BIZOMAT MAKEOS · Materials
Vickers Hardness Test Check (Hardness, Validity, Specification)
What Vickers hardness do these indentation diagonals give, was the test valid for the thickness, spacing and edge distance, and is the result within specification?
Evaluation of a Vickers hardness test from two indentation diagonals: mean diagonal, hardness HV and indentation depth, the least specimen or layer thickness of 1.5 diagonals (as the Vickers–Knoop hardness tool), the difference between the diagonals, and checks of thickness, edge distance and spacing as multiples of the diagonal (your rules), diagonal difference 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 (HV10 = 10 kgf). |
| Diagonal 1 | mm | First diagonal of the indentation. |
| Diagonal 2 | mm | Second diagonal, at right angles. |
| Specimen or layer thickness | mm | Thickness of the specimen or of the hardened layer tested. |
| Indentation centre to edge | mm | Distance from the indentation centre to the nearest edge. |
| Indentation centre to the next | mm | Distance to the centre of the nearest other indentation. |
| Your rules and specification | ||
| Least edge distance ÷ diagonal | Least edge distance as a multiple of the mean diagonal (from your test standard). | |
| Least spacing ÷ diagonal | Least spacing as a multiple of the mean diagonal (from your test standard). | |
| Largest difference between diagonals | % | Largest difference between the two diagonals you accept (a larger difference suggests a tilted surface). |
| Specification minimum | HV | Lowest hardness the specification allows. |
| Specification maximum | HV | 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 load pressed onto the diamond pyramid indenter during the test, as named in the scale (HV10 means a test force of ten kilograms-force).
- Units and format
- Enter a number in kgf: kgf. The form accepts 0.001 kgf to 120 kgf. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 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 diagonals, hardness is directly proportional to the test force.
- Get it right
- This tool works in kgf, not newtons; 1 kgf = 9.80665 N.
What this means: Diagonal 1
- What it is
- The first corner-to-corner diagonal of the square indentation, measured on the hardness tester’s microscope or image system.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.3 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Hardness falls with the square of the mean diagonal, so small reading errors matter.
- Get it right
- Type millimetres; microscope readings are often shown in µm (divide by 1000).
What this means: Diagonal 2
- What it is
- The second diagonal of the same indentation, 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 5 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.302 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- A large difference from the first diagonal usually means the surface is tilted or not flat.
What this means: Specimen or layer thickness
- What it is
- The thickness of the test piece, or of the hardened or coated layer being tested, under the indentation. It is compared with one and a half mean diagonals.
- 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 0.6 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- For a case-hardened or coated part, use the layer thickness, not the whole part.
What this means: Indentation centre to edge
- What it is
- The distance from the centre of the indentation to the nearest edge of the test piece, measured on the surface.
- 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 1 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Measure from the indentation centre, not from its corner.
What this means: Indentation centre to the next
- What it is
- The distance from the centre of this indentation to the centre of the nearest other indentation on the same surface.
- 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 1.2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Measure centre to centre, not the gap between the indentation edges.
Your rules and specification
What this means: Least edge distance ÷ diagonal
- What it is
- The smallest edge distance your test standard allows, written as a multiple of the mean diagonal. The tool multiplies it by the diagonal and compares it with the measured edge distance.
- 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.
- Get it right
- Take the multiple from the test standard you work to; it can differ for different materials.
What this means: Least spacing ÷ diagonal
- What it is
- The smallest centre-to-centre spacing between indentations that your test standard allows, written as a multiple of the mean diagonal.
- 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.
- Get it right
- Take the multiple from your test standard; it can differ from the edge distance multiple.
What this means: Largest difference between diagonals
- What it is
- The largest difference between the two diagonals you accept, as a percentage of the mean diagonal. A larger difference points to a tilted or uneven surface.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 0.1% to 50%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 5% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- It is a percentage of the mean diagonal, not a length.
What this means: Specification minimum
- What it is
- The lowest Vickers hardness the drawing or material specification allows for this part or layer.
- Units and format
- Enter a number in HV: HV. The form accepts 0 HV to 3000 HV. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 180 HV as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the limit for the same test force scale as the test, as written on the specification.
What this means: Specification maximum
- What it is
- The highest Vickers hardness the drawing or material specification allows for this part or layer.
- Units and format
- Enter a number in HV: HV. The form accepts 1 HV to 3000 HV. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 230 HV as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- It must be above the specification minimum.
Method and formulas
- Mean diagonal d = (d₁ + d₂) ÷ 2; HV = 1.8544 F ÷ d²; depth ≈ d ÷ 7; least thickness = 1.5 d (as the Vickers–Knoop hardness tool).
- Validity: edge ≥ k × d; spacing ≥ k × d; diagonal difference = |d₁ − d₂| ÷ d.
- Specification: HV within the limits.
- Example: d = 0.301 mm gives 204.68 HV10; the test meets the validity rules.
Limitations
- Diagonal measurement accuracy dominates at low loads.
- Rules for thickness, spacing and edge distance differ between standards and materials.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a Vickers result before reporting it
- Check whether a thin case or coating can be tested
- Screen heat-treated parts for hardness
Who it is for
- Test laboratory technicians
- Quality inspectors
- Materials engineers
What you get
- Mean diagonal, hardness and depth
- Validity checks
- Specification check
Interpreting the result
- If the layer is too thin for the load, use a lower force so the indentation stays within the layer.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1406–1412. Topic reference; no source tables or recommended settings are reproduced.
- ISO 6507-1 Metallic materials — Vickers 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
Sorting steel parts by permeability and hardness
In Eddy-Current Inspection by the Numbers
What it covers: Comparator sorting of steel parts with an encircling coil, separating hardened from unhardened shafts, what overlapping populations do to a threshold, and a new bar supplier's shifted signals.
Method explained here · BIZOMAT original book
Measuring case depth
In Induction Hardening by the Numbers
What it covers: How case depth is measured and judged: sectioning, a Vickers hardness traverse, the validity of each indentation, effective case depth by interpolation, and an indentation too close to the surface.
Method explained here · BIZOMAT original book
Heat flow, interaction time and hardened cut edges
In Laser Processing by the Numbers
What it covers: How interaction time and heat conduction set the power density a cut needs and the width of the heated zone, and how to find and avoid hardened laser-cut edges in steel.
Method explained here · BIZOMAT original book
Hardness traverses and microhardness
In Microstructures by the Numbers
What it covers: Measuring a hardened case with a microhardness traverse, keeping indentations valid, finding the effective hardened depth, and how diagonal measurement uncertainty limits the result.
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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