The Rockwell hardness test is used to test the hardness of materials. The Rockwell test is usually performed on metals ranging from thin steal all the way to harder metals like Titanium. However, there are multiple scales to test in and these are identified by a letter ranging from A-V Each scale uses a different indenter and load to perform the test.
The equation for the Rockwell hardness test for metals is below: d=depth from zero load point. N and s = various scale factors that can be found in the chart below.
Rockwell A scale
Used to test: Tungsten carbide.
Rockwell B Scale
Used to test: aluminum, brass, and softer steels
Rockwell C Scale
Used to test: harder steels.
There are other scales that are associated with a Rockwell superficial test. These scales use a lighter loads and shallow impressions to perform the test. These are used on testing very thin metals.
Ames Superficial Hardness Tester
Note: There is only one row of dial numbers for the Ames superficial tester.