ISO 642:2024 specifies the Jominy end-quench method used to determine the hardenability of steel. It is commonly used to compare how different steels (or heat treatment conditions) respond to quenching by measuring hardness at set distances from a quenched end.
If you are unsure whether ISO 642 is the right fit for your alloy type, product form, or reporting format, you can talk with our team about your requirement before selecting equipment or a test plan.
ISO 642:2024 — Steel — Hardenability test by end quenching (Jominy test)
ISO 642:2024 is an International Standard that defines a standardized end-quench (Jominy) procedure for generating a hardenability profile from a single steel test piece. The output is typically a hardness-versus-distance curve taken along the length of the specimen after controlled heating and quenching.
Quick definition
What it is: A standardized Jominy end-quench hardenability test for steel.
What it produces: A hardness profile measured at defined distances from the quenched end (often presented as a Jominy curve).
What it is not: A full mechanical-property test method (it does not directly provide tensile strength, yield strength, or impact toughness).
What this standard covers
ISO 642:2024 defines a method to determine steel hardenability using an end-quench setup and a standardized cylindrical test piece. The standard identifies key aspects of the test piece and quenching arrangement (including the use of a 25 mm diameter specimen and a controlled end-quench water jet), and it defines how hardness is measured along prepared flats at specified distances from the quenched end.
| Covered by ISO 642:2024 | Typically handled by other documents or internal procedures |
|---|---|
| Standardized end-quench (Jominy) method for steel hardenability | Steel grade acceptance limits and pass/fail criteria (often set by a material or purchase specification) |
| Use of a defined specimen size (25 mm diameter, minimum length requirement) and prepared measurement flats | Heat treat recipe selection for production parts (process qualification and furnace uniformity validation) |
| Quenching arrangement parameters (end-quench water jet configuration and timing elements) | Correlation of Jominy results to specific part geometries or quench media (often handled by engineering models and experience) |
Why this standard matters in testing
Hardenability is a key factor in heat-treatment planning because it describes how deeply a steel can harden under a given quench severity. ISO 642 supports consistent comparisons between heats, suppliers, and process conditions by keeping the specimen geometry and end-quench method controlled.
For QA/QC teams, ISO 642 is often used to verify that a steel’s response to quenching aligns with expectations for intended section sizes, without needing to machine and quench multiple part geometries.
Common materials, product types, or applications covered
This standard applies to steel hardenability evaluation using the Jominy end-quench approach. It is commonly referenced in metallurgical labs supporting:
- Steel mills and service centers (material characterization and heat-to-heat comparison)
- Heat treaters (process troubleshooting and verification work)
- Automotive, industrial, and general manufacturing (gear, shaft, fastener, and tooling supply chains where quench response matters)
- R&D teams working on alloy development or heat-treatment optimization
Common test or verification workflow
ISO 642 testing is typically executed as a controlled sequence that produces a hardness profile along the specimen length.
Common workflow: Machine the standard cylindrical test piece; heat to the specified austenitizing condition; transfer to the end-quench fixture and quench one end with a defined water jet arrangement; prepare flats along the length to support hardness readings; measure hardness at specified distances from the quenched end; report results as hardness versus distance (a Jominy curve) or as an agreed codified result format.
In some defined applications, the standard allows the end-quench test to be replaced by an agreed mathematical model that calculates the Jominy curve.
Equipment commonly used for this standard
ISO 642 is equipment-oriented: a repeatable end-quench setup and hardness measurement capability are central to producing comparable results.
Common equipment: Heat-treatment furnace suitable for austenitizing; Jominy end-quench fixture with controlled water supply and jet geometry; timing/handling tools to control the lag between furnace removal and quench start; specimen preparation equipment to produce consistent hardness measurement flats; hardness tester(s) appropriate for the selected hardness scale; measurement tools/fixtures to locate hardness indent positions accurately along the specimen.
If you are comparing end-quench fixtures, water-circulation options, or hardness tester configurations for your lab throughput, you can request a detailed quote for a setup matched to your workflow.
How to read this designation or revision
Designation: “ISO 642:2024” identifies the ISO standard number (642) and the publication year (2024).
Revision sensitivity: Test setup and reporting details can change between editions. ISO 642:2024 is Edition 3 and cancels/replaces ISO 642:1999, so procurement documents and internal procedures should cite the exact year/edition required.
Related standards, methods, or frameworks
ISO 642 is frequently used alongside hardness testing practices and customer-specific steel specifications that define acceptance limits based on Jominy distance points or curve shape. In some markets, the Jominy method is also specified in ASTM documentation for hardenability testing.
Get help selecting an ISO 642 test setup
If you need help matching an end-quench fixture, water control approach, specimen prep, and hardness testing capacity to the edition you must run, contact our team with your material type, target hardness scale, and expected test volume.