Metal Charpy (U-notched) Impact Test Method
The Charpy impact test, also known as the Charpy V-notch test, is a type of fracture testing methodology. It is used to determine impact fracture strength of particular metals. The Charpy U-notch test method, as specified in GB229–84, is intended to provide information regarding the transition of plasticity to ductile behavior in a material. This test method is appropriate for determining the impact toughness of metals that have been through a heat treatment process.
The purpose of this method is to measure the amount of energy a specimen absorbs prior to fracturing. The energy is a measure of the materials resistance to impact loading. The Charpy U-notch test is performed by mounting the specimen in a set-up and striking it with a pendulum. The pendulum has a striker, which is usually a weighted-arm, that impacts a notch on the specimen at high speed. The amount of energy absorbed by the specimen is determined by measuring the height that the pendulums striker drops and the oscillations of the pendulum after the collision.
The Charpy U-notch test is conducted on various pieces of material that have been machined according to the requirements of this test method. The version of the specimen that uses a U-notch is the most common type of Charpy impact testing. The U-notch is an angled notch, where the top end is on one side of the specimen and the bottom is on the other. This type of notch helps to focus stress on the notch inside the material, thus helping to direct the fracture path and also ensures that the fracture occurs in a certain direction.
The test involves the use of a suitable machine such as a Charpy or Izod impact tester. The machine must be equipped with a pendulum, a striker, and other components, including a specimen fixture and cutting fixtures. As part of the test set up, the specimen must be machined to a specific size and shape and a notch machined in one corner. The specimen is then placed in a specimen fixture connected to the pendulum arm, so that when the pendulum is struck, it will strike the corner of the specimen with the notch. As the pendulum swings, the specimen absorbs energy until it fails.
The energy absorbed by the specimen is determined by measuring the height that the pendulum’s striker drops, and the oscillations of the pendulum after the collision. The amount of energy absorbed is listed as the Charpy Impact Value.
This test method is used to measure certain mechanical properties of a material and help determine its suitability for specific applications. The Charpy U-notch test provides information regarding the impact strength of the material and helps engineers develop and design materials for better performance. This test method is not intended to be a measure of the material’s resistance to drop blows, sudden impacts, or other extreme environmental conditions. The Charpy U-notch test is a useful tool for measuring a material’s response to certain types of impacts and helps engineers develop products that are safe and reliable.
