In what situations should a surface Rockwell hardness test be used instead of a Rockwell hardness test?

When encountering thinner materials, smaller specimens, shallower surface hardened layers, or when testing surface coatings, the superficial Rockwell hardness test should be used instead. In this case, by using the same indenters as the Rockwell hardness test and employing test forces of 15kg, 30kg, and 45kg, effective hardness test results can be obtained on the aforementioned specimens.