Test Forces and Indenters

Test Forces

There are two general classifications of the Rockwell test: the Rockwell hardness test and the Rockwell superficial hardness test. The significant difference between the two test classifications is in the test forces that are used. For the Rockwell hardness test, the preliminary test force is 10 kgf (98N) and the total test forces are 60 kgf (589 N), 100 kgf (981 N), and 150 kgf (1471 N). For the Rockwell superficial hardness test, the preliminary test force is 3 kgf (29 N) and the total test forces are 15 kgf (147 N), 30 kgf (294 N), and 45 kgf (441 N).

Indenters

The standard Rockwell indenters are either diamond conical indenters or tungsten carbide balls of 1.588 mm (1/16 in.), 3.175 mm (1/8 in.), 6.350 mm (1/4 in.), or 12.70 mm (1/2 in.) in diameter. Previous editions of ASTME 18 have stated that the steel ball was the standard type of Rockwell indenter ball. The tungsten carbide ball indenter is now the standard indenter to be used for the Rockwell ball scales. Steel indenter balls may be used only for testing thin sheet tin mill products as specified in ASTMA 623.