Vickers Hardness Testing to ISO 6507 and ASTM E384: Standards Comparison

Introduction

Vickers hardness testing is governed by two primary international standards: ISO 6507 (published by ISO — International Organization for Standardization) and ASTM E384 (published by ASTM International). While both standards define the same fundamental Vickers test principle, they differ in specific requirements for specimen preparation, indentation measurement, calibration, and documentation — affecting how results are reported and whether they are directly comparable across laboratories.

Understanding both standards is essential for laboratories, manufacturers, and specifiers operating in global supply chains where European (ISO) and North American (ASTM) standards are simultaneously required.

Common Ground: The Vickers Test Principle

Both ISO 6507 and ASTM E384 define Vickers hardness measurement using the same fundamental principle: a square-based diamond pyramid indenter with 136° face angles is pressed into a polished specimen surface under a defined load for 10–15 seconds. The mean diagonal length of the residual indentation is measured optically, and hardness is calculated from:

HV = 1.8544 × F / d²

Both standards cover the same load ranges (micro: ≥ 1 gf to < 200 gf; low-load: 200 gf to < 1 kgf; macro: 1 kgf to 100+ kgf) and both define calibration requirements using certified reference hardness test blocks.

Key Differences: ISO 6507 vs. ASTM E384

Standard Structure

• ISO 6507 is divided into three parts: ISO 6507-1 (test method), ISO 6507-2 (verification of testing machines), ISO 6507-3 (calibration of reference blocks)
• ASTM E384 is a single consolidated standard covering test method, machine requirements, and calibration

Diagonal Measurement Resolution

• ISO 6507-1 requires measurement resolution of at least 0.001 mm (1 µm) for diagonals >0.040 mm; 0.0001 mm (0.1 µm) resolution for very small diagonals below 0.040 mm
• ASTM E384 requires 0.0005 mm (0.5 µm) measurement resolution

Specimen Preparation Requirements

Both standards require metallographically polished surfaces for microhardness testing. ISO 6507 specifies minimum surface roughness requirements (Ra ≤ 0.1 µm for most microhardness loads). ASTM E384 specifies that the surface must be prepared so that the indent diagonals can be clearly measured — a functionally equivalent but less numerically specified requirement.

Indentation Spacing Requirements

Both standards define minimum spacing between adjacent indentations (to avoid work-hardened zone interaction):

• ISO 6507: Minimum 2.5× indent diagonal between adjacent indents; 2.5× diagonal from any edge
• ASTM E384: Minimum 3× indent diagonal between adjacent indents; 2.5× from edges

The ASTM E384 requirement for inter-indent spacing (3×) is slightly more conservative than ISO 6507 (2.5×) — important for case depth profiling in limited cross-section area.

Hardness Scale Designation

Both standards use identical HV notation and load designation — HV 0.5, HV 1, HV 10, etc. — making the numerical hardness values from both standards directly comparable at the same load.

Reference Block Certification

ISO 6507-3 defines the calibration procedure and uncertainty requirements for reference hardness test blocks. ASTM E384 requires calibrated reference blocks per ASTM E92 and specifies acceptable deviation limits for instrument verification.

Practical Implications for Global Suppliers

Manufacturers supplying to both European and North American customers may need to certify materials to both ISO 6507 and ASTM E384. In most practical cases, the hardness numbers are identical — the standards produce equivalent HV values from the same test. However, documentation, calibration certificate format, and specific procedural details must address the applicable standard’s requirements for the shipment destination.

Industrial Applications

In the bearing industry, hardness verification per both ISO 6507 and ASTM E384 may be required for global OEM qualification. In aerospace, NADCAP heat treatment accreditation requires hardness measurement per AS 7102 (which references both ISO and ASTM methods). In the automotive industry, global Tier 1 suppliers may need to demonstrate compliance with both standards.

Why Choose Infinita Lab for ISO 6507 and ASTM E384 Vickers Testing?

Infinita Lab provides Vickers hardness testing compliant with both ISO 6507 and ASTM E384 through our nationwide accredited mechanical testing laboratory network — including micro and macro loads with automated measurement and complete calibration documentation.

Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you.

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