Introduction
The Charpy impact test is a high strain-rate test to find the impact toughness of a material. In the Charpy impact test, a standard notched specimen is struck by a controlled weight pendulum swung from a predefined height. The impact test is required to find out the amount of energy a specimen absorbs during fracture. As the notch prepared in the specimen is generally in the shape of the English letter “V”, the process is also popularly known as Charpy V-Notch Test.
Charpy V-notch test is widely used in industry to understand fracture problems of materials. The test is known as the Charpy test as the French Scientist, Georges Augustin Albert Charpy improved the original impact test introduced by the American Scientist, S B Russel.
What is the Charpy Impact Test used for?
The main purpose of the Charpy impact test is to evaluate the resistance of a material against impact or shock leading. This property of the material is known as toughness. The energy absorbed by the material while fracturing gives a measure of the material’s toughness. The Charpy test provides a tool to study ductile-brittle transition. The test output results can decide whether a material can be called a brittle or ductile material.
Charpy Impact Testing Procedure
Charpy impact testing is performed on a pendulum testing machine. In general, 3 specimens are prepared and the test is performed on all three test specimens to get an average output value. In the Charpy impact testing machine the following steps are followed:
- The pendulum of the calibrated Charpy machine is lifted to the starting position.
- The test specimen is now placed correctly on the machine anvil using the centering device.
- Next, the pendulum mass hammer is released which swings down and hit the specimen to break it.
- The energy absorbed (in Joules) is calculated and tabulated.
- Then the test is performed for specimen 2 and specimen 3 respectively and the average value of absorbed energy is calculated.
While a test is executed, the absorbed energy by the material specimen is calculated from the difference between the pendulum mass height over the specimen before and after impact and the mass of the pendulum hammer itself.
Standards for Charpy Impact Testing
There are various standards that provide rules for Charpy impact testing. The widely used standards for Charpy Impact testing are:
- ASTM E23
- ASTM A370
- ASTM E208
- ASTM D6110
- ISO 148
- MPIF Standard 40
- IS 1757
Charpy Impact Test Specimen
Based on ASTM A370/ISO 148, the standard Charpy impact test specimen size is 10 mm × 10 mm × 55 mm. The Charpy impact test is executed on both notched or unnotched specimens. However, the notched specimen is the most widely used Charpy test specimen.
Again, there are two types of notches; V-notch and U-notch.
- V-notch is a V-shaped notch, 2 mm deep, with a 45° angle and 0.25mm radius along the base, and the common for industrial Charpy tests.
- U-notch or keyhole notch is a 5 mm deep notch with a 1 mm radius at the base of the notch.
In some circumstances, sub-size Charpy test specimens can be prepared with thicknesses less than 10mm. Some of the sub-size Charpy test specimen sizes are
- 10 mm × 7.5 mm × 55 mm,
- 10 mm × 6.7 mm × 55 mm,
- 10 mm × 5 mm × 55 mm,
- 10 mm × 3.3 mm × 55 mm,
- 10 mm × 2.5 mm × 55 mm.
Parameters affecting Charpy Impact Energy
Various factors affect the Charpy impact energy of the material. They are as follows:
- Yield strength: With an increase in the yield strength of the material, the impact energy decreases.
- Ductility: With an increase in ductility, the impact energy increases.
- Notches: Proper standardized notch dimensions are important for getting accurate output results.
- Temperature and strain rate: The test is generally performed at 230C (+/-50C). Different temperatures affect the ductility of the material.
- Fracture mechanism
Charpy Impact Testing Machine
The Charpy impact testing equipment is known as a pendulum impact tester. The apparatus consists of a pendulum of known mass and length. Fig. 1 below provides an image of a typical Charpy impact test machine. Pendulum impact testers are highly versatile and can be used to test a wide range of materials, including metals, polymers, composites, and ceramics. They are also available in a variety of sizes and capacities, depending on the needs of the user. Some models can even perform low-temperature impact testing, which is essential for materials used in cold environments.
One of the key benefits of using a pendulum impact tester is its ease of use. The machine requires minimal setup time and can be operated by anyone with basic training. It also produces highly accurate and repeatable results, ensuring that the data collected is reliable and consistent. Another advantage of using a pendulum impact tester is its durability. These machines are built to withstand harsh testing environments and can last for years with minimal maintenance. This makes them a cost-effective solution for companies that need to perform impact testing on a regular basis.
