Thanks for all of the replies folks. They are appreciated. I believe I didn't make my initial query quite specific enough.
This probably involves more metallurgy than pure physics, but I believe any knife steel alloy consists of lattices of iron and the alloying materials held together by strong bonds. Also in any steel alloy there are impurities such as sulphur which create weaker bonds within the lattices. I'm theorizing that the material is being removed primarily at those weaker impurity bonds rather than at the stronger alloying element bonds??
I enjoyed oxDEADBEAT's reply as he tried to describe what was happening to the lattice at close to the nano scale. Distortion then ripping makes sense. But where does it want to rip? Posting my thread here has helped me refine my thoughts a little more.
You folks have quite a friendly place full of folks that like to explain and assist
I appreciate that and thank you. When I post another question I'll do my best to be more precise.