Vickers Hardness (HV)
HV = 1.8544 × F / d². Diamond pyramid (136°) indenter; d = mean diagonal (mm). Constant 1.8544 from indenter geometry. Works for all materials from soft to ultra-hard.
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136° diamond pyramid: constant 1.8544 = 2 cos(68°) / sin²(68°) Macro: 30–120 kgf; micro: 0.01–20 kgf Tensile strength ≈ 3.2 × HV (MPa) for steel HV independent of load (for geometrically similar indentations)
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Why: Vickers is universal—one scale for all materials. Preferred for thin films, coatings, and microhardness. More consistent than Brinell due to geometric indenter.
How: Enter applied force (N or kgf) and mean diagonal length (mm). Calculator computes HV, estimates tensile strength (steel), and converts to Rockwell/Brinell.
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For educational and informational purposes only. Verify with a qualified professional.
🔬 Physics Facts
Vickers test (1921): Smith & Sandland; 136° ensures HV ≈ BHN for same material.
— ASTM E384
Microhardness: loads 0.01–1 kgf for thin films and small features.
— ISO 6507
d = (d₁ + d₂)/2; two diagonals measured and averaged.
— Vickers standard
HV 30, HV 50 common macro loads; HV 0.5, HV 1 for micro.
— ASM Handbook
What is Vickers Hardness?
The Vickers hardness test, developed by Robert L. Smith and George E. Sandland in 1921, is one of the most versatile hardness testing methods. It uses a diamond pyramid indenter with a square base and a 136° angle between opposite faces. The test measures the resistance of a material to permanent indentation and is suitable for all materials, from soft metals to ultra-hard ceramics.
Diamond Pyramid
A square-based diamond pyramid indenter creates a square indentation, making measurement more precise than spherical indenters.
Universal Application
Works for all materials from soft (HV < 50) to ultra-hard (HV > 2000), including thin films and coatings.
Microhardness Testing
Low loads (0.01-10 kgf) enable testing of small samples, thin sections, and individual phases in materials.
HV Formula and Calculation
Vickers Hardness Number
F = applied force (N), d = average diagonal length (mm)
The constant 1.8544 comes from the geometry of the 136° diamond pyramid indenter.
Tensile Strength Estimation
More accurate than BHN conversion due to consistent indenter geometry
Standard Test Loads
Macrohardness: HV 30, HV 50, HV 100, HV 120 (30-120 kgf)
Microhardness: HV 0.01 to HV 20 (0.01-20 kgf)
Load selection depends on material hardness and sample thickness.
Microhardness vs Macrohardness
Microhardness (HV < 100)
Test loads: 0.01 - 20 kgf
- Thin samples and coatings
- Small parts and components
- Individual phases in materials
- Surface treatments
- Precision measurements
Macrohardness (HV ≥ 100)
Test loads: 30 - 120 kgf
- Bulk materials
- Standard engineering materials
- Quality control testing
- Material characterization
- Production testing
Hardness Scale Conversions
Vickers hardness can be converted to other scales, though conversions are approximate and material-dependent:
- Rockwell C (HRC): Used for hard materials (HRC 20-70). HRC ≈ (HV - 100) / 5.2
- Rockwell B (HRB): Used for softer materials (HRB 0-100). Less accurate conversion.
- Brinell (BHN): Similar range, uses spherical indenter. BHN ≈ HV / 0.95
- Knoop (HK): Microhardness test with elongated indenter. HK ≈ HV × 0.92
Note: Conversions are approximate and vary with material type. For critical applications, use direct testing on the desired scale.
Material Hardness Ranges
Very Soft (HV < 50)
Pure aluminum, lead, soft plastics. Easy to machine, low wear resistance.
Soft (HV 50-100)
Aluminum alloys, copper, brass. Good machinability.
Medium (HV 100-200)
Mild steel, stainless steel, titanium. Good balance of properties.
Hard (HV 200-400)
Hardened steel, tool steel, titanium alloys. High wear resistance.
Very Hard (HV 400-800)
Hardened tool steel, high-speed steel. Cutting tool grade.
