Table of Contents
Definition
Charpy impact test is used to calculate the resistance capacity of metal specimen such as steel. It is a high strain rate test in which a standard notched specimen is hit with a controlled weight pendulum swinging from a specified height. Impact testing helps measure the amount of energy absorbed by a sample during fracture.
This test also called Charpy V Notch Test.
In the below figure, I have shown Charpy impact test machine.
The Charpy test indicates whether a metal is brittle or ductile. This is especially useful for ferritic steels, which exhibit a ductile-to-brittle transition with decreasing temperature.
Why Charpy Test is Performed?
The main purpose of this experiment is to find out if the material is brittle or ductile.
Materials that fracture without plastic deformation. The failure of a material with a large plastic deformation.
It is a method of measuring the toughness of a material and the amount of energy it absorbs when it breaks.
Charpy Impact Test Machine Description
The device consists of a pendulum of known mass and length, dropped from a known height to strike a knurled sample of material. The energy transferred to the material can be estimated from the difference in hammer height before and after failure.
The notch on the test piece affects the result of the impact test, so the size and shape of the notch should be consistent. The sample size can also affect the results, as the size determines whether the material exhibits planar deformation. This difference has a significant impact on our conclusions.
Charpy Impact Test Method
- Raise the pendulum to the starting position. Next, check if the tester is set up correctly.
- First, sharpy needs to calibrate his machine. To do this, turn the dial gauge to the en value and release the pendulum without placing the test object. The needle is at the starting value 0. The Charpy machine is now ready for testing.
- Then use the centering device to place the specimen in the correct position on the machine. i.e. then turn the dial gauge pointer down at the final value and release the pendulum.
- The pendulum is swung down and the sample is cut.
- The pendulum does not reach full height on the other side due to energy absorption by the sample.
- A dial indicator can be used to measure the amount of energy absorbed by the sample. Record the value of the dial indicator.
This test is performed to calculate whether the material is brittle or ductile. Brittle materials absorb less energy and ductile materials absorb more energy.