Thanks for the post, Robert. I ordered a set of the files today. I hope to use them on blades I harden in my propane mini-forge.
I’ve always noticed that the stainless knives I’ve sharpened in 420C and 440C “felt” different. Not hard, but resistant to normal abrasion by my diamond stones. I think I’ve sensed something similar on other manual sharpening stones, like the Spyderco Sharpmaker and my Arkansas stones. It’s as if the surface of the steel would rather “smear” than be cut cleanly by the grit. On thinking that over, I wonder if that means that it lends itself more to stropping, which I think is a similar process.
I’m not sure. I’m learning myself and don’t know much about it. I checked Blade HQ where I bought my Launch 1 at and the Rc number for the steel wasn’t mentioned. According to the Kershaw website, their CPM-154 is Rc rated at 58-60. That pretty much goes with my findings with the files. So I’m confident that the files are pretty accurate. I can at least get a reasonable estimate to the hardness of a steel. Being a hobbyist I don’t really need to know the exact Rc number.
Your Japanese is better than mine! Thank you for posting your findings, much like you I collect knives I like and the precise Rc rating is not the determining factor. From the little reading I’ve done, Buck has a proprietary (I believe) hardening procedure that they use on their blades.