Since edge stability is being thrown around again, I'll relapse once again to a discussion of it.
I've looked and discussed here, and done many searches looking for a source that will define "edge stability" to me, but have not found the term used in industrial or engineering literature, just knife sites.
I know Mr. Landes tested it by placing an unknown force perpindicular to an razor thin yet otherwise undefined edge using unknown means (a hardened steel sphere of "x" diameter?). The results as far as I can figure were obtained by magnified visual observation of the edge afterwards. Not sure how the visual observation was made or quantified.
I imagine you would see some steels that would not accept the base test edge standard (very thin geometry and max 1 micron diameter edge?), others that chip with little edge deformation, some that chip with large edge deformation, and others that would hardly chip and just deform, so you would have to figure out how to quantify or rank those defects on an equal basis (this is a three dimensional problem, so some sticklers would have issue with just a two dimensional observation/measurement).
I wonder how much of this measurement is determined by the suitability of a steel to cut at razor type geometry, how much by tensile strength of the steel, how much by the ductility, and can't see how the test measures the sharpenability of the steel. I'm certain these questions are addressed in his book, and I would venture the concept has been mangled and mischaracterized here in the past. I suspect that if the steel would not accept an extremely fine and sharp edge, Landes figured it out before the test started. The test itself would help you determine the ability of those steels that made it to your test baseline condition to withstand lateral forces. How you relate that to other characteristics that are important to knife performance is another issue.
Grain size, carbide volume, avg carbide size, matrix properties, and undoubtedly other characteristics play a part in determining it, and to conjecture is natural, but to really know how it rates it has to be tested.
Would it be just as, or more, applicable to the average knifenut to do the test with a larger lateral load on a geometry closer to the average knife geometry? It would be interesting, anyway.
In the absence of any adequate definition, these conversations would be more meaningful to me if the relative performance (ability to take a thin edge, ability to take a sharp edge, etc.) were compared to real and practically measurable characteristics (grain size, carbide volume, avg size of carbides, etc.) rather than a characteristic that is only defined by one book printed in German and has never been defined adequately here (or any other English website that I can find).
If I knew the particulars of the test, it would be interesting to discuss how the results are relatable to the characteristics we know affect it. Does one of the characteristics always trump another? Does grain size always rule given a steel within a range of carbide volumes, or when can other characteristics like carbide size or matrix strength start to really affect edge stability? It is pointless to have these conversations until we have more information.
Man, I don't know why I wasted all that time writing all that on such a beautiful day here - see ya, I'm going outside!
