Indentation hardness
Hardness measurements quantify the resistance of a material to plastic deformation. Indentation hardness tests compose the majority of processes used to determine material hardness, and can be divided into two classes: "microindentation" and "macroindentation" tests. Microindentation tests typically have forces less than . Hardness, however, cannot be considered to be a fundamental material property. Classical hardness testing usually creates a number which can be used to provide a relative idea of material properties. As such, hardness can only offer a comparative idea of the material's resistance to plastic deformation since different hardness techniques have different scales.
Surface roughness
Each of the roughness parameters are calculated using a formula for describing the surface. Standard references that describe each in detail are Surfaces and their Measurement.
There are many different roughness parameters in use, but formula_1 is by far the most common, though this is often for historical reasons and not for particular merit, as the early roughness meters could only measure formula_1. Other common parameters include formula_3, formula_4, and formula_5. Some parameters are used only in certain industries or within certain countries. For example, the formula_6 family of parameters is used mainly for cylinder bore linings, and the "Motif parameters" are used primarily in the French automotive industry. The MOTIF method provides a graphical evaluation of a surface profile without filtering waviness from roughness. A "motif" consists of the portion of a profile between two peaks and the final combinations of these motifs eliminate ″insignificant″ peaks and retains ″significant″ ones. Please note that formula_1 is a dimensional unit that can be micrometer or microinch.