Charpy Impact Test
The Charpy Impact Test is designed to measure how much energy a material can absorb when it is hit suddenly.
It helps determine if a material is tough (able to absorb energy without breaking) or brittle (likely to break under sudden forces).
How to use this metric
Higher is better in applications where a material is expected to absorb energy without fracturing. For example, in vehicles or building structures exposed to sudden impacts. Or in environments that are very cold or where materials are subject to sudden shocks, knowing a material's impact energy can help you avoid using brittle materials that might break unexpectedly.
The test's results guide decisions on material selection depending on whether the priority is resistance to fractures (high energy absorption) or other properties that might favor energy conservation (where lower impact values might still be acceptable).
Test Method:
Sample Preparation
A small bar of the material is cut, and a notch (a deliberate groove) is made on one side. This notch creates a point of weakness to focus the impact force during testing.
Setup and instrumentation
The notched specimen is placed in a pendulum impact testing machine, which securely holds the sample. The pendulum is calibrated to swing from a predetermined height, ensuring a consistent amount of energy for each test.
Conducting the test
The pendulum is released, swinging down to strike the notched specimen. As the pendulum hits the notch, it transfers its energy to the sample, causing it to break or crack.
Measurement The energy absorbed by the material is calculated from the difference in the pendulum's energy before and after the impact. This absorbed energy value is used to assess the material's overall toughness.