ABSTRACT
For instance, the model proposed by Lawn and Howes [1] is based on (a) the premise that the loading is elastic-plastic while the unloading is purely elastic and (b) the recognition that a residual field term must be taken into consideration to accommodate the postindentation permanent deformation, which makes a significant departure from the initial, flat test surface. They predicted that the relationship is:
( )
= − α − ν
W W
H
E 1 2 tan
(12.3)
where α is the semi-apex angle of the indenter. This relationship was successfully applied to Vickers microindentation hardness of soda lime glass, pyroceram, hot-pressed silicon nitride, tungsten carbide, steel, etc.
