At Metallurgical Testing Labs we have a new 300J impact machine which is capable of Charpy and Izod testing from temperatures of -196°C to 300°C. The temperatures and testing parameters are controlled by BS and ASTM Specifications to ensure repeatability. Calibrated temperature equipment is used during the heating up or cooling down processes to ensure that thorough heating is achieved prior to testing.
Top: 10×10 Charpy sample which displays characteristics of a ductile failure through plastic deformation, high Joule value and high lateral expansion.
Middle: 10×10 Charpy sample which displays characteristics of a brittle failure with low lateral expansion and a lower Charpy value.
Bottom: 10×10 Charpy sample in the “as machined” + HT condition.
Charpy testing machine showing the pendulum motion and the placement of the sample before testing commences.
Impact testing is based on Newton’s laws which states that energy cannot be created or destroyed only transferred from one place to another. Thus before the pendulum is released it contains potential energy. This potential energy transforms to kinetic energy once the pendulum is released. When the pendulum impacts the test specimen, the specimen absorbs some of the kinetic energy which slows the pendulum down which in turn renders a reading. This reading is based on how much energy the impact tester has transferred to the test specimen.