s30v

[Cliff Stamp]

Here is an english reference to start reading on Landes :

http://www.bladeforums.com/forums/showthread.php?t=344902

-Cliff

 

[Hang_them_later]

Here is an english reference to start reading on Landes :

http://www.bladeforums.com/forums/showthread.php?t=344902

-Cliff

All I get is links about Tea and Coffee:


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etc
etc

 

[db]

I don’t understand. This thread is about larger knives and Cliff is argueing about edge stability of very thin polished edges. Effects are at the thickness of under a micron? I’m not going to pretend to know how most people maintain and refine edges for large knives. But, how is this related?

You can get there with fairly high carbide steels, in general as long as the abrasive is hard/sharp enough. There is some difference, but is is REALLY small.
I have run trials on sharpness testing on chisels for Beach and there are differences in steels but I can just barely say they are significant (0.05 p-value).
..
one is going to hold a very thin and polished edge better.
-Cliff

The edge thickness would not matter as much as the edge angle itself as the carbides are in the micron level so the edge stabilizes very quickly. Long before
it is worn back to the primary.

-Cliff

 

[Jerry Hossom]

Yeah, I get the same link as Hang does.

5% chromium makes the steel air hardening and that's one reason you see a number of steels made with that level of chromium. A2 for example. The alloying also makes the steel stronger. The way to reduce the chromium carbides is reduce the carbon, which of course also reduces things like wear resistance and strength.

You make an excellent point db.

 

[hardheart]

post 17 in that thread

maybe a mistaken assumption on my part, but I thought finer steels would be better because cracks would not spread as readily. They seem to roll instead, even around 60Rc, which I always personally preferred to chipping for hard use knives. I damage big knives a lot more than folders, so easier sharpening is a plus.

 

[Silverdagger]

It seems as if this thread gives credence to the old "Buy a Buck Knife and Forget about it".

The 420 HC is about as good as S30V in many ways.

 

[Jason B.]

what do you mean 420 performs noting like my S30V knives

 

[TinyDee]

420 is trash

 

[Torm]

what do you mean 420 performs noting like my S30V knives

Likewise. I've been really impressed with my S30V blade's edge retention. Maybe I misunderstoof Cliff's point but it seems like the Lande's test is using an extremely fine edge and not a more common utility edge profile.

 

[Cliff Stamp]

... it seems like the Lande's test is using an extremely fine edge and not a more common utility edge profile.

As the edge angle thickens then the edges will become inherently stable by geometry and there is thus no advantage to having the steel itself have a high edge stability. Of course the higher the edge angle the lower the cutting ability.

-Cliff

 

[Jason B.]

i put a very fine edge on my S30V and it holds up for a long time

 

[Jerry Hossom]

And here I was beginning to think it was just me...

 

[knarfeng]

Likewise. I've been really impressed with my S30V blade's edge retention. Maybe I misunderstoof Cliff's point but it seems like the Lande's test is using an extremely fine edge and not a more common utility edge profile.

As the edge angle thickens then the edges will become inherently stable by geometry and there is thus no advantage to having the steel itself have a high edge stability. Of course the higher the edge angle the lower the cutting ability.
-Cliff

At what angle would you expect an S30V edge to become stablilized by geometric factors?

 

[Cliff Stamp]

There are a number of factors to consider there such as the heat treatment which will effect the carbide volume and hardness and of course the user tolerances. What do you consider sharp? There are guys here who will sharpen knives when they stop push cutting newsprint then there are guys who will only sharpen thier knives when they can not cut their skin under high pressure. But as a general rule, subject to variances from the above, I would say around 20 degrees or so. Read the above link from Landes for a much greater detailed responce to this including his PDF file on the model of the edge which deals with this exact issue.

-Cliff

 

[enderwiggin]

So if I'm reading this right, "440 Series Stainless" is fine for large, chopping knives where edge 'sharpness' is is at a minimum, but 420 is still cheap, fast-wearing steel used because it's inexpensive and/or "easy to sharpen."

Thankfully no one is claiming S30v is 'inferior' to 420 as an edge-holder on a sharp knife, I read Cliff's post a few pages back and my head just about exploded.

 

[Cliff Stamp]

Thankfully no one is claiming S30v is 'inferior' to 420 as an edge-holder on a sharp knife...

Correct, no one is claiming it, several people have MEASURED it and material science supports it. Buck even has CATRA data which shows for example 420HC easily outcutting BG-42 when the 420HC blade has a more optimal profile. Since the finer grained steels are more stable at lower edge angles this should lead to an obvious conclusion in regards to wanting high cutting ability in knives and the ability to retain very sharp edges.

-Cliff

 

[Jerry Hossom]

So 440A would have superior edge holding to 440C, right?

Has Buck actually published these data?

 

[db]

As the edge angle thickens then the edges will become inherently stable by geometry and there is thus no advantage to having
the steel itself have a high edge stability. Of course the higher the edge angle the lower the cutting ability.

At what angle would you expect an S30V edge to become stablilized by geometric factors?

There are a number of factors to consider there such as the heat treatment which will effect the carbide volume and hardness
and of course the user tolerances. What do you consider sharp?
.. .
as a general rule, subject to variances from the
above, I would say around 20 degrees or so.

-Cliff

There are very few people who are sharpening their large knives at 20 degrees, 10 per side, or under on large knives. Heck there are darn few that sharpen that low on their small knives or even on kitchen knives. However, if you are you can use a micro bevel witch even Cliff himself commonly posts will not significantly effect the cutting ability even with a micro bevel of 10, 15, or even 20 degrees per side. You can even use a shallow convex edge bevel witch does the same thing as the micro bevel only better in my opinion, to get a highly stable edge with a high level of cutting ability. Thus you get the benefits of both a stable edge with high wear resistance, and even corrosion resistant.

 

[Cliff Stamp]

So 440A would have superior edge holding to 440C, right?

It has greater edge stability yes. Edge holding without any qualifiers is meaningless as it isn't undefined. Edge stability is a material property. Edge holding is dependent on a number of properties, including edge stability. The exact property matrix is dependent on the type of cutting. S90V for example has a very low edge stability and thus the edge holding will be FAR inferior to 420HC in a number of applications.

Has Buck actually published these data?

Yes. I cited it several times in various articles. It is in the Buck knives forum. The curves follow the exact same pattern that Landes notes in his book. THis is not surprising since they (Germans) have been doing that since the 1920's. They left it behind shortly after as they found it was not well correlated to use by people, not surprising as it was done by machines. They used other techniques and found much greater differences for the fine grained and low carbide steels and worked significantly on edge stability, i.e., micro-fracture.

-Cliff

 

[Jerry Hossom]

S90V for example has a very low edge stability and thus the edge holding will be FAR inferior to 420HC in a number of applications.

"Edge holding" is I guess meaningless only when I use it. When you use it in the same paragraph it's ok?

Let's try another word. You're saying that 440A has better edge retention than 440C, right?

Do you have a link to exactly where Buck has published the 420hc vs BG42 data?