Hardness measurement from empiricism to metrology an application to Rockwell C scale

Some limits of the present definition of hardness scales are examined. The experimental analysis performed for Rockwell C hardness scale shows the sensitivity to the time (due to material creep) and to the strain rate, requiring a further definition of other parameters to keep these phenomena under control. As the definition of correct time intervals for minor load and total load depends on the plastic performance of the material tested itself, a new proposal using creep as check condition is given.