Information on the most widely used ASTM standards within the materials testing industry
Vickers Hardness
Vickers hardness (HV) quantifies a material’s resistance to permanent deformation from a diamond indentor. It is defined as the ratio of the applied test load to the surface area of the resulting indentation. The Vickers hardness value is expressed as "HV" followed by the load (e.g., HV10 for a 10 kgf load) and is independent of the material’s hardness—unlike Rockwell, it uses a single indentor design for all materials.
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What's Vickers hardness testing?
Vickers hardness (HV) quantifies a material’s resistance to permanent deformation from a diamond indentor. It is defined as the ratio of the applied test load to the surface area of the resulting indentation. The Vickers hardness value is expressed as "HV" followed by the load (e.g., HV10 for a 10 kgf load) and is independent of the material’s hardness—unlike Rockwell, it uses a single indentor design for all materials.
Advantages and Limitations
Advantages
Versatility: Single indentor works for soft to ultra-hard materials (HV1 to HV2000+).
Precision: Indentation geometry is consistent, and diagonal measurement enables accurate area calculation.
Convertibility: HV values can be converted to other hardness scales via standard tables.
Suitability for small samples: Low load options allow testing of micro-components or thin layers.
Limitations
Slower than Rockwell: Requires microscopic measurement of indentation diagonals, increasing test time.
Sensitivity to surface finish: Rough or contaminated surfaces can skew diagonal measurements.
Not ideal for large-scale production: Less efficient than Rockwell for high-volume quality control.
Applications of Vickers Hardness Test
The test’s flexibility (wide load range + single indentor) makes it ideal for diverse scenarios:
All material types: Works for soft metals (aluminum, copper), hard steels, alloys, ceramics, plastics, and thin surface layers (e.g., coatings, nitrided layers).
Precision testing: Suitable for small components, microstructures (e.g., grain hardness in metals), and research samples where detailed hardness mapping is needed.
Quality control: Used in aerospace, automotive, electronics, and tool manufacturing to verify heat treatment effects, material uniformity, and component durability.
Cross-comparison: HV values can be converted to Rockwell, Brinell, or Shore hardness, enabling consistency across different testing standards.
Thin materials/surface layers: Low load options (e.g., HV0.1, HV1) minimize indentation depth, making it safe for thin sheets, foils, or shallow surface treatments.
Standards for Vickers Hardness Test
ASTM Standards
ASTM E92: Standard Test Methods for Vickers Hardness and Knoop Hardness of Metallic Materials
The primary U.S. standard, covering:
Load ranges (1 gf to 100 kgf) for Vickers testing.
Equipment calibration (indentor geometry, load accuracy, microscope measurement precision).
Sample preparation (surface finish, flatness, thickness—minimum thickness 1.5× the indentation diagonal to avoid substrate effects).
Dwell time requirements and error correction for uneven indentations.
ISO Standards
ISO 6507: Metallic materials — Vickers hardness test
The international benchmark, divided into 4 parts:
ISO 6507-1: Principles, test methods, and definitions.
ISO 6507-2: Verification and calibration of test machines.
ISO 6507-3: Calibration of reference blocks.
ISO 6507-4: Tables for converting Vickers hardness to other hardness scales.
ISO 6507 is technically aligned with ASTM E92, with minor differences in load notation and dwell time defaults.
Micro-Vickers and Nano-Vickers Standards
For ultra-low load testing (micro/nano scales):
ASTM E384: Covers microindentation hardness (including Vickers) for small volumes or thin layers.
ISO 14577: Metallic materials — Instrumented indentation test (includes nano-Vickers testing for ultra-thin films or microstructures).
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