Semester 1 / Properties of Materials / Mechanical Properties / Charpy Impact Test

Charpy Impact Test

1 min read Last updated Sat Jun 27 2026 08:46:52 GMT+0000 (Coordinated Universal Time)
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Used to measure toughness by measuring energy absorbed during a high-strain-rate fracture.

Tester

Charpy Impact Tester

A pendulum hammer is released from height h1h_1 and swings through the specimen. It rises to height h2h_2 after fracture. Energy absorbed:

E=mg(h1−h2)E = mg(h_1 - h_2)

Higher EE means higher toughness.

Specimen

According to ASTM-E 23.

Charpy Impact Test Specimen

Specimen is notched to keep the crack straight.

Loaded state

Charpy Impact Test Specimen loaded state

Charpy vs Izod

  • Charpy
    Specimen supported at both ends. Hammer strikes the middle, opposite the notch.
  • Izod
    Specimen clamped vertically at 1 end (cantilever). Hammer strikes the free end.

Charpy is more common for metals. Results are not interchangeable.

Temperature Effect

Absorbed energy decreases as temperature drops for metals that undergo ductile-to-brittle transition. The transition temperature is determined by plotting absorbed energy vs temperature.

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