Rockwell Hardness Test
Test designed to measure the hardness of the fastener, based on an alphabetical-numerical scale. The higher the number, the harder the fastner.
Rockwell tests are utilized to test for decarburization and carburization and to determine the amount of resistance to permanent deformation during the testing procedure. They also assure that heat treating was performed to specification.
ASTM standards require socket screw products meet specific Rockwell Hardness Standards. Socket screws are typically in the “C” scale, which is the hardest Rockwell designation, but the scale designation is dependent on the size of the socket screw.