DIN EN ISO 642 is a standardized method for determining the hardenability of steel using the end-quenching (Jominy) test. It is used to generate a hardness-versus-distance profile that helps compare steels and heat-treatment responses in a consistent, repeatable way.
This standard is commonly referenced by steel producers, heat treaters, and QA/QC labs when hardenability needs to be confirmed for material approval, process control, or troubleshooting. If you need help matching the cited edition to your lab setup and reporting needs, talk with our team.
DIN EN ISO 642: Steel — Hardenability test by end quenching (Jominy test)
DIN EN ISO 642 is the German adoption of the EN ISO edition that is based on ISO 642. It defines a recognized end-quench (Jominy) hardenability test workflow for steel, including how results are developed as a hardness profile along the test piece.
In most lab environments, this standard functions as a practical method reference: it ties together specimen preparation, end-quench execution, and post-quench hardness measurement so results can be compared across heats, suppliers, and production lots.
Quick Definition
DIN EN ISO 642 describes the Jominy end-quench test used to evaluate steel hardenability by quenching one end of a standardized test piece and measuring hardness at specified distances from the quenched end to form a hardenability (Jominy) curve.
What This Standard Covers
This standard covers a controlled end-quenching procedure for steel and the associated hardness measurements used to express hardenability as a curve (hardness versus distance from the quenched end).
What it focuses on: A repeatable way to compare the through-hardening response of steels under a defined quench severity and geometry.
What it does not replace: Part-specific heat-treatment specifications, component geometry effects, and service-performance testing (the Jominy curve is typically an input to design and process decisions, not a complete performance qualification by itself).
Why This Standard Matters in Testing
Hardenability is a key material property for steels that will be heat treated, because it influences the ability to achieve target hardness and microstructure at depth. DIN EN ISO 642 provides a consistent, widely recognized basis for comparing steels and monitoring changes in melt chemistry, grain size, or heat-treatment practice.
For buyers and QA teams, the value is practical: a documented Jominy curve supports material approval decisions, supplier comparison, and investigation of hardness nonconformities without requiring a full component-level trial for every change.
Common Materials, Product Types, or Applications Covered
DIN EN ISO 642 is used primarily for steels where hardenability is specified, compared, or tracked over time. Typical use cases include:
- Heat-treatable steels used for shafts, gears, fasteners, and other load-bearing mechanical components
- Steel grades where consistent depth of hardness is important after quench and temper
- Incoming material verification or periodic supplier quality checks based on hardenability curves
The exact steel families and acceptance criteria typically come from a purchase specification, drawing note, or material standard that references the Jominy method.
Common Test or Verification Workflow
Most labs use DIN EN ISO 642 within a workflow that links heat treatment and hardness testing into one controlled procedure.
Common workflow: Prepare the standardized Jominy test piece and austenitize per the required conditions, end-quench one end using the specified fixture and water jet conditions, prepare flats or surfaces for indentation, then measure hardness at defined distances from the quenched end and report the hardenability curve.
Practical caution: The end-quench fixture condition (alignment, nozzle condition, water temperature/flow stability) and the hardness method selected can materially affect curve shape. For comparable results, labs typically control equipment setup and use consistent hardness verification routines.
Equipment Commonly Used for This Standard
DIN EN ISO 642 is equipment-driven: repeatability depends on controlled heating, a stable end-quench apparatus, and checked hardness measurement capability.
Common equipment: End-quench (Jominy) test fixture with controlled water jet/nozzle arrangement, austenitizing furnace suitable for the required temperature uniformity, transfer tools to minimize delay from furnace to quench, specimen machining/prep tools, and a calibrated hardness tester (commonly Rockwell and/or Vickers depending on the referenced hardness approach and reporting practice).
Common lab accessories: Water temperature control/monitoring, flow/pressure monitoring where used by lab practice, hardness test blocks for verification, and measurement tools to locate/record distance from the quenched end consistently.
If you are specifying a new end-quench station or upgrading hardness testing capacity to support Jominy curves, you can request a detailed quote for a configuration matched to your sample volume and reporting requirements.
How to Read This Designation or Revision
DIN EN ISO 642 indicates a standard that is adopted in Germany (DIN), aligned with the European adoption (EN), and based on an International Organization for Standardization document (ISO).
When the standard is cited with a date (for example, “DIN EN ISO 642:2024-11”), the date identifies the specific edition. Equipment setup, hardness scale selection, and reporting details can be edition-sensitive, so purchase orders, drawings, or customer requirements should be checked for the exact cited version before testing begins.
Related Standards, Methods, or Frameworks
Jominy hardenability testing is commonly used alongside hardness measurement standards and heat-treatment specifications that define austenitizing conditions, acceptance bands for curves, or grade-specific hardenability requirements.
Because the controlling requirement is often a customer specification or a material grade standard, it is good practice to confirm which hardness method and reporting format are expected for the cited application.
Need help aligning equipment and reporting to DIN EN ISO 642?
If you are planning a Jominy testing capability (or updating an existing station), we can help translate the standard’s workflow into an equipment package that fits your throughput, hardness scale needs, and traceability expectations. For equipment selection and configuration support, contact our team.