Scope:

ASTM E23 method is used to determine the behavior of a notched metal when it is subjected to an impact load; a high-intensity blow is applied over an instant. In this test, the loading rate is high, and in some cases, temperatures are extreme. Because of the notch, the resulting stresses are multiaxial. The two test methods used in this test are the Charpy (simple-beam) test and the Izod (cantilever-beam) test.

Test Procedure:

For ASTM E23, the following crucial features of an impact test are required: 

A specimen, a set of anvils, a specimen fixture that fixes the specimen in place to receive the blow of the moving weight, and a device for measuring the energy lost by the moving weight due to impact.

Charpy Impact Test:

The machine has a pendulum-type hammer. The notched specimen is held securely at each end. The pendulum is pulled to a height and released. The hammer strikes opposite the notch and breaks the specimen into two. Because of the impact, the pendulum doesn’t swing as far. It has lost energy. That lost energy is the energy that was needed to break the specimen. The specimen must break into two. Results from instances in which the pendulum doesn’t have enough energy to toss the specimen into two are not reported as a standard result.

Izod Impact Test: 

A pivoting arm is raised to a specific height and then released. The arm swings down hitting the notched sample thereby breaking the specimen. The energy absorbed by the sample is calculated from the height the arm swings to after hitting the sample. The Izod test is similar to the Charpy impact test but uses a different arrangement of the specimen under test. In the Izod impact test, the sample is held in a cantilevered beam configuration as opposed to a three-point bending configuration.

Video 01: Charpy impact test