BS 131-1 is a British Standard covering the Izod impact test for metals using a pendulum impact machine and a notched test piece. It is used to evaluate the energy absorbed when a notched specimen is broken by a single blow, helping teams compare material toughness and notch sensitivity.
This standard is most often referenced when a specification calls up an “Izod impact” requirement for metallic materials and you need a clear, repeatable setup for specimen geometry, machine configuration, test temperature control, and result reporting. If you need help mapping a customer callout to the right fixture style and verification approach, talk with our team.
BS 131-1: Methods for notched bar tests — The Izod impact test on metals
BS 131-1 is a metals impact-testing document focused on the Izod configuration (vertically clamped specimen impacted by a swinging pendulum striker). It is commonly used in legacy procurement documents, defense/industrial purchasing specs, and long-established laboratory test plans.
This is a procedure-driven standard that points directly to apparatus capability (pendulum impact tester), a defined specimen/fixture arrangement, and consistent reporting of absorbed energy.
Quick Definition
BS 131-1 defines how to run an Izod impact test on metallic specimens and how to control key variables such as specimen form, notch orientation, machine setup, striking energy selection, test temperature, and presentation of results.
What This Standard Covers
BS 131-1 focuses on test conditions for Izod impact testing on metals, including the notched test piece arrangement, the basic requirements for the impact machine, and how results are recorded.
Covered at a practical level: Specimen form and dimensions, specimen preparation, pendulum impact machine requirements, striking energy selection, test requirements, testing temperature, and reporting of results.
Why This Standard Matters in Testing
Impact results can vary significantly with notch geometry, temperature, and the exact test setup. BS 131-1 helps labs reduce disagreement between suppliers, test houses, and receiving inspection by tying the outcome to a defined Izod configuration and repeatable preparation and test conditions.
For QA/QC and procurement teams, this matters when impact energy is used as a release criterion, a comparative benchmark between heats/batches, or a screening check after processing (for example, heat treatment or forming routes) that may affect toughness.
Common Materials, Product Types, or Applications Covered
BS 131-1 is intended for metallic materials tested as notched-bar specimens. It is commonly encountered in legacy material verification programs and in sectors that maintain long-standing internal test procedures.
Common uses: Incoming material checks, process-change comparisons, qualification support testing, and comparative studies where an Izod impact value is specified for a metal or alloy product form.
Common Test or Verification Workflow
A typical BS 131-1 workflow ties together specimen preparation, temperature conditioning, impact testing, and documentation.
Common workflow: Machine and striker selection (energy range) → preparation of notched specimens to the required form/dimensions → conditioning to the required test temperature (when specified) → Izod impact test with the specimen clamped vertically and struck by the pendulum → recording absorbed energy and reporting results in the required format.
Practical caution: For meaningful results, the edition cited in the customer or regulatory document should match the lab’s procedure, especially where specimen details, machine configuration, or reporting expectations can differ across legacy methods.
Equipment Commonly Used for This Standard
BS 131-1 points primarily to pendulum impact testing equipment configured for the Izod method, along with supporting metrology and temperature-control tools.
Common equipment: Pendulum impact tester (Izod-capable) with appropriate capacity range; Izod specimen clamp/anvil arrangement; striker(s) suitable for the required configuration; specimen notch preparation equipment (as required by the lab procedure); temperature conditioning equipment when sub-ambient or controlled temperatures are specified; basic dimensional inspection tools for specimen verification.
If you are selecting a pendulum impact system or need the right clamp/striker arrangement to match the way your customer cites BS 131-1, you can request pricing for an Izod-capable configuration sized to your energy range and throughput.
How to Read This Designation or Revision
Designation: “BS 131-1” indicates British Standard 131, Part 1.
Date suffix: When written as “BS 131-1:1961”, the “1961” is the publication year of the cited edition. Because impact testing is sensitive to setup and specimen details, purchasing documents and test reports should reference the exact cited edition (including any amendments or confirmations required by the customer’s quality system).
Related Standards, Methods, or Frameworks
BS 131 is a multi-part series focused on notched-bar impact testing. Depending on how a customer specification is written, the Izod method (Part 1) may be called out alongside other notched-bar impact documents for Charpy testing or machine verification.
Common related references: BS 131-6 (Charpy V-notch precision impact testing) and BS 131-7 (verification of impact test machines used for precision Charpy V-notch energy determination).
Talk to us about BS 131-1 equipment and setup
If you need an Izod impact testing setup aligned to how your contract cites BS 131-1 (capacity, striker/clamp configuration, temperature conditioning, or reporting needs), contact our team to review your application and match the right system configuration.