TABLE OF CONTENTS Hardness tests are a quick and simple method to characterise a metal's resistance to deformation and can in some cases be related to an equivalent yield strength. A number of different hardness tests exist, which differ in the type of indenter used, the load applied, and the means used to quantify the extent of permanent deformation. Further information concerning the hardness of metals and hardness testing may be found in Refs [1-3]. Hardness values for some common metals and alloys are given in Chapter 22.
Relevant standards: ASTM E10-01, BS EN 10003-1:1996
An indenter comprising a hardened steel ball of diameter D mounted in a suitable holder is pushed into the material under test by a force F. The diameter of the indentation left in the surface of the material after removal of the load is measured in two directions at right angles. The area of the curved surface of the indentation is calculated from the mean diameter, d, the indentation being considered as a segment of a sphere of diameter D. The Brinell hardness is the quotient obtained by dividing the load, symbol f, expressed in kilograms-force, by the surface area of the indentation expressed in square millimetres.
Symbols:
| F | = force (N) |
| f | = load symbol (kgf) |
| D | = diameter of ball in millimetres (mm) |
| d | = mean diameter of indentation in millimetres (mm) |
The symbol HBW is supplemented by numbers indicating the diameter of the ball...
