David, I have a couple Japanese Kitchen Knives made of Aogami #2, also called Blue #2 steel, rated HRc 63. I did find these knives made of this steel were very easy, and as Mark76 says, very fast, to sharpen and they sharpen to an incredibly sharp and polished edge. This is in comparison to all the different steels I have sharpened, not just hard stainless steels. I liked the Aogami #2 so well, except the reactiveness, that I bought what is supposed to be the next steel that’s slightly better, Aogami Super, also called Super Blue Steel, rated HRc 64. This “Aogami Super” knife sharpens just as easily and takes just as incredibly sharp edge also very quickly and polishes to a mirror bevel easily and very well also.
Bottom line, in my experience, Aogami #2 and Aogami Super are probably the quickest and easiest “hard steel” knives to sharpen, all reactive carbons and all stainless steels included. They sharpen “like butter”! (I own and have experience sharpening probably 15 or 17 different steels and steel alloys)
The only steel I have that on paper is rated as “harder” is a Japanese Kitchen Knife made of ZDP-189 Clad Stainless Steel HRc 65. This stainless steel has all the down falls with carbides you related and is IMO absolutely horrible, difficult, and slow to sharpen. I do believe though, that the same steel, what ever it may be, handled, forged and heat treated by different artisans, forgers or blacksmiths, if you will, will come out differently and may exhibit different qualities and characteristics, and behave differently.
The only reason I can’t call the Aogami steel knives my favorites is their reactivity, (patina), and the slight, off-putting or acidic-like smell, I perceive, when cutting some foods, (food reactivity). Also they do require extra care to keep it from turning and rusting if you like your knifes shiny and reflective. I believe you can treat these steels to create a fixed stable patina then they aren’t so reactive and require little care.
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