Bill Tindall
Apparently (from what I have read, for example Curcible Products web site and the Tribology book, the hard carbides interrupt the plowing action of an abrasive particle causing it to "jump out of the furrow" (those are my words). I am sure you are correct that wide differences in hardness will affect abrasion resistance but apparently a per cent vanadium carbide provides more effect than a few extra points on the Rc scale. If we presume Y-1 and Y-2 , etc. are the same stuff hardened to different values then the LV data confirms that hardness is not a large effect in the range where the steel is used.