In welding quality control, it is essential to complement tensile tests (ISO 5178) with impact tests (Charpy method) to assess the fracture toughness of welded joints, especially in applications subjected to dynamic loads or extreme temperatures.
ISO 5178 regulates tensile testing of weld metal, while ISO 148-1 and ISO 148-2 define the methodology and requirements for proper execution of Charpy pendulum impact tests.
Why perform Charpy tests on welded joints
Charpy tests measure the energy absorbed by a notched specimen at the moment of fracture, offering a direct evaluation of the material’s resilience. These tests are particularly useful to:
- Determine the Ductile-to-Brittle Transition Temperature (DBTT)
- Verify the robustness of welds under accidental impacts or vibrations
- Qualify materials for critical sectors such as shipbuilding, offshore, cryogenic, and rail transport
Applicable standards
- ISO 148-1: Test method for Charpy impact testing on metallic materials
- ISO 148-2: Verification and calibration of Charpy pendulum machines
- ISO 5178: Longitudinal tensile testing of weld metal (not for impact)
Correct interpretation of the standards is crucial to ensure valid and certifiable results.
Charpy test equipment: Cermac solutions
To ensure compliance with international standards, the laboratory must be equipped with:
- Cermac Charpy pendulum, energy range from 150 to 750 J, certified according to ISO 148-2
- Thermal chambers or refrigerated baths, operating range −60 °C to +20 °C
- Precision broaching machines for notching (KV, KU, KCU) with high accuracy
- Certified metrological instruments, including digital thermometers and chronometers
- TestingXE-R software, with traceability and integration to LIMS/ERP systems
The Cermac Charpy pendulum: precision, reliability, and integration
Cermac’s pendulum impact tester is engineered for high performance and full traceability, offering:
- Automatic hammer release and motorized test cycle
- Intuitive touch-screen user interface
- Testing at controlled temperatures
- Integration with RFID systems and Industry 4.0-ready reporting
- Metrological certification using ENR/NIST reference specimens for traceable accuracy
Recommended upgrades for advanced labs
ENR/NIST certified reference specimens
Use certified impact specimens to periodically verify pendulum accuracy, ensuring energy readings remain within standardized tolerances.
FATT curve (Ductile-Brittle Transition Temperature)
For materials sensitive to ductile-to-brittle transitions, perform tests at multiple temperatures to map the FATT curve and better predict in-service behavior.
Complete Charpy test procedure
- Specimen preparation: 55×10×10 mm dimensions, notched (KV/U) and centered on the weld or heat-affected zone (HAZ)
- Conditioning: maintain specimen at the target test temperature for 10–30 minutes
- Testing: position the specimen on the anvils and release the pendulum
- Reading: automatically record the absorbed energy
- Fracture analysis: visual inspection or SEM-based advanced fractography
- Archiving: store digital, traceable test data for certification or analysis
Industrial applications
| Sector | Application examples |
|---|---|
| Infrastructure | Bridges, viaducts, earthquake-resistant structures |
| Energy | Nuclear reactors, pipelines, wind turbines |
| Marine & Offshore | Impact-resistant structural welding |
| Automotive & Rail | Welded safety-critical components |
Cermac: your trusted partner for materials testing
Cermac designs and manufactures complete equipment for Charpy impact testing, including:
- ISO 148-2-compliant pendulum impact testers
- Integrated notching machines and climatic chambers
- Standards consulting and technical training
- Calibration services and scheduled maintenance
- Retrofit and upgrade services for existing equipment
With Cermac, every test becomes a reliable and traceable result.
Conclusion
The Charpy test is an indispensable tool for validating the resilience of welded joints. Implementing best practices—such as using certified specimens, controlling environmental parameters, and performing FATT tests—enhances laboratory performance and testing accuracy.
With the Cermac Charpy pendulum, you can perform fully compliant, automated, and traceable impact tests in line with the highest industrial standards.
📞 Contact us today for a tailored quotation
✉️ info@cermacsrl.com | ☎️ +39 02 9098 1113
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