BIZOMAT MAKEOS · Materials
Brinell Hardness Test Check (Hardness, Validity Rules, Specification)
What Brinell hardness does this indentation give, was the test valid for the specimen thickness, edge distance and spacing, and is the result within specification?
Evaluation of a Brinell test from two perpendicular indentation diameters: mean diameter, hardness, indentation ratio, force–diameter ratio and depth (as the Brinell hardness tool), the approximate tensile strength for steel, and the validity checks against your rules for indentation ratio, least specimen thickness as a multiple of indentation depth, least edge distance and least spacing as multiples of the indentation diameter, and the specification range.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Test force | kgf | Test force in kilograms-force (3000 kgf with a 10 mm ball for steel). |
| Ball diameter | mm | Diameter of the ball. |
| Indentation diameter 1 | mm | Indentation diameter measured in one direction. |
| Indentation diameter 2 (perpendicular) | mm | Indentation diameter measured at right angles. |
| Specimen thickness | mm | Thickness of the specimen under the indentation. |
| Distance from indentation centre to the edge | mm | Distance from the indentation centre to the nearest edge. |
| Distance to the nearest other indentation centre | mm | Distance to the centre of the nearest other indentation. |
| Your rules and specification | ||
| Smallest d ÷ D | Smallest indentation ratio your test standard allows. | |
| Largest d ÷ D | Largest indentation ratio allowed. | |
| Least thickness ÷ depth | Least specimen thickness as a multiple of indentation depth (from your test standard). | |
| Least edge distance ÷ d | Least edge distance as a multiple of the indentation diameter (from your test standard). | |
| Least spacing ÷ d | Least centre spacing as a multiple of the indentation diameter (from your test standard). | |
| Specification minimum | HBW | Lowest hardness the specification allows. |
| Specification maximum | HBW | Highest hardness the specification allows. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Test force
- What it is
- The test force applied to the ball, in kilograms-force as Brinell hardness numbers are defined.
- Units and format
- Enter a number in kgf: kgf. The form accepts 0.000001 kgf to 5000 kgf. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3000 kgf as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- For the same indentation, hardness rises in direct proportion.
- Get it right
- kgf, not N: 1 kgf = 9.807 N.
What this means: Ball diameter
- What it is
- The diameter of the hardmetal ball indenter used for the test.
- Units and format
- Enter a number in mm: millimetres. The form accepts 1 mm to 10 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Indentation diameter 1
- What it is
- The indentation diameter measured across the impression in one direction.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Small reading errors matter: hardness changes faster than the diameter error.
What this means: Indentation diameter 2 (perpendicular)
- What it is
- The indentation diameter measured at right angles to the first; the tool averages the two.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4.02 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Specimen thickness
- What it is
- The thickness of the specimen beneath the indentation, checked against the indentation depth.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Distance from indentation centre to the edge
- What it is
- The distance from the indentation centre to the nearest edge of the specimen.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 12 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Distance to the nearest other indentation centre
- What it is
- The centre-to-centre distance from this indentation to the nearest other indentation.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 14 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Your rules and specification
What this means: Smallest d ÷ D
- What it is
- The smallest indentation diameter ÷ ball diameter that your test standard allows for a valid test.
- Units and format
- Enter a plain number with no unit. The form accepts 0.1 to 0.5. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.24 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Largest d ÷ D
- What it is
- The largest indentation ratio d ÷ D that your test standard allows for a valid test.
- Units and format
- Enter a plain number with no unit. The form accepts 0.3 to 0.9. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.6 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Least thickness ÷ depth
- What it is
- The multiple of the indentation depth that the specimen thickness must reach so the support does not affect the reading.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 20. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 8 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Least edge distance ÷ d
- What it is
- The multiple of the indentation diameter required between the indentation centre and the specimen edge.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 10. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2.5 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Least spacing ÷ d
- What it is
- The multiple of the indentation diameter required between neighbouring indentation centres.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 10. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Specification minimum
- What it is
- The lowest Brinell hardness the drawing or material specification allows.
- Units and format
- Enter a number in HBW: HBW. The form accepts 0 HBW to 800 HBW. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 200 HBW as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Specification maximum
- What it is
- The highest Brinell hardness the drawing or material specification allows.
- Units and format
- Enter a number in HBW: HBW. The form accepts 1 HBW to 800 HBW. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 250 HBW as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Method and formulas
- Mean d = (d₁ + d₂) ÷ 2; HB = 2F ÷ [π D (D − √(D² − d²))]; depth = [D − √(D² − d²)] ÷ 2 (as the Brinell hardness tool).
- Validity: d ÷ D within the limits; thickness ≥ k × depth; edge ≥ k × d; spacing ≥ k × d.
- Approximate tensile strength (steel) ≈ 3.45 HB MPa.
- Example: d = 4.01 mm gives 227.58 HBW (about 785.14 MPa); the test meets the validity rules.
Limitations
- Indentation diameters must be measured accurately; a 1% error gives about 2% in hardness.
- Tensile estimate is approximate and for steels only.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a Brinell result before reporting it
- Choose a load and ball for a thin part
- Screen castings or forgings for hardness
Who it is for
- Test laboratory technicians
- Quality inspectors
- Materials engineers
What you get
- Mean diameter, hardness and depth
- Validity checks
- Specification and tensile estimate
Interpreting the result
- If the indentation is too large or too small for the ball, change the force so that d ÷ D falls in range.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1406–1412. Topic reference; no source tables or recommended settings are reproduced.
- ISO 6506-1 Metallic materials — Brinell hardness test — Part 1: Test method
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Electrical conductivity and what it reveals about a metal
In Eddy-Current Inspection by the Numbers
What it covers: The %IACS scale, why alloying and heat treatment change conductivity, correcting readings to 20 °C, calibrating a conductivity meter, and catching a mislabelled aluminium bar.
Method explained here · BIZOMAT original book
The steel and its transformation
In Induction Hardening by the Numbers
What it covers: What happens inside the steel: austenite, martensite and carbon, why fast heating needs a higher temperature, starting structure, prior austenite grain size, and a bar supplied annealed.
Method explained here · BIZOMAT original book
Inspecting and proving castings
In Metal Casting by the Numbers
What it covers: Showing castings meet their specification: Brinell hardness and its validity rules, X-ray and pressure tests, first-article layout, sampling, and a hardness reading taken too near an edge.
Method explained here · BIZOMAT original book
Graphite shape and nodularity
In Microstructures by the Numbers
What it covers: Describing particle shape with circularity and roundness, measuring nodularity in ductile iron, how section thickness affects it, and checking casting hardness with valid Brinell tests.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
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