Brinell Hardness Number
Calculate Brinell hardness number (HBW) from applied load, ball diameter, and indentation diameter using the ISO 6506-1 standard formula with comparison charts.
About This Calculator
The Brinell Hardness Number (HBW) Calculator computes the indentation hardness of a material specimen using data from a standard Brinell hardness test as defined by ISO 6506-1. This non-destructive test presses a hardened steel or tungsten carbide ball of known diameter D into the material surface under a controlled load P, then measures the resulting indentation diameter d. The calculator applies the formula HBW = 0.102 × 2P / (πD(D − √(D² − d²))) to determine the Brinell hardness number in megapascals (MPa). Engineers, metallurgists, quality control technicians, and materials science students use this value to assess material strength, wear resistance, and conformity to specifications across industries including automotive, aerospace, construction, and manufacturing.
The Brinell hardness test was invented by Swedish engineer Johan August Brinell in 1900 and remains one of the most widely used hardness testing methods. Unlike Rockwell or Vickers tests which use different indentor geometries, the Brinell test uses a spherical indentor that produces a relatively large indentation, making it ideal for materials with non-uniform grain structures such as cast iron, forgings, and non-ferrous alloys. The 0.102 factor in the formula converts the applied load from Newtons to kilogram-force (kgf), preserving compatibility with traditional Brinell hardness scales while using modern SI units for the test force.
Material Hardness Reference
The chart below compares your calculated Brinell hardness number against typical values for common materials: pure aluminum (15 HB), copper (35 HB), AW-6060 aluminum alloy (75 HB), mild steel (130 HB), hardened steel (450 HB), and glass (1550 HB). These reference values help contextualize your result and provide a quick check for reasonableness. Note that actual hardness depends on alloy composition, heat treatment, cold working, and testing conditions.
Test Parameters
Standard Brinell tests typically use a 10 mm ball diameter with loads ranging from 500 kgf (4903 N) for soft metals to 3000 kgf (29420 N) for steel and iron. The test force is maintained for 10-15 seconds (longer for creep-sensitive materials). For accurate results, the indentation diameter should be measured in two perpendicular directions and averaged, and the test surface must be clean, smooth, and free of oxide layers.
Frequently Asked Questions
What is the Brinell hardness number (HBW)?
The Brinell hardness number (HBW) is a measure of indentation hardness obtained by pressing a hardened steel or tungsten carbide ball of diameter D into the material surface under a known load P, then measuring the diameter d of the resulting indentation. The formula is HBW = 0.102 × 2P / (πD(D − √(D² − d²))).
How do I perform a Brinell hardness test?
To perform a Brinell hardness test per ISO 6506-1: bring the indentor ball into contact with the test surface, apply the test force perpendicularly without shock, maintain the force for 10-15 seconds, remove the load, measure the indentation diameter in two perpendicular directions, and use the formula to calculate HBW.
What is the difference between Brinell, Vickers, and Rockwell hardness tests?
Brinell uses a ball indentor (typically 10 mm) and is best for coarse-grained or heterogeneous materials like cast iron. Vickers uses a diamond pyramid indentor for micro-hardness testing of thin sections and small parts. Rockwell uses either a diamond cone or steel ball and measures depth of indentation for quick, direct-read testing across multiple scales.
What are typical Brinell hardness values for common materials?
Typical Brinell hardness values: pure aluminum 15 HB, copper 35 HB, AW-6060 aluminum 75 HB, mild steel 130 HB, hardened steel 450 HB, and glass 1550 HB. These values vary with material composition, heat treatment, and processing conditions.
Why is the factor 0.102 used in the BHN formula?
The factor 0.102 (which is 1/9.80665) converts the applied load from Newtons to kilogram-force (kgf). The traditional Brinell formula uses kgf, so when the load P is measured in Newtons as per SI standards, multiplying by 0.102 gives the equivalent value in kgf for the hardness calculation.
Can the Brinell hardness test be used for all materials?
The Brinell test is best suited for materials with coarse or heterogeneous grain structures like cast iron, non-ferrous alloys, and steel. It is not recommended for very hard materials (above 650 HBW) as the ball indentor may deform, nor for very thin surface layers where micro-indentation tests like Vickers or Knoop are more appropriate.
How does the indentation diameter affect the Brinell hardness number?
The Brinell hardness number is inversely related to the indentation diameter — a smaller indentation under the same load indicates higher hardness. The relationship is non-linear because the formula involves the square root term √(D² − d²), so even small changes in d significantly affect the result when d approaches D.
What standard governs the Brinell hardness test?
The Brinell hardness test is governed by international standard ISO 6506-1: Metallic materials — Brinell hardness test — Part 1: Test method. In the United States, ASTM E10 covers the standard test method for Brinell hardness of metallic materials.