Convert Rockwell C (HRC) hardness to other common hardness scales and estimate tensile strength for steel.
Last updated: March 2026 | By ForgeCalc Engineering
The Rockwell hardness test is a common method for measuring the hardness of a material. It works by measuring the depth of penetration of an indenter (either a diamond cone or a steel ball) under a specific load.
The Rockwell C scale (HRC) is specifically used for hard materials like steel, using a diamond indenter and a 150 kgf load. Other scales like Rockwell B (HRB) are used for softer materials. Hardness is often closely correlated with other mechanical properties like tensile strength.
Diamond cone indenter. Standard for hardened steels and tool steels.
Hardened steel or carbide ball indenter. Good for cast iron and non-ferrous metals.
Diamond pyramid indenter. Used for very thin materials or small areas.
Different materials have vastly different hardness levels. A diamond indenter used for HRC would shatter if used on soft lead, and a steel ball used for HRB wouldn't leave a mark on hardened tool steel.
No, but they are related. Hardness measures resistance to indentation, while strength measures resistance to deformation or failure. For steel, hardness is a very good predictor of tensile strength.
It's a process where only the outer surface of a part is hardened (e.g., to HRC 60) while the core remains soft and tough. This is common in gears and shafts.
Conversions are empirical and material-specific. A conversion table for steel will not work for aluminum or plastic. Always use the scale specified by the material standard when possible.
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