---
term: "Charpy Impact Test"
category: "impact-testing"
shortDefinition: "A notched bar is broken by a swinging pendulum striker; absorbed energy KV or KU (joules) characterizes toughness and ductile-to-brittle transition versus temperature."
formula: "KV = E0 − E1"
relatedStandards: ["ISO 148-1","ASTM E23"]
url: "https://vectorbtc.com.tr/resources/glossary/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.