An impact test used to determine the notch toughness of materials. In its most common form, it has been given the designation Charpy V-notch. The specimens are 55 mm long and have a square cross section of 10 mm. A two millimeter notch is ground on one surface at half the length. The specimen is positioned with the ends of the notched surface straddling two supports and is struck opposite the notch by a wedge shaped hammer at the end of a pendulum. The energy
absorbed in breaking the specimen is calculated from data about the mass and length of the pendulum, the initial height of the hammer and the height of the hammer after the fracture. The test is performed at a number of temperatures, the results of which provide information about the overall toughness of the metal and the temperature at which it can be expected to fail in a brittle manner. A typical Charpy testing machine is shown in Figure C-4.
