Charpy VS Izod: understanding the differences in Impact Testing
In industrial applications, evaluating how a material responds to sudden mechanical stress is a key aspect of performance assessment. This is particularly important for sectors such as automotive, aerospace and medical devices, where resistance to impact is a critical property. This property is known as toughness.
To measure this, two standardized methods dominate the laboratory landscape: the charpy impact test and the izod impact test. While they both measure the energy required to fracture a specimen, their methodologies and applications differ.
At FILAB, we believe that choosing the right test is the first step in “deciphering the DNA” of your materials.
What is the charpy impact test?
The Charpy test is a widely used method to determine the ductility or brittleness of a material.
- Application: it is highly versatile and commonly used for metals, composites, and plastics. It effectively simulates conditions where a component is supported at multiple points and subjected to a central impact.
What is the izod impact test?
Charpy VS Izod: the key differences
While both tests utilize a pendulum to measure absorbed energy, the distinction lies in the geometry of the test:
Feature | Charpy impact test | Izod impact test |
Specimen Position | Horizontal (Simple Beam) | Vertical (Cantilever) |
Notch Orientation | Faces away from the striker | Faces towards the striker |
Strike Point | Center of the specimen | Upper tip of the specimen |
Common Standards | ISO 179, ASTM E23 | ISO 180, ASTM D256 |
Which test should you choose?
The choice often depends on your specific industry standards and the material’s intended use.
- Choose Charpy if you are testing metals or if your product specifications require ISO 179 compliance (common in European plastics markets).
- Choose Izod if you are characterizing polymers for markets where ASTM D256 or ISO 180 is the norm (often preferred in North American plastics industries).
Beyond the Test: FILAB’s Expertise
At FILAB, we go beyond simple mechanical testing. We combine impact tests with advanced characterization to provide a complete diagnosis:
Morphological Analysis (SEM): we observe the fracture surface to identify brittle or ductile failure modes
Thermal Analysis (DSC): we check if the crystallinity or curing process has impacted the mechanical properties
Chemical Analysis: we verify if the polymer composition or additives have affected the material’s toughness
Conclusion
Both Charpy and Izod tests are essential tools for ensuring the safety and reliability of your products. The “best” test is simply the one that aligns with your regulatory requirements and real-world application.