QUALITY & CERTIFICATION ·
The marking on a fastener must correspond to the product's actual properties. A bolt marked A4-80 that does not meet the mechanical requirements of that property class does not conform to its declared designation, even if the marking itself appears correct.
This distinction is essential for industrial fastener buyers: recognizing a designation is not the same as verifying conformity.
According to ISO 3506-1, the A4-80 designation identifies a specific combination of stainless steel grade group and mechanical property class.
The number 80 is therefore not merely a commercial description: it represents a verifiable mechanical requirement.
A product cannot be considered A4-80 simply because it is made from a material belonging to the A4 stainless steel family. It must also meet the requirements of the declared mechanical property class.
A marking may be inconsistent with the product when the declared property class is not supported by the fastener's actual characteristics.
Consider an illustrative case: a bolt marked A4-80 undergoes a tensile test performed according to the applicable method. If the results demonstrate that the component does not meet the requirements of that property class, the product cannot be accepted as conforming to the A4-80 designation.
This remains true even if the material's chemical composition falls within the limits specified for A4.
Correct chemical composition does not, by itself, demonstrate that the required mechanical property class has been achieved.
Likewise, a clearly legible marking is not proof of mechanical performance.
To assess the conformity of a supply, three elements must be distinguished.
| Element | What it allows buyers to verify |
|---|---|
| Fastener marking | The declared material designation and mechanical property class, according to the applicable marking rules |
| Chemical analysis | Whether the material composition meets the specified requirements |
| Mechanical testing | The actual mechanical properties of the tested samples, according to the applicable test methods and criteria |
These checks are not interchangeable.
Engineers and buyers may select a threaded connection based on the mechanical properties associated with the specified property class.
If the supplied product does not meet those properties, one of the technical assumptions underlying the selection is no longer valid.
The consequences depend on the application, loads and joint design, but the principle remains unchanged: a fastener that does not conform to the declared property class cannot be treated as equivalent to the required class.
The issue is not merely price or perceived quality. It concerns the reliability of the technical specifications used to purchase and install a component.
An inspection document must be evaluated according to what it actually certifies, not merely by the title printed at the top.
For a supply requiring a specific mechanical property class, it is important to verify that:
Documentation of chemical composition must not be confused with verification of mechanical strength.
If results are inconsistent, conformity must be investigated before the product is accepted as meeting the required property class.
At the customer's request during the ordering stage, Anchor Pro performs tensile tests to fracture on fastener samples, determining tensile strength, proof strength and elongation.
For chemical composition, Anchor Pro uses documentation provided by its raw material suppliers. Mechanical and chemical data are assessed according to the supply specifications and applicable inspection requirements.
A marking must correspond to demonstrable properties, not merely declared ones.
For fastener supplies with specific material, mechanical property class and documentation requirements, contact Anchor Pro.
MATERIALS & PROPERTIES
A4-70 and A4-80 belong to the same stainless steel family but have different mechanical properties. Compare their strength requirements and selection considerations.
READ ARTICLE →
QUALITY & CERTIFICATION
An EN 10204 3.1 inspection certificate is an inspection document issued by the manufacturer that declares the compliance of the products with the requirements of the order and reports the results of specific inspection.
READ ARTICLE →