Vickers Hardness Number Calculator

Calculate material hardness using Vickers test method

Enter the test load and diagonal measurements to determine the Vickers Hardness Number (HV) of your material sample.

Example Calculations

Common Vickers hardness test scenarios

Mild Steel

Steel

Standard mild steel hardness test with 10 kgf load

Test Load: 10 kgf

First Diagonal: 0.145 mm

Second Diagonal: 0.148 mm

Material Type: Steel

Aluminum Alloy

Aluminum Alloy

Aluminum alloy testing with 5 kgf load

Test Load: 5 kgf

First Diagonal: 0.185 mm

Second Diagonal: 0.187 mm

Material Type: Aluminum

Titanium Grade 5

Titanium Grade 5

Titanium alloy hardness measurement

Test Load: 20 kgf

First Diagonal: 0.125 mm

Second Diagonal: 0.127 mm

Material Type: Titanium

Ceramic Material

Ceramic Material

High hardness ceramic testing

Test Load: 50 kgf

First Diagonal: 0.085 mm

Second Diagonal: 0.087 mm

Material Type: Ceramic

Other Titles
Understanding Vickers Hardness Number: A Comprehensive Guide
Master the principles and applications of Vickers hardness testing

What is Vickers Hardness Testing?

  • Definition and Principles
  • Historical Development
  • Test Methodology
The Vickers hardness test is a standardized method for measuring the hardness of materials using a diamond pyramid indenter. Developed by Robert L. Smith and George E. Sandland at Vickers Ltd. in 1921, this test provides a universal hardness scale that can be applied to any material regardless of its hardness.
Test Principle
The test involves pressing a square-based diamond pyramid indenter into the material surface under a specific load. The resulting indentation is a square impression with diagonals that are measured to calculate the hardness value. The Vickers Hardness Number (HV) is calculated using the formula: HV = 1.854 × F / d², where F is the applied force in kgf and d is the average diagonal length in mm.
Indenter Geometry
The Vickers indenter is a square-based diamond pyramid with an angle of 136° between opposite faces. This geometry ensures that the hardness value is independent of the applied load, making the test suitable for a wide range of materials from soft metals to hard ceramics.

Calculation Examples

  • HV = 1.854 × 10 kgf / (0.1465 mm)² = 864 HV
  • For a 5 kgf load with 0.200 mm diagonal: HV = 1.854 × 5 / (0.200)² = 232 HV

Step-by-Step Guide to Using the Vickers Hardness Calculator

  • Input Requirements
  • Calculation Process
  • Result Interpretation
Using the Vickers Hardness Number Calculator is straightforward and requires only basic test parameters. The calculator automates the complex mathematical calculations and provides accurate results with proper error handling.
Required Inputs
1. Test Load (kgf): The applied force during testing, typically ranging from 0.01 to 120 kgf depending on material hardness and test requirements. 2. Diagonal Measurements (mm): Both diagonals of the square indentation must be measured accurately using a calibrated microscope. 3. Material Type: Select the appropriate material category for proper result interpretation.
Calculation Steps
The calculator performs the following steps: 1. Validates input values against standard ranges, 2. Calculates the average diagonal length, 3. Applies the Vickers formula, 4. Provides the hardness number with appropriate units, 5. Calculates additional metrics like hardness range and statistical measures.

Practical Examples

  • Input: Load = 10 kgf, d1 = 0.145 mm, d2 = 0.148 mm → Output: HV = 864
  • Input: Load = 5 kgf, d1 = 0.185 mm, d2 = 0.187 mm → Output: HV = 265

Real-World Applications of Vickers Hardness Testing

  • Material Science Research
  • Quality Control
  • Engineering Applications
Vickers hardness testing finds extensive applications across various industries and research fields. Its versatility and accuracy make it an essential tool for material characterization and quality assurance.
Metallurgical Applications
In metallurgy, Vickers testing is used for: heat treatment verification, alloy development, weld quality assessment, and material selection for specific applications. The test provides critical data for understanding material behavior under different conditions.
Ceramic and Composite Materials
For ceramics and composites, Vickers testing helps determine: sintering quality, phase distribution, interface strength, and overall material integrity. The test is particularly valuable for brittle materials where other hardness tests may cause cracking.
Thin Films and Coatings
Vickers testing is essential for evaluating: coating adhesion, film thickness effects, surface modification results, and wear resistance properties. Low-load testing (microhardness) is particularly useful for thin film characterization.

Industry Standards

  • Steel heat treatment verification: HV 200-300 for annealed, HV 400-600 for hardened
  • Ceramic quality control: HV 800-1200 for alumina, HV 1500-2000 for silicon carbide

Common Misconceptions and Correct Methods

  • Measurement Errors
  • Interpretation Mistakes
  • Best Practices
Several misconceptions exist regarding Vickers hardness testing that can lead to inaccurate results. Understanding these common errors helps ensure reliable measurements and proper result interpretation.
Diagonal Measurement Errors
Common errors include: measuring only one diagonal, using uncalibrated equipment, improper lighting conditions, and operator bias. Always measure both diagonals and use calibrated equipment with proper illumination.
Load Selection Mistakes
Inappropriate load selection can cause: excessive deformation, cracking in brittle materials, or insufficient indentation size. Follow material-specific guidelines and consider the material's expected hardness range.
Surface Preparation Errors
Poor surface preparation leads to: inaccurate measurements, inconsistent results, and reduced test reliability. Ensure proper polishing, cleaning, and surface flatness before testing.

Common Errors and Corrections

  • Error: Using 100 kgf on soft aluminum → Correct: Use 5-10 kgf for accurate results
  • Error: Measuring only one diagonal → Correct: Always measure both diagonals and average

Mathematical Derivation and Examples

  • Formula Derivation
  • Unit Conversions
  • Statistical Analysis
The Vickers hardness formula is derived from the relationship between applied force, indentation area, and material resistance. Understanding the mathematical principles helps in proper result interpretation and troubleshooting.
Formula Derivation
The Vickers hardness number is calculated as: HV = F / A, where F is the applied force and A is the surface area of the indentation. For a square pyramid with 136° angle, the area is A = d² / 1.854, leading to HV = 1.854 × F / d².
Unit Considerations
The formula uses kgf for force and mm for diagonal length, resulting in HV units of kgf/mm². However, HV is typically reported as a dimensionless number, with the units implied. Conversion to other hardness scales (Rockwell, Brinell) requires empirical relationships.
Statistical Analysis
Multiple measurements should be taken to account for material heterogeneity and measurement variability. Standard statistical methods (mean, standard deviation, confidence intervals) should be applied for reliable hardness characterization.

Mathematical Examples

  • Derivation: A = d² / 1.854 → HV = F / (d² / 1.854) = 1.854 × F / d²
  • Conversion: HV 300 ≈ HRC 30, HV 600 ≈ HRC 55 (approximate relationships)