ASTM D256 / ASTM D6110

Standard Test Method for Determining the Charpy Impact Resistance of Notched Specimens of Plastics

Summary Description

The ASTM D256 Izod impact and ASTM D6110 Charpy impact test standards specify the characterization of resistance of plastics to breakage by flexural shock. In either standard, the test is performed by striking a standard specimen with a single swing of a standardized pendulum hammer. The specimen is prepared with a milled notch, which induces a stress concentration promoting brittle fracture. The energy absorbed by the specimen is determined by the swing height attained by the pendulum hammer following its strike. The two tests differ in their respective arrangements for holding the specimen, the Izod impact test holding it on a single end with the notch on the facing side to impact and the Charpy impact test supporting it on two ends with the notch on the reverse side. Properties that reference ASTM D256 and ASTM D6110 are impact resistance and break type.

Additional Test Standards of Relevance

  • ISO 180
  • ISO 179

Characterization Measurements and Relevant Tests

DatapointLabs offers a pair of tests that respectively address the properties covered under the ASTM D256 and ASTM D6110 standards. These include the following characterization measurements, as specified in the respective test standards [bracketed links refer to relevant tests in the DatapointLabs Test Catalog]:

Izod Impact

  • Impact resistance, break type [M-425]

Charpy Impact

  • Impact resistance, break type [M-427]

Test Procedure and Equipment Used

In general, a Dynatup POE 2000 apparatus is used in conjunction with a notched bar of standard dimensions for both impact tests. At set velocity and energy, the pendulum is released to impact the specimen. The test is completed when the pendulum completes one swing. For Izod impact testing, the sample is clamped vertically, with the notch on the side of impact. For Charpy impact testing, the sample is placed horizontally, with the notch opposite the side of impact.

Sample Conditioning and Non-Ambient Testing

Sample conditioning, if required, is carried out following specimen preparation in accordance with ASTM D618. Typical conditioning selections are ‘dry as molded’ (low humidity storage at 23°C) and 40 hours at 23°C and 50% relative humidity. Non-ambient testing may be carried out at any temperature between -53°C and 200°C.

Test Specimen Specification and Description

Specimen specifications under ASTM D256 and ASTM D6110 are as follows:

  • For Izod impact testing, specimens are typically suitably notched ASTM D790 or ISO 178 flex bars; see Izod Specimens for further details

  • For Charpy impact testing, specimens are typically suitably notched ASTM D790 or ISO 178 flex bars; see Charpy Specimens for further details

Characterization Measurement Descriptions

Typical characterization measurements under ASTM D256 and ASTM D6110 include:

  • Impact Resistance: The force required to fully break a standard specimen under impact

  • Break Type: reported as full break, hinged break, partial break or no break

Listing of DatapointLabs Tests Referencing ASTM D256 and ASTM D6110

The list of tests in the DatapointLabs test catalog that reference ASTM D256 and ASTM D6110 are as follows:

Standard Description
M-425 Izod Pendulum Impact
M-427 Charpy Pendulum Impact
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