can't explain the Serrated performance. though we've certainly experienced it. Crucible said they did micro hardness testing. We'll send Larrin some pieces to play with., Maybe he can add some info? We've been heavily promoting the steel for many years now with excellent results from customers. 'Tis a puzzlement as to why it does what it does?

sal

[Doc Dan]

There has to be a logical explanation for the edge holding properties of the H1.

[Doc Dan]

An article about the highly corrosion resistant H1 steel. It's very different than most other knife steels for several reasons, including that the steel is not heat treated by the knife manufacturer. In fact, the steel isn't quenched and tempered like typical knife steel. Learn about how it works instead here: https://knifesteelnerds.com/2019/06/24/ ... -it-works/

I do not know a lot about steels, except I have had it explained it is a lot like baking a cake or something, adding the right ingredients in the right proportions at the right temperature and cooling. Now, I do know that when making some things and you roll out the dough, you can get more of some ingredients at the edges as you smooth out the dough. A sort of flow happens and can be done with other materials. Of course, I might be crazy, but is it possible, that in the rolling and thinning, something is occurring that is pushing something to the thinner edges that accounts for the edge retention? Perhaps the pushing/cutting of the serrations into the blade exposes this in a manner normal sharpening does not? I do not know, I am looking for a reason and understanding.

[standy99]

Obviously Sandvik and Crucible had different findings. We can't explain the Serrated performance. though we've certainly experienced it. Crucible said they did micro hardness testing. We'll send Larrin some pieces to play with., Maybe he can add some info? We've been heavily promoting the steel for many years now with excellent results from customers. 'Tis a puzzlement as to why it does what it does?

sal

Butcher by trade for over 20 years and fisherman for over 40 years in tropical Northern Australia

H1 is the steel of the gods in my book.

I have seen more rusted knives than most in years gone by and even nowadays (on other boats). Have not had a Salt or Pacific salt with a touch of rust in the 10+ years I have been using them.

15 years ago I would get a new knife every Christmas. Not anymore, it’s back to socks and undies....

Have put more fisherman on to Spyderco H1 than anything and they always talk about how the can’t even get them to rust. One mate that’s a fishing guide thanks me every time I see him every couple of months and shakes his head just thinking of how good they are.

[Larrin]

This is what I picture: Some form of scanning electron microscope that would allow a metallurgist to perform various blade tests (cutting, bending for torsion and toughness, etc), while watching the effects of these forces, stresses, and strains, at the level of steel crystals, actively, while the blade is mobile and being used. Sortof like a "Go Pro Electron Microscope". That way you could watch active blade testing unfold as opposed to having to keep the blade immobile on a surface, and examine it that way. It seems to me that the hardware for this is still too bulky, is that correct?

It's hard to image something on a micron scale while cutting with it. Moving objects are difficult to image.

[Larrin]

I do not know a lot about steels, except I have had it explained it is a lot like baking a cake or something, adding the right ingredients in the right proportions at the right temperature and cooling. Now, I do know that when making some things and you roll out the dough, you can get more of some ingredients at the edges as you smooth out the dough. A sort of flow happens and can be done with other materials. Of course, I might be crazy, but is it possible, that in the rolling and thinning, something is occurring that is pushing something to the thinner edges that accounts for the edge retention? Perhaps the pushing/cutting of the serrations into the blade exposes this in a manner normal sharpening does not? I do not know, I am looking for a reason and understanding.

That's not how grinding an edge works. Or even forging one, for that matter.

[Larrin]

There has to be a logical explanation for the edge holding properties of the H1.

The only serrated edge CATRA testing I have seen was for ATS-34, which barely dulled at all over the 200 cut test. I don't know how H1 is supposed to have improved on that. Will have to see the actual results as Sal has suggested. https://knifesteelnerds.com/2018/11/26/ ... etention2/

[Wartstein]

There has to be a logical explanation for the edge holding properties of the H1.

The only serrated edge CATRA testing I have seen was for ATS-34, which barely dulled at all over the 200 cut test. I don't know how H1 is supposed to have improved on that. Will have to see the actual results as Sal has suggested. https://knifesteelnerds.com/2018/11/26/ ... etention2/

Now the disussion progresses to a point I (total layman) have always wondered about:

SERRATED H1 obviously holds an edge very good and very much longer than PLAIN H1, but I can´t remember any final statement , if that´s (more) due to the H1 itself or just / more due to the SERRATIONS (and NOT so much the steel).

So, to put it differently, presumably MOST to almost any steel(s) hold an edge longer in an serrated edge, and maybe the increase of edge holding from plain to serrated is roughly in the same range percentagewise in any steel compared to H1??

The last article you linked (https://knifesteelnerds.com/2018/11/26/ ... etention2/) seems to support that, or at least that we don´t know exactly!

(For those who did not or don´t want to read the article, here is a short section of it:
"The serrations mean the edge wears much more slowly than plain edges; the CATRA test is often performed with 200 cuts rather than the standard 60 because the edge wear is so much slower. The initial cutting ability of a serrated edge is significantly lower than a plain edge but after a sufficient number of cuts the serrated edge keeps going while the plain edge has dulled.")

[Larrin]

I believe Sal said that H1 and LC200N had a 4x increase in edge retention with a serrated edge vs 2x with S30V. I don't know if that is due to H1 having good serrated edge retention or because it had poor plain edge retention.

[curlyhairedboy]

Thanks again for the analysis, Larrin. This was a deep dive into a steel with a lot of legends told about it.

Relative serrated performance vs the same steel in plain edge seems to be the default comparison, but it might be very interesting to compare CATRA results with serrated H1 against serrated LC200n.

[Wartstein]

I believe Sal said that H1 and LC200N had a 4x increase in edge retention with a serrated edge vs 2x with S30V. I don't know if that is due to H1 having good serrated edge retention or because it had poor plain edge retention.

If true (and I don´t doubt Sal), that finally and actually IS an answer to what I was wondering about in my previous post: The "magical" increase in H1s edge retention from plain to serrated is in fact not that "magical" and not really/only due to the H1 (alone), but also true for other steels, and true to the same amount for for example LC200N... And in fact the edge holding of serrated LC200N must be better than of serrated H1 then (given that plain LC200N has better edge retention than plain H1, and both get 4 times "better" when serrated...)