Hardness Converter

Convert between Rockwell B, Rockwell C, Brinell, Vickers hardness scales and approximate tensile strength. Based on ASTM E140 conversion tables.

Last updated April 2026

Conversions are approximate per ASTM E140-12b. HRB values apply below ~HRC 20 only. Tensile strength approximations are for carbon and alloy steels. Not valid for non-ferrous metals, austenitic stainless, or other materials with significantly different hardness-strength relationships.

Frequently Asked Questions

How do I convert HRC to Brinell?

Use the ASTM E140 conversion table. For example, HRC 40 equals approximately 371 HB (Brinell, tungsten carbide ball). Direct mathematical conversion is not reliable because the scales measure hardness differently.

What is the difference between HRC and HRB?

HRC (Rockwell C) uses a diamond cone indenter and is used for hard materials like hardened steel (HRC 20-68). HRB (Rockwell B) uses a 1/16 inch steel ball and is used for softer materials like annealed steel and aluminum (HRB 0-100).

What hardness is 4140 steel?

4140 steel hardness depends on heat treatment. Annealed: approximately HRC 18-22 (HRB 87-97). Quenched and tempered: typically HRC 28-35. Oil quenched: up to HRC 54-59.

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