The Rockwell C scale is used only on hard metals.

The Rockwell C scale is used only on hard metals.

• A. True
• B. False
• C. Not used
• D. Used for soft metals

Answer: (A)

Rockwell C is the scale designed for hard materials. It uses a diamond cone indenter and a relatively heavy major load, which creates a precise, shallow indentation in hard metals like hardened steels and tool steels. Because of this setup, measurements are most reliable on materials that resist deformation, i.e., hard metals. Soft metals would penetrate more easily and yield readings that are less accurate or fall outside the useful range, so they’re typically tested with other scales that use different indenters and loads. That’s why this statement is true: the Rockwell C scale is used for hard metals and is not appropriate for soft metals.

Rockwell C is the scale designed for hard materials. It uses a diamond cone indenter and a relatively heavy major load, which creates a precise, shallow indentation in hard metals like hardened steels and tool steels. Because of this setup, measurements are most reliable on materials that resist deformation, i.e., hard metals. Soft metals would penetrate more easily and yield readings that are less accurate or fall outside the useful range, so they’re typically tested with other scales that use different indenters and loads. That’s why this statement is true: the Rockwell C scale is used for hard metals and is not appropriate for soft metals.