Impact test - Charpy V
The impact test is a standardized method to predict the steels sensitivety for a brittle fracture. First the pendulum drops without a test piece from its rest position and swings up to a certain height. This measures the loss of energy caused by friction in the construction. After that the test piece is placed into the path of the pendulum and is broken. The upsurge height will be less because the test rod absorbs energy until it breaks. From most machines you can read the fracture energy in kilopondmeter. Now it is possible determine the impact strength as the fracture energy of the cross section of the rod. The notch value is defined as the breaking energy per unit cross-section of the test bar at the height of the notch. In European standards, 4 temperatures have been established for these tests being carried out: + 20 °, 0 ° C, -20 ° or -40 °.