My experience has been the same as Neeman's with Queen D2. It loses it's fine edge to working sharp quickly then maintains that. "D2 takes a crappy edge, and keeps it forever" being the quip.
Large carbide size and a fine edge has been discussed before and as usual Dave has a well defined, clear answer. It's possible to have both, but a bit difficult.
Dave, what about carbide pull out in use and a fine edge with large carbides. (if that edge has been achieved with the proper abrasive) I would think no biggy from your post, but just to be anal about it. (who me?)
For what it's worth, most of the D2 blades I've used are Queen. These include a stockman (3 blades), Country Cousin (1), and a fixed blade. All of them are finished to something beyond 2000+ grit, which leaves them at essentially mirror by naked eye. They've held up great, with the only touch-up maintenance being done on a denim/fabric hard-backed strop with some AlOx compound (best results with Ryobi White Rouge @ 2-5µ). The edges have been more stable at this finish than most any other steel I've finished similarly, and they've held hair-popping edges very well. In particular, I've liked how these polished edges handle heavy cardboard, and still retain shaving sharpness afterward.
If cutting is degrading quickly with polished edges in Queen's D2, I'd first look at thinning the geometry. Seems counter-intuitive, I know. But geometry is what makes the biggest difference in cutting, especially with shaving sharpness; it's no surprise that razors are ground to ~15° inclusive, for good reason. My thinnest D2 blade is likely the Queen fixed blade (thinned it a LOT, and yes, it took a LONG time), and it has been continually stunning me in the fine edge it takes and holds. All of mine are thinned to 30° inclusive or less, and that fixed blade is somewhat thinner than the rest, at the edge, maybe below 25° inclusive. I've yet to see a rolled edge on any of them, which is notably different than any other of my knives at similar geometry.
BTW, I seem to recall reading that the size of carbides (Chromium, Vanadium) is primarily determined during steel's manufacture, when the carbides form in the first place, as opposed to heat treat, which I assume affects it, but to some lesser degree. There'd be no real advantage to PM manufacturing processes (the goal of which is to reduce their size and minimize segregation, thereby improving distribution), if the carbide size was dependent only on heat treat later on, it seems to me. Queen has been known for the
large carbides in the D2 they use (don't know who manufactures it for them, though). There has been an interesting post, some time back, from someone using vinegar/acid to 'patina' a Queen D2 blade, and the shinier chromium carbides were large enough to see by naked eye, in the pics posted of the blade. I'm convinced it's the larger size of the carbides in those blades, that gives Queen's D2 a reputation for being difficult to refine (but not impossible).
Quoted from Crucible, re: carbide size and distribution in non-PM manufactured steels:
"Effect of Steel Manufacturing on Properties
The maximum practical limit to the amount of carbide-forming elements which may be added to a steel for wear properties depends on the ability to maintain a reasonable distribution of those carbides throughout the steel’s microstructure. When steels are manufactured, they are melted in large batches, containing the desired chemical composition. The batches are poured into ingot molds, and solidify into castings which are subsequently forged or rolled into bars. During the solidification process, the carbides are formed. Under conditions of long slow solidification, these carbides form interconnected “segregated” networks, because they do not stay dissolved in the liquid steel. Large amounts of carbide particles result in more segregation, and thus more non-uniformity in the steel microstructure."
The large (or HUGE) carbide clumps we see in the finished product are the 'segregated networks' of smaller carbides clustered and interconnected together as a result of the non-PM manufacturing process.
David
