Charpy Impact

In the Charpy test, a notched specimen is placed horizontally on two supports and struck by a pendulum hammer from the face opposite the notch. The energy lost by the pendulum is the energy absorbed in fracturing the specimen, read in joules. The specimen is horizontal and supported at both ends — this is what distinguishes it from the Izod test.

The purpose is to assess the material's fracture behaviour and ductility under sudden loading. When repeated at different temperatures, the temperature range where the material transitions to brittle behaviour is determined; this is decisive information for steels intended for cold climates.

• Structural steels and pressure vessel steels
• Weld and heat-affected zone specimens
• Pipeline steels
• Castings and forgings
• Structural components operating at low temperature

• ISO 148-1 (metallic materials — Charpy pendulum impact test)
• ASTM E23 (notched bar impact testing of metallic materials)
• EN 10045 (superseded by ISO 148-1; still referenced in older specifications)
• ISO 179-1 (Charpy impact for plastics)

Specimen

Standard cross-section bar; V- or U-notched

Notch type

Stated in the specification; V-notch is common for metallic materials

Test temperature

From the specification; the specimen is conditioned if low temperature is required

Quantities measured

Absorbed energy (J), lateral expansion, percentage ductile fracture on the fracture surface

• Charpy pendulum impact machine with a calibrated hammer
• Specimen notching machine and notch-checking projector
• Low-temperature conditioning bath and thermometer
• Specimen transfer tongs (limiting temperature loss)
• Fracture surface examination setup

• The specimen must be machined to standard dimensions and the notch geometry checked.
• Sampling location and orientation (longitudinal/transverse) are chosen per the material standard.
• Sets of three specimens are usually tested.
• In the low-temperature test, the specimen must be broken within the defined time after transfer.
• For welded specimens, the notch location (weld, HAZ, base metal) must be stated.

A single break takes seconds. Total duration depends on specimen machining, notching and low-temperature conditioning; if a transition curve is required, sets are tested at many temperatures.

1. 1Specimens are machined to standard dimensions and notched.
2. 2Notch geometry is checked.
3. 3The specimen is conditioned if a test temperature is required.
4. 4The specimen is placed on the supports with the notch facing away from the striker.
5. 5The pendulum is released and the specimen is broken.
6. 6Absorbed energy is read; lateral expansion and the fracture surface are assessed.
7. 7The set average and individual values are reported.

The method standard defines how the test is performed, not what the result should be. The acceptance limit comes from the material standard, the product specification or the customer's technical drawing; this page therefore gives no numerical limit.

Assessment is usually based on the set average and a single-specimen lower limit; both are defined in the material standard. The ductile/brittle ratio on the fracture surface and lateral expansion are additional information supporting the energy value.

• Specimen identification, material type and cast/batch number, if any
• Specimen geometry, dimensions and preparation method
• Standard and test conditions applied
• Test temperature and ambient conditions
• Measured values and calculated quantities
• Fracture surface or indentation photographs (where applicable)
• Measurement uncertainty (if requested)
• A statement that the result applies only to the specimen submitted for testing

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

• EN 10204 (inspection documents for metallic products)
• EU 305/2011 Construction Products Regulation (for products used in construction)
• Harmonised standards applied according to the product family

The section below describes the field that the Charpy Impact test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

• Izod Impact
• High Cycle Fatigue
• Low Cycle Fatigue
• Crack Growth
• Tensile Test
• Compression Test
• Bending Test
• Bend Test
• Shear Test
• Torsion Test
• Peel Test
• Adhesion Test