ASTM E23-18 pdf download.Standard Test Methods for Notched Bar Impact Testing of Metallic Materials.
3. Summary of Test Method
3.1 The essential features of an impact test are: a suitable specimen (specimens ofseveral different types are recognized), a set of anvils, and specimen supports on which the test specimen is placed to receive the blow of the moving mass, a moving mass that has sufficient energy to break the specimen placed in its path, and a device for measuring the energy absorbed by the broken specimen.
4. Significance and Use
4.1 These test methods of impact testing relate specifically to the behavior of metal when subjected to a single application of a force resulting in multi-axial stresses associated with a notch, coupled with high rates of loading and in some cases with high or low temperatures. For some materials and temperatures the results of impact tests on notched specimens, when correlated with service experience, have been found to predict the likelihood of brittle fracture accurately. Further information on significance appears in Appendix X1.
5. Precautions in Operation of Machine
5.1 Safety precautions should be taken to protect personnel from the swinging pendulum, flying broken specimens, and hazards associated with specimen warming and cooling media.
6. Apparatus
6.1 General Requirements:
6.1.1 The testing machine shall be a pendulum type of rigid construction.
6.1.2 The testing machine shall be designed and built to conform with the requirements given in Annex A1.
6.2 Inspection and Verification:
6.2.1 Inspection procedures to verify impact machines di- rectly are provided in A2.2 and A2.3. The items listed in A2.2 must be inspected annually 6.2.2 The procedures to verify Charpy machines indirectly, using verification specimens, are given in A2.4. Charpy impact machines must be verified directly and indirectly annually.
7. Test Specimens
7.1 Configuration and Orientation: 7.1.1 Specimens shall be taken from the material as speci- fied by the applicable specification.
7.1.2 The type ofspecimen chosen depends largely upon the characteristics of the material to be tested. A given specimen may not be equally satisfactory for soft nonferrous metals and hardened steels; therefore, many types of specimens are recognized. In general, sharper and deeper notches are required to distinguish differences in very ductile materials or when using low testing velocities.
7.1.3 The specimens shown in Figs. 1 and 2 are those most widely used and most generally satisfactory. They are particu- larly suitable for ferrous metals, excepting cast iron. 3 The Charpy specimen designations are V-notch and U-notch. N OTE 1—Keyhole notch specimen is similar to U-notch, except the notch width is 1.6 mm or less.
7.1.4 The specimens commonly found suitable for powder metallurgy materials are shown in Figs. 3 and 4. Powder metallurgy impact test specimens shall be produced following the procedure in Practices B925. The impact test results of these materials are affected by specimen orientation. Therefore, unless otherwise specified, the position of the specimen in the machine shall be such that the pendulum will strike a surface that is parallel to the compacting direction. For powder metallurgy materials the impact test results are reported as unnotched absorbed impact energy.
7.1.5 Sub-size and supplementary specimen recommenda- tions are given in Annex A3.
7.2 Specimen Machining:
7.2.1 When heat-treated materials are being evaluated, the specimen shall be finish machined, including notching, after the final heat treatment, unless it can be demonstrated that the impact properties ofspecimens machined before heat treatment are identical to those machined after heat treatment.
7.2.2 Notches shall be smoothly machined but polishing has proven generally unnecessary. However, since variations in notch dimensions will seriously affect the results of the tests, adhering to the tolerances given in Fig. 1 is necessary (Appen- dix X1.2 illustrates the effects from varying notch dimensions on V-notch specimens).ASTM E23 pdf download.