EDGE RETENTION/ROLLING PART II

[Jan]

Steel hardness is related to its compressive yield strength which tells us the stress at which steel begins to deform plastically. 

A2 steel hardened to 62 HRC has compressive yield strength some 320 ksi while the same steel hardened to 54 HRC has compressive yield strength only some 250 ksi.

The middle part of the graph posted by KG may be interpreted in the following way:
   
For the blade hardened to 62 HRC the stress generated by the SET roller is probably slightly below the compressive yield strength, while for the blade hardened to 54 HRC the stress generated by the SET roller is probably slightly above the compressive yield strength and so some fraction of the deformation remains permanent. This permanent edge deformation cumulates and causes the observed sharpness decrease for 54 HRC blade.

Jan