Charpy Impact Test

The Charpy V-notch test is the dominant screening method for steel toughness, including ductile-to-brittle transition in ferritic steels used for pressure vessels and pipelines. A standard notched bar rests on anvils while a pendulum striker impacts the face opposite the notch; the machine measures how much kinetic energy is absorbed in fracture.

Results for full-size 10×10 mm specimens with 2 mm V-notch are reported as KV2; sub-size variants are scaled per standards. Acceptance criteria in project specifications may add shear lip percentage and lateral expansion alongside energy.

Charpy is temperature-sensitive; a transition curve (energy vs temperature) locates the upper shelf, transition region, and lower shelf. Misalignment, blunt strikers, or loose anvils bias energy low or high.

Charpy is not a direct fracture mechanics parameter, but with appropriate correlation studies it can relate to CTOD or KIc for some material classes. It remains essential for batch release and validating welding or heat-treatment procedures.