Components with good toughness behaviour in the tensile test become brittle at low temperatures and lead to premature material failure. The Charpy impact test (Charpy V-notch test) is used to measure the toughness of materials under impact load at different temperatures! Test setup and test procedure For this reason, the so-called Charpy impact test or Charpy V-notch test is used to test the toughness of a material under an impact-like load as a function of temperature. In the Charpy impact test, a notched specimen is abruptly subjected to bending stress. The specimen is usually 55 mm long and has a square cross-section with an edge length of 10 mm. The notch in the middle has a V-shaped geometry (in special cases also U-shaped). The notch provides a defined predetermined breaking point, which generates a triaxial stress state in the notch base. The notched specimen is placed into the support of a pendulum impact testing machine. Figure: Test setup for Charpy impact testĪ deflected pendulum hammer is then released from a certain height. At the lowest point of the circular trajectory, the striker of the hammer hits the opposite notch-facing side of the specimen (impact velocity usually between 5.0 and 5.5 m/s). The sample is fractured by the striker and absorbs part of the kinetic energy of the hammer. With the remaining residual energy, the hammer swings out to a certain height. Due to the absorbed kinetic energy through the sample, however, it does not reach its initial height again. The deformation energy and thus the final height achieved depends on the toughness of the specimen. The tougher the material, the more it has to be deformed until it breaks.
The required deformation energies are correspondingly high and the pendulum energy is strongly absorbed. The hammer then only reaches a low final height after fracturing the specimen. Animation: Charpy impact test (V-notch test) Very brittle specimens, on the other hand, break almost without deformation and therefore require only a low deformation energy. The pendulum hammer swings almost at the initial level.
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