# Difference Between Izod and Charpy Methods (With Table)

Impact testing of materials for toughness and sensitivity is an important process in various fields. There are various standardized methods to perform this task and identify toughness. Two such processes are the Izod Method and the Charpy Method.

Both of these methods are used widely for determining the strength, toughness and sensitivity of the material. In both methods, a hammer is made to strike on the material under test and the difference in height before and after hitting is measured and the strength or toughness is calculated.

In the Izod and Charpy methods, a pendulum of known mass and length is adjusted to drop from a particular height.

## Izod vs Charpy Methods

The main difference between Izod and Charpy Methods is that in the Izod method, the sample notch is always facing the pendulum vertically and the striking point is on the upper tip of the given sample. In the Charpy method, the notch is kept facing away from the pendulum horizontally and the striking point is in the middle of the sample.

## What is the Izod Method?

The Izod method is an impact testing method given by Gilbert Izod in 1903. The method is used to test the impact of strain which is important in determining the life time of the material.

In the Izod method, the notch is kept vertical and facing towards the striker. The striking point in the Izod method is on the upper tip of the material. It has only a V notch. The Izod method can be used to test metals as well as plastics.

## What is the Charpy Method?

In 1901, Georges Charpy devised an improved and standardized method for impact testing using spring-loaded machines which came to known as the Charpy Impact testing method.

In this method, the equipment is adjusted in such a way that the hammer strikes the material under test, the material is further used to determine the notch sensitivity and the energy absorbed by the material is used to calculate the strength and toughness of the material.

The notch in the Charpy method is kept horizontal and facing away from the pendulum. The striking point of it is in the middle of the sample. The Charpy method has U notch and V notch.

## Main Differences Between Izod and Charpy Method

1. The Izod and Charpy methods are the impact testing methods, in both methods, a hammer is made to strike on the material from a particular height, the energy absorbed by the material is used to calculate the toughness of the material and the material is used to determine sensitivity.
2. In the Izod method, the notch is kept facing towards the pendulum vertically whereas, in the Charpy method, the notch is kept facing away from the pendulum horizontally.
3. In the Izod method, the material under test is placed vertically whereas in the Charpy method, the material under test is placed horizontally.
4. In the Izod method, the striking point is on the upper tip of the material, on the other hand, in the Charpy method, the striking point is in the middle of the material.
5. The Izod method has only a single notch which is named as V notch whereas in the Charpy method, there are two notches named as U notch and V notch.
6. In the Izod method, the hammer used for striking is a farming hammer whereas in the Charpy method, the hammer used is a ball pin hammer.
7. The Izod method is used for testing both metals and plastics whereas the Charpy method is used for testing metals.
8. The common dimensions of the equipment of the Izod method are 64*12.7*3.2 mm for plastics and 127*11.43 mm round bar for metals whereas the dimension of equipment in the Charpy method is 55*10*10 mm.
9. Some of the common specifications used in the Izod method are ASTM D256, ASTM E23 and ISO 180 whereas the common specifications in the Charpy method are ASTM E23, EN 10045-1, etc.

## Conclusion

In the Izod and Charpy method, the adjustment of the equipment is different but both the processes are used for the same purpose. In these methods, the energy is absorbed by the sample and this energy is used to calculate the toughness of the material and the sample is used to find the sensitivity of the notch sample. These methods play an important role in understanding the fracture problems of various materials such as metals and plastics.