Rockwell Hardness Conversion Calculator
Convert between Rockwell hardness scales and other hardness testing standards
What Is Rockwell Hardness?
Rockwell hardness measures a material's resistance to indentation using a standardized indenter and load. Rockwell B (HRB) uses a 1/16-inch steel ball for softer materials; Rockwell C (HRC) uses a diamond cone for harder steels.
Hardness Conversion
Brinell (HB), Vickers (HV), and Rockwell scales cannot be converted with a single universal formula. ASTM E140 and ISO 18265 provide empirical conversion tables for carbon and low-alloy steels. This calculator interpolates standard table values.
$$HR = N - h \cdot d$$For Rockwell B, \(N = 130\) and \(h = 500\). For Rockwell C, \(N = 100\) and \(h = 500\), where \(d\) is indentation depth in mm.
Typical Hardness Ranges
Soft brass: HRB 55–93. Tool steel: HRC 55–66. HRC conversions below about 20 are unreliable; use HRB, HB, or HV for softer materials.
Related tools: Shear Stress Calculator and Shear Modulus Calculator.
Frequently Asked Questions
Are hardness conversions exact?
No. Conversions are approximate and material-specific. ASTM E140 tables apply to carbon and low-alloy steels. Always verify with direct testing for critical applications.
What is the difference between HRC and HRB?
HRC uses a diamond cone indenter for hard materials (typically HRC 20–70). HRB uses a steel ball for softer materials (typically HRB 60–100).
How do I convert HRC 45 to Brinell?
For carbon steel, HRC 45 converts to approximately HB 415 and HV 436 using ASTM E140 table interpolation.
What is Vickers hardness (HV)?
Vickers hardness uses a diamond pyramid indenter. HV values are expressed in kgf/mm² and correlate with other scales through standard conversion tables.
Which standard do these conversions follow?
This calculator uses approximations from ASTM E140-12 hardness conversion tables for non-austenitic steels, consistent with ISO 18265 guidance.
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