The unit of hardness, particularly the SI unit, is N/mm² (Newtons per square millimeter).
Understanding Hardness Units
Hardness is a material property that describes its resistance to localized plastic deformation, such as indentation or scratching. Unlike properties like pressure, which also uses related units, hardness measurements are specific to the testing method used.
Based on the provided information:
- The SI unit for hardness is N/mm².
- The unit Pascal (Pa), which is equivalent to N/m², is also used for hardness measurements.
- It is crucial not to confuse hardness with pressure, despite the units being related.
- Different types of hardness tests (such as Brinell, Vickers, Rockwell) have their own specific scales of measurement, even though the underlying units might relate to force per area (like N/mm² or Pa).
Units Used for Hardness
Here are the primary units mentioned in the reference:
- N/mm² (Newtons per square millimeter) - Cited as the SI unit.
- Pascal (Pa) - Also used, equivalent to N/m².
It's important to remember that while these fundamental units apply, specific hardness values are often reported using the scale name (e.g., HV for Vickers Hardness, HRC for Rockwell C Scale) which incorporates the test method and calculations derived from force and indentation area, ultimately related to force per unit area.
