Whats the minimum and the maximum size of the ball indenter?
The standard tungsten carbide or silicon nitride indenters are offered in the following sizes: 0.25-mm (0.010 inch) diameter, 0.51-mm (0.020 in) diameter, 0.76-mm (0.030 in) diameter, and 1.57-mm (0.062 in) diameter. The minimum and maximum size indenters are 0.051-mm radius and 7.50-mm radius. It should be noted that the grain size of the metallic test material will impose limitations on the choice of a suitable small size indenter in order to obtain macroscopic stress-strain curve (e.g. at a very small indentation depth, a 0.25-mm diameter indenter covers only three grains of a carbon steel material with a 20 microns of a meter grain size). Also, large size indenters will require higher indentation loads. For the same maximum indentation strain (or approximately the same percentage of indenter radius pushed into the test surface), doubling or tripling the indenter will result in 4 and 9 times the maximum indentation load, respectively. top 5. To determine yield stress, one needs the
