Vickers Hardness Number
Calculate Vickers Hardness Number (HV) from force and indentation diagonal. Free hardness calculator with surface hardness in MPa/GPa and tensile strength for metals.
About This Calculator
The Vickers Hardness Number Calculator computes the Vickers hardness (HV) of a material from the applied test force and the mean diagonal length of the resulting indentation. Named after the Vickers company where it was developed in 1921, this test is one of the most widely used methods for measuring material hardness across metals, ceramics, and surface coatings.
The Vickers hardness test uses a diamond pyramid indenter with a 136° angle. A known force F is applied to the specimen surface for a dwell time of 10–15 seconds, creating a square pyramid indentation. The two diagonals of the indentation are measured under a microscope and averaged to obtain d. The formula HV = 2F sin(α/2) / (g d²) then gives the hardness number in kgf/mm², where g = 9.80665 m/s² is the standard acceleration due to gravity.
This calculator also derives the surface area hardness H in MPa and GPa (H = HV × g), and provides an estimated tensile strength using the relation σᵤ = H / c, where c is a material-dependent constant (approximately 3 for metallic crystalline materials). The indenter angle can be adjusted from the standard 136°, and the tensile constant c can be customized based on the material being tested.
The Vickers test is governed by the international standard BS EN ISO 6507-1: Metallic materials — Vickers hardness test, which defines the test conditions, indenter geometry, and calculation method. Unlike Brinell hardness testing, Vickers uses a single indenter for all hardness ranges, making it a continuous scale suitable for everything from soft aluminum to hardened tool steel.
Common applications include quality control in heat treatment, case-hardening depth evaluation, weld zone characterization, and materials research. The small indentation size (typically 0.02–2 mm diagonal) makes Vickers ideal for thin sections, finished components, and microstructural analysis.
Frequently Asked Questions
What is the Vickers hardness test?
The Vickers hardness test measures a material's resistance to plastic deformation by pressing a diamond pyramid indenter with a 136° angle into the surface under a specific load for 10-15 seconds. The resulting square pyramid indentation is measured across its diagonals, and the average diagonal length is used to calculate the Vickers Hardness Number (HV). It is defined by the international standard BS EN ISO 6507-1.
How is the Vickers hardness number calculated?
The Vickers hardness number (HV) is calculated using the formula HV = 2F sin(α/2) / (g d²), where F is the applied force in newtons (N), α is the indenter angle (136° for standard diamond pyramid), d is the mean diagonal length of the indentation in millimeters (mm), and g is the gravitational acceleration (9.80665 m/s²). The result is expressed in kgf/mm².
What is the surface area hardness (H) from Vickers test?
The surface area hardness H is derived from the Vickers hardness number by multiplying HV by gravitational acceleration: H = HV × 9.80665. This gives hardness in MPa. Further dividing by 1000 gives the value in GPa. This parameter represents the actual indentation pressure in SI units and is used in engineering material property analysis.
How do I estimate tensile strength from Vickers hardness?
Tensile strength σᵤ can be estimated from the Vickers hardness using the relation σᵤ = H / c, where H is the surface area hardness in MPa and c is a constant. For metallic crystalline materials, c is approximately 3 as a rule of thumb. This relationship provides a useful nondestructive estimate of strength, though actual values depend on material composition and processing.
What is the Vickers hardness number for common materials?
Typical Vickers hardness values vary by material: pure iron ranges from 30-80 HV5, carbon steel 55-120 HV5, aluminum alloys 15-60 HV, copper 40-105 HV, and hardened tool steels can reach 700-1000 HV. The exact value depends on composition, heat treatment, and processing. The number after HV (e.g., HV5) indicates the test load in kgf.
What is the difference between Vickers and Brinell hardness?
Vickers and Brinell are both indentation hardness tests, but they use different indenters. Vickers uses a diamond pyramid with a 136° angle and is suitable for all materials including thin sheets and case-hardened layers. Brinell uses a carbide ball indenter and is better for rough or coarse-grained materials like cast iron. Vickers provides a continuous scale from soft to very hard materials, while Brinell is limited by ball deformation at high hardness.
What force and diagonal values are typical for Vickers testing?
Standard Vickers test loads range from 0.01 kgf (microhardness) to 100 kgf (macrohardness), corresponding to forces from 0.098 N to 980.7 N. Common loads are 0.5, 1, 2, 3, 5, 10, 20, 30, 50, and 100 kgf. Indentation diagonals typically range from 0.02 mm for microhardness to 2 mm for macrohardness tests on soft materials.
Can Vickers hardness be used for quality control?
Yes, Vickers hardness testing is widely used in manufacturing quality control and materials research. It is ideal for evaluating heat treatment effectiveness, case hardening depth, weld zone hardness gradients, and material consistency. The small indentation size makes it suitable for finished components and thin sections where minimal surface damage is critical.