Hardness Unit Conversion

Convert between Rockwell (HRA, HRB, HRC, HRD), Brinell (HBS, HBW), Vickers (HV), Shore (HS), and tensile strength. Based on ASTM E 140, with linear interpolation for intervals.

Rockwell A (HRA)

HRA

Rockwell B (HRB)

HRB

Rockwell C (HRC)

HRC

Rockwell D (HRD)

HRD

Superficial Rockwell 15N

HR15N

Superficial Rockwell 30N

HR30N

Superficial Rockwell 45N

HR45N

Brinell (HBS)

HBS

Brinell (HBW)

HBW

Vickers (HV)

HV

Shore (HS)

HS

Tensile Strength (TS, MPa)

MPa

Unit Conversion Relations

Rockwell, Brinell, Vickers, Shore, and tensile strength conversion based on ASTM E 140 standard.
Interval values use linear interpolation.
For detailed reference, see ASTM E 140 or related standards.

FAQ

What is the difference between Rockwell, Brinell, and Vickers hardness tests?
Rockwell uses a diamond cone or steel ball with specific loads and measures penetration depth. Brinell uses a hardened steel ball with heavy loads and measures indentation diameter. Vickers uses a diamond pyramid and measures diagonal length. Each method suits different materials and hardness ranges.
Which hardness scale should I use for my material?
HRC (Rockwell C) for hardened steels (20-70 HRC), HRB (Rockwell B) for softer steels and non-ferrous metals (20-100 HRB), HV (Vickers) for thin materials and coatings, HBS/HBW (Brinell) for castings and forgings. Choose based on material type and expected hardness range.
How accurate are hardness conversions between different scales?
Conversions are approximations based on ASTM E 140 standard correlations. They're most accurate within the recommended ranges for each scale. Direct measurement is always preferred over conversion, especially for critical applications or when precise values are required.
What is the relationship between hardness and tensile strength?
For carbon and low-alloy steels, there's an approximate relationship: Tensile Strength (MPa) ≈ 3.45 × HB (Brinell). However, this varies with material composition, heat treatment, and microstructure. The calculator provides estimates based on established correlations.
Why are there so many different hardness scales?
Different scales were developed for specific applications and material types. Each test method has advantages: Rockwell is fast and leaves small indentations, Brinell works well for coarse-grained materials, Vickers is versatile for thin sections, and Shore is used for elastomers and plastics.
What are typical hardness values for common materials?
Soft aluminum: 20-40 HB, mild steel: 120-200 HB, hardened tool steel: 50-65 HRC, stainless steel: 150-300 HB, cast iron: 150-300 HB. These values help identify materials and verify heat treatment effectiveness in quality control processes.