MEASURE MATERIAL TOUGHNESS
BY HAMMERING TILL IT FRACTURES
The Charpy impact value represents the ability of a material to absorb energy, usually determined under impact loading. It’s used in the Charpy impact test, a fracture toughness test method where a specimen supported at both ends is struck by a pendulum in the middle of its unnotched side.
For a Charpy impact specimen, the impact test of steel is the most widely used method for characterising steel’s ductile-to-brittle transition behaviour. The Charpy V-notch impact test (named for its V-shaped notch geometry) can be tested at different temperatures. The impact toughness at each test temperature may be determined by the energy absorbed during fracture, the shear percentage on the fracture surface, or the change in the width of the specimen (lateral expansion).
Why Charpy Testing?
The Charpy impact test is widely used because it is inexpensive and relatively simple. It is commonly used as a screening test in procurement and quality assurance for metallic products. As it’s popular, the Charpy impact test on mild steel is particularly common for structural and pressure equipment applications, where ductile behaviour at service temperature is critical to safety. Conversely, toughness decreases at lower temperatures; a material that is ductile at room temperature may become brittle at low service temperatures.
As an accredited impact test Singapore laboratory, Professional Testing Services provides the Charpy impact test services following multiple International standards for metallic materials. Our laboratory can conduct the test from room temperature to various sub-zero temperatures.
APPLICATION OF CHARPY IMPACT TEST
Being cost-effective and helpful in evaluating and assessing the quality of new products, the purpose of Charpy impact test for steel spans multiple industries:
Oil & Gas
Marine & Shipbuilding
Construction
Manufacturing
Aerospace
How Is Impact Strength Calculated?
The calculation for how to calculate impact strength from Charpy test is straightforward:
Impact Energy (Joules) = Initial Pendulum Energy − Remaining Energy After Fracture
In practice, this value is measured directly by the testing machine. The pendulum is released from a known height (corresponding to a known potential energy), strikes the specimen, and then continues to swing to a lower final height after fracture. The difference in height, converted to energy, represents the energy absorbed by the specimen during fracture.
Parameter | What It Tells You | Absorbed energy (J) | Primary toughness measure — higher = tougher |
|---|---|
Shear fracture (%) | Ductile vs brittle behaviour — higher shear = more ductile |
Lateral expansion (mm) | Plastic deformation at fracture — higher = more ductile |
Results are typically reported as the average of three or five specimens tested at the same temperature, with individual values documented for reference.
The Charpy vs Izod Impact Test
While both measure impact toughness, the difference between Izod impact test and Charpy impact test comes from setup and application differ:
Factor | Charpy Impact Test | Izod Impact Test | Specimen orientation | Horizontal (supported at both ends) | Vertical (cantilevered, one end fixed) |
|---|---|---|
Strike location | Opposite the notch | Same side as the notch |
Notch position | Faces away from pendulum | Faces toward pendulum |
Common standards | ASTM E23, ISO 148-1 | ASTM E23, ISO 180 |
Typical materials | Metals (steel, aluminium, alloys) | Metals and plastics |
Industry preference | Dominant for metals, especially steel | More common for plastics testing |
When deciding whether to go for a Charpy impact test for steel and other metal grades, Charpy remains the industry standard as it is specified in most structural steel, pressure vessel, and pipeline codes and specifications. Izod testing is primarily applicable to plastics and polymer-based materials.
Note:
At present, our laboratory offers Charpy impact testing only, conducted in accordance with applicable international standards and supported by controlled testing conditions to ensure accuracy and repeatability. Clients are encouraged to confirm test requirements and acceptance criteria at the enquiry stage to ensure full alignment with project and specification needs.
Test Standards
Our laboratory performs Charpy V-notch impact tests to internationally recognised standards:
ASTM A370
ASTM E23
AS 1544.2
BS EN ISO 148-1
MS ISO 148-1
Talk to us today
Professional Testing Service accredited labs are industry leaders in performing various fracture toughness test methods. Our lab specialists help you get the most out of your materials by providing in-depth, detailed impact test reports.
Contact us today to speak to an expert about our Charpy impact testing services or request a quote.
Frequently Asked Questions
1. What is the purpose of Charpy impact test for steel?
The purpose of Charpy impact test for steel is to measure the toughness of steel. Specifically, the amount of energy the material absorbs before fracturing under impact. This test helps determine whether steel will behave in a ductile (safe) or brittle (dangerous) manner at a specified temperature. It’s widely used for material qualification, low-temperature service assessment, welding procedure qualification, and compliance with industry codes and standards.
2. How much does a Charpy impact test cost?
The Charpy impact test cost depends on several factors, including the number of specimens, test temperature requirements, material type, and turnaround time. Testing a standard set of three specimens at one temperature is generally economical. Contact us with your requirements for a tailored quotation.
3. Can you test mild steel?
Yes. Charpy impact test on mild steel is one of our most common services. It is frequently performed for structural steel qualification, weld procedure testing, and incoming material verification.
4. What temperatures can you test at?
Our laboratory provides Charpy impact testing services in Singapore, from room temperature down to various sub-zero temperatures, depending on your specification and applicable standards.
