rockwell+hardness+test

=rockwell hardness test=

NOTE: You will be required to carry out Rockwell tests in the Laboratory.
There are several Rockwell scales available. The most common ones used are the B and C scales Spherical tip 0.2mm radius || Harder steels (tempered), titanium and case-hardened steel ||
 * Scale || Abbreviation || Load || Indenter || Use ||
 * B || HRB || 100kgf || 1.588mm (1 ⁄ 16-inch) diameter steel sphere || Aluminium, brass, bronze, copper and soft steels (untempered) ||
 * C || HRC || 150kgf || 120° diamond cone (brale)

Procedure
Ensure metal surface is smooth, clean and free of oxidised layers.Both flat and curved (round bar) surfaces can be used. Firstly a minor load is applied which breaks through any slight surface roughness. Hence minimal surface preparation is required. This process increases accuracy as it also eliminates the effect of backlash in the system. A zero datum position is achieved with this first load for the penetration depth i.e. return the gauge to zero for the appropriate scale, either B or C. A major load is then applied until the dial needle comes to rest, in about three to five seconds. The resulting hardness value is read directly from the needle on the circular dial. The hardness value is derived from the penetration depth (difference) from the major load. The entire procedure is quick and should only take about 30 seconds.

Indenting forces
 * = Scale ||||= Preliminary force ||||= Additional force ||||= Total force ||
 * =  ||= N ||= kg ||= N ||= kg ||= N ||= kg ||
 * = B ||= 98 ||= 10 ||= 882 ||= 90 ||= 980 ||= 100 ||
 * = C ||= 98 ||= 10 ||= 1372 ||= 140 ||= 1470 ||= 150 ||

Presenting results Hardness value is presented first, then the letters HR to indicate Rockwell harness test followed by the scale used e.g.

60 HR C
View the following =Rockwell indentation hardness test procedure=