Extremely Hard (HV > 800)
Carbides, ceramics, coatings. Ultra-hard materials.
Advantages of Vickers Hardness Testing
Universal Applicability
Works for all materials from soft metals to ultra-hard ceramics, unlike Rockwell which has limited ranges.
Consistent Geometry
Diamond pyramid maintains same shape regardless of load, providing consistent results across hardness ranges.
Microhardness Capability
Low loads enable testing of thin films, coatings, small parts, and individual phases in materials.
Precise Measurement
Square indentation with two diagonals provides more accurate measurement than circular indentations.
Test Procedure and Best Practices
- Sample Preparation: Ensure flat, polished surface free from scale, oxide, or contamination.
- Load Selection: Choose appropriate load based on material hardness and sample thickness. For thin samples, use microhardness loads.
- Indentation: Apply load for specified dwell time (typically 10-15 seconds for macrohardness, 10-30 seconds for microhardness).
- Measurement: Measure both diagonals of the square indentation using calibrated microscope. Average the two measurements.
- Spacing: Maintain minimum spacing of 2.5× diagonal length between indentations to avoid interaction effects.
- Edge Distance: Keep indentations at least 2.5× diagonal length from sample edges.
- Multiple Tests: Perform at least 3-5 indentations and average results for accuracy.
Frequently Asked Questions
What is the Vickers hardness test and how does it work?
The Vickers hardness test uses a diamond pyramid indenter with a square base and 136° angle. A known force is applied, creating a square indentation. The diagonals are measured, and HV is calculated as HV = 1.8544 × F / d², where F is force in N and d is average diagonal in mm.
What is the difference between microhardness and macrohardness?
Microhardness uses loads from 0.01-20 kgf and is used for thin samples, coatings, and small parts. Macrohardness uses loads from 30-120 kgf for bulk materials. The boundary is typically around 100 HV, though load selection depends on sample thickness and hardness.
How accurate are hardness scale conversions?
Conversions between hardness scales (HV, HRC, BHN, HK) are approximate and material-dependent. For critical applications, always test directly on the desired scale. Conversions are most accurate for similar materials and within similar hardness ranges.
Can Vickers hardness predict tensile strength?
Yes, for steel, tensile strength ≈ 3.2 × HV (MPa). For aluminum, use ≈ 2.6 × HV, and for copper alloys, ≈ 2.9 × HV. These are approximations; actual strength depends on material composition, heat treatment, and other factors.
What test load should I use for my material?
For macrohardness (HV ≥ 100), use 30-120 kgf loads. For microhardness (HV < 100), use 0.01-20 kgf. Select load so indentation diagonal is 0.02-0.5 mm for macrohardness, or 0.01-0.1 mm for microhardness. Ensure sample thickness is at least 10× the indentation depth.
Why do I need to measure both diagonals?
Measuring both diagonals ensures accuracy and detects anisotropy or test errors. If diagonals differ by more than 5%, the test may be invalid. The average diagonal is used in calculations. Consistent diagonal measurements indicate uniform material properties.
What materials can be tested with Vickers hardness?
Vickers hardness works for all materials from soft metals (HV < 50) to ultra-hard ceramics (HV > 2000). It's universal unlike Rockwell which has limited ranges. It's particularly useful for thin films, coatings, small parts, and materials with varying hardness.
How does Vickers hardness relate to wear resistance?
Higher Vickers hardness generally indicates better wear resistance, though toughness and microstructure also matter. Hard materials (HV > 400) resist abrasion well but may be brittle. For wear applications, consider both hardness and toughness.
📚 Official Data Sources
⚠️ Disclaimer
Testing Disclaimer: This calculator provides estimates based on standard Vickers hardness formulas (ASTM E92). Actual hardness values depend on material composition, heat treatment, surface preparation, test conditions, and operator skill.
Conversion Accuracy: Hardness scale conversions are approximate and material-dependent. For critical applications, always perform direct testing on the desired scale. Conversions may vary by ±5-10% depending on material type.
Material Properties: Tensile strength estimates are approximations. Actual strength depends on many factors including grain size, heat treatment, manufacturing processes, and environmental conditions. Always use certified material test data for critical designs.
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