Overall, a pendulum impact tester is an essential tool for any manufacturer or engineer who needs to test the impact strength of materials. With its accuracy, versatility, and durability, it is the ideal choice for anyone looking to ensure the safety and quality of their products. So, invest in a high-quality Charpy Impact Testing Machine today and stay ahead of the competition!
Izod Impact Test vs Charpy Impact Test
There are two types of Impact Tests used in industries; the Charpy Test and the Izod Test. While the Charpy test is widely used for metals, the Izod test is more popular for non-metals. The following table lists the major differences between the Izod test and the Charpy test:
| Charpy Impact test | Izod Impact test |
| The specimen notch in the Charpy impact test can be a V-notch or a U-notch. | Izod impact test uses only V-notch on the specimen |
| In the Charpy impact test, the specimen is held horizontally | On the other hand, in the Izod impact test, the specimen is held vertically. |
| The Charpy impact test is used for metallic materials. | Izod impact test can be used for plastics and metals both. |
| The striking point in the case of Charpy impact testing is in the middle of the specimen. | Whereas the striking point in the case of the Izod test is at the upper part of the sample. |
| The specimen size in the case of the Charpy test is 55*10*10 mm | The specimen size in the Izod test is 75*10*10 mm |
FAQ’s
When is charpy impact test required?
For example, in the automotive industry, the Charpy impact test is used to evaluate the toughness of materials used in the manufacture of vehicle components, such as engine blocks, drive shafts, and suspension components. Similarly, in the aerospace industry, the test is used to evaluate the toughness of materials used in the manufacture of aircraft structures, such as wings, fuselages, and landing gear.
The Charpy impact test is also required by various standards and regulations, such as ASTM E23, ASME Section VIII, and ISO 148. These standards and regulations specify the testing procedures and requirements for the Charpy impact test, and ensure that the test is performed consistently and accurately. In addition, the Charpy impact test is often used in research and development, to evaluate the properties of new materials and to optimize their performance.
Overall, the Charpy impact test is an essential tool in the field of materials testing, and is required in a variety of industries and applications. Whether you are a manufacturer, a researcher, or a regulator, the Charpy impact test is a valuable tool for evaluating the toughness and durability of materials, and ensuring that they meet the required standards and specifications.
What does Charpy impact test measure?
The Charpy impact test is performed by placing a sample of the material to be tested in a specially designed holder. The holder is then struck by a weighted pendulum, which swings down and strikes the sample with a specific amount of force. The amount of energy absorbed by the material is then measured, which provides an indication of its toughness or resistance to brittle fracture. The results of the Charpy impact test can be used to determine the quality of materials used in a wide range of applications, including construction, automotive, and aerospace industries.
It is particularly important in the manufacturing industry as it helps to ensure that materials are strong enough to withstand the rigors of their intended use. It is also used in research and development to evaluate new materials and to compare the performance of different materials. In conclusion, the Charpy impact test is a vital method of testing the toughness of materials. It is a test that measures the amount of energy required to break a material under impact loading using a pendulum impact tester.
This test is widely used in the manufacturing industry to ensure the quality of materials used in construction and other applications. It is necessary to have reliable and accurate test results to ensure the safety and efficiency of the materials being used.
What is izod impact test?
The Izod impact test is widely used in various industries, including construction, automotive, and aerospace, to evaluate the strength and durability of materials such as plastics, metals, and composites.
During the test, a specimen is clamped vertically, and a pendulum is released from a specific height. The pendulum swings down and strikes the specimen, causing it to fracture. The energy absorbed by the specimen is then calculated by measuring the difference in the height of the pendulum before and after impact. This energy value provides an indication of the material’s ability to withstand sudden shock or impact.
The Izod impact test is a critical part of material testing and is used to determine the suitability of materials for specific applications. It helps manufacturers to select the right materials for products that require high impact resistance, such as safety helmets, automotive components, and construction materials. By conducting this test, manufacturers can ensure that their products are safe and durable, and meet the required industry standards.
Video on Charpy impact test
Conclusion
In conclusion, Charpy impact testing is an essential tool in determining the toughness and resilience of materials in various industries. The test is performed using a pendulum impact tester, which is designed to measure the energy absorbed by a material when struck by a hammer. This test has proven to be highly reliable and accurate in determining the impact strength of a material.
The results of Charpy impact testing are critical in making informed decisions about the quality and safety of materials used in construction, aerospace, automotive, and other industries. By measuring a material’s ability to absorb energy without fracturing, engineers and manufacturers can determine which materials are suitable for specific applications.
Credits
- Feature Image Brand : Zwick Roell
- Video : MaterialsScience 2000
