EN 10328 is a European test method for determining the conventional (effective) depth of hardening in iron and steel parts after surface heating processes such as surface hardening followed by quenching.
Because purchasing specs often cite a specific edition (and this document is listed as withdrawn by some national bodies), it is important to match the test setup and hardness criterion to the exact version referenced on the drawing or contract. If you need help aligning a lab procedure to the cited edition, talk with our team.
Iron and steel — Determination of the conventional depth of hardening after surface heating (EN 10328)
This standard is used when a component has been surface-hardened and you need a repeatable way to quantify how deep the hardened layer extends below the surface using hardness measurements on a prepared cross-section.
It is commonly referenced for process verification, supplier acceptance, and comparative checks when changing surface-hardening parameters (for example, power, time, quench conditions, or material condition).
Quick definition
What EN 10328 provides: A hardness-traverse approach to determine the depth from the surface to the point where hardness drops to a defined “hardness limit,” reported as the effective depth of hardening after surface heating.
What it does not provide: A complete surface-hardening process specification. It is a measurement method used after hardening, not a recipe for how to harden the part.
What this standard covers
EN 10328 defines a test method based on Vickers hardness testing on a cross-section normal to the hardened surface.
The depth is determined from a plotted hardness profile versus distance from the surface, using a defined hardness limit tied to the measured surface hardness (unless another criterion is agreed by the parties).
Why this standard matters in testing
Surface hardening is often used to increase wear resistance while retaining a tougher core. EN 10328 gives a consistent, auditable way to quantify the hardened layer depth so production lots, suppliers, and heat-treatment routes can be compared using the same measurement logic.
For QA/QC, the practical value is repeatability: consistent specimen preparation, consistent hardness indentation placement, and a consistent rule for converting the hardness profile into a single “depth of hardening” result.
Common materials, product types, or applications covered
This method applies to iron and steel components that have been surface-hardened by surface heating followed by quenching, where a hardened layer is present near the surface.
Typical use cases: Heat-treated machine elements, shafts, gears, and wear surfaces where drawings specify a minimum hardened depth or where process control requires tracking hardened layer depth over time.
Common test or verification workflow
A typical EN 10328 workflow is a hardness traverse on a prepared cross-section of the hardened part.
- Section the part at the specified location (or agreed region) to expose a cross-section normal to the treated surface.
- Prepare/polish the section so hardness impressions can be measured accurately without edge rounding or heat damage from preparation.
- Make Vickers indentations along one or more lines normal to the surface within a defined narrow band, using closely spaced depths near the surface and around the expected transition zone.
- Plot hardness (HV) versus distance from the surface and determine the depth where the hardness equals the defined hardness limit.
- Report the resulting effective depth of hardening for the specified area(s), along with any parameters that could influence results (sample description, heat treatment, test locations, and curves).
Equipment commonly used for this standard
Equipment selection is primarily driven by hardness method capability, sample preparation needs, and the ability to place/measure indentations accurately close to the surface.
Common equipment: Vickers hardness tester (micro/macro range as required by the specified load), metallographic sectioning and mounting tools, grinding/polishing system, and a measurement/analysis approach for building the hardness profile and determining the depth at the hardness limit.
If you are configuring a hardness testing setup (tester capacity, indentation measurement, and sample-prep workflow) for depth-of-hardening work, you can request a detailed quote for an equipment package matched to your part size and reporting needs.
How to read this designation or revision
Designation: “EN 10328” identifies the European standard for determining conventional depth of hardening after surface heating for iron and steel.
Edition sensitivity: Contracts may cite the year (for example, EN 10328:2005). Because national catalogs may list EN 10328 as withdrawn and replacements may be used in practice, the exact cited edition and acceptance criterion (hardness limit definition and test load) should be confirmed before testing begins.
Related standards, methods, or frameworks
EN 10328 is built around Vickers hardness testing practices and references the Vickers hardness test method standard for how HV measurements are made.
In some procurement contexts, later ISO-based documents for thickness/depth of surface-hardened layers may be used instead of EN 10328; ensure the drawing, customer specification, or governing contract defines which document controls.
Get help matching EN 10328 to your lab setup
If you need to align sample preparation, hardness tester loading range, and reporting outputs to a customer drawing that cites EN 10328, contact our team with the part details and the exact designation shown on the requirement.