What is the Charpy impact test and what information does it provide about material toughness?

• A. Charpy test measures the energy absorbed during impact; indicates toughness and potential brittle behaviour at given temperature.
• B. Charpy test measures the color of a material after impact.
• C. Charpy test measures the surface roughness after impact.
• D. Charpy test measures the rate of cooling.

Answer: (A)

The Charpy impact test measures the energy a material can absorb before it fractures when struck by a sudden impact. A notched sample is hit with a swinging pendulum, and the absorbed energy is found from the difference between the pendulum’s initial energy and what remains after fracture, usually reported in joules. This energy reflects toughness—the ability to resist rapid crack propagation. It also shows how the material behaves at a specific temperature: higher absorbed energy means tougher, more ductile fracture; lower energy indicates brittle behaviour. Because toughness can change with temperature, the test helps predict how the material will perform in service and identifies the temperature range where it shifts from ductile to brittle. The other options don’t fit because the Charpy test does not measure color changes, surface roughness, or cooling rate.