Question about metals, ZDP-189 VS ??? and explanations of others...

EOJK... thanks man, that is exactly the article I was referencing. That test is what I've been referring to all along.

Hope that clears things up...

Thanks,
Cleary
 
Just a few things to consider:

Not wanting to deminish the usefulness of real world impressions, but the test cited was somebody doing these cuts buy hand and by feel.

Mr. Glesser was referring to standartized CATRA test which use pretty abrasive silica impregnated cardboard cards as cutting medium. There are not many CATRA machines around since they are very expensive and Spyderco has one in house.

Also, the test that Knife Illustrated was refering to tested blades of vastly different hardness, which has a large impact on the dulling during certain types of cuts and less during other types of cuts (it seems that CATRA tests favor steels with high abrasion resistance). I don't know whether the steels in the tests Mr. Glesser was refering to were of the same or similar hardness.
 
Steel is a common thread and one that brings passion right up to the table. I am an old timer I guess but still like the steels used "then" versus "now." I think D2 is a great blade with little peer to edge holding. ATS 34 is the cousin to 154CM first brought out by Bob Loveless. Great steel. I have had many 440C knives and think it is a very good steel but I do like to know a little about the heat treat on 440C. That may be just me too. I am not caught up with the 420HC craze. It is a steel to be bought in large rolls, stamped out for grinding and is not by almost any test a good edge holding steel. I think using D2 is superior and have the same feelings about ATS and 440C. From my knife making friends, I think S30V must be a really superior steel for knives. Good steels and far above the capability of the user. Can we ask more?
 
TinyDee said:
From my knife making friends, I think S30V must be a really superior steel for knives. Good steels and far above the capability of the user. Can we ask more?
Click to expand...

In my experience S30V doesn't take a very fine edge compared to some other stainless steels like VG-10 or ZDP-189, and it's somewhat prone to chipping, especially if the heat treatment isn't spot on. It's also not a very tough steel, especially not when you compare it to a good carbon steel.

Still, I'd say it's pretty good for a stainless steel, with very good edgeholding and pretty good corrosion resistance. I prefer it over steels like 440c or ATS-34 anytime, but it's not really the wonder steel many people claimed it was when it came onto the market.

Hans
 
HoB said:
...the test cited was somebody doing these cuts buy hand and by feel.
Click to expand...

The reason the results are so dramatically different (CATRA vs the other) is that blunting is not linear, and is similar to an exponential decay, initially rapid and then a plateau. Catra cuts a specific amount of cards and compares sharpness, the other method cuts until a specific level of blunting is achieved and compares the amount of material cut.

If you take two highly nonlinear curves f(x) and g(x), and calculate the ratio g(x)/f(x) at some fixed x, and then solve for what value of g(x) and f(x) = C, the ratio of x values here can be *massively* different than the previous function relationship. This means you can easily say something is 30% better or 200% depending on what exactly you mean.

My problem with some of the tests is that they don't exactly say what they are doing, is it the same geometry with all edges sharpened by the author, or is it different knives with NIB edges, could one be more acute or left more coarse, was one knife even just longer? Were the cuts every repeated to check, could the really low perforamance simply been because of a wire edge?

Some times they make no sense either, consider this one :

ZDP = 3 times VG-10
ZDP = 4 time D2 (at 62 HRC)
ZDP = 10 times ATS-34

So VG-10 is superior to D2 and ATS-34 is not even close to either of them? How do you explain that? This is from a PDF file Willian Henry has on their website.

-Cliff
 
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