Relatively new entry in the steel database, Microtech announced that circa 01/2023. Described as a tweak on the original Bohler-Uddeholm M390 PM steel, it has no official composition published, but based on the data, no real reason to thin k it has something outside of the M390 steel specs.
Relatively recent steel, YTL8 is produced by EST. Some sort of modification of the popular AISI D2 Tool Steel.
New steel, took some time to find the data, used only by Russian makers, and despite its AUS name it isn't an Aichi steel, but from a Chinese maker Steel Import Co. Not quite sure about the rest of the claims about it either.
Small/Medium folder. Definitely high end and very well made, with premium materials throughout, handle Bead Blasted 6Al4V Titanium Alloy, blade - Bohler-Uddeholm M390 Steel, anodized screws, CF inlays, you name it. Still, it is a one tough little folder, and very capable of cutting. Maintenance is very easy, that is keeping it sharp, not so sure about keeping it scratch free, but it's a user, not a safe queen.
One of the rare occasions when a knife steel is actually designed for knives :) And by Larrin from KnifeSteelNerds.com too. Detailed info in the link, but in short very interesting alloy with some amazing properties, designed for knives by true knife enthusiast.