The charpy test and izod test.

1. Abstract (Objective of the experiment) – a paragraph
2. Impact tests determine impact toughness, a material property, most commonly by measuring thework required to fracture a test specimen under impact. Impact tests are useful in the analysisand prediction of the behaviors of different materials under impact stresses or dynamic loading.However, such tests cannot directly predict the reaction of a material to real life loading. Instead,the results are used for comparison purposes.

In Izod test, the specimen is placed in vertical position and the notch area is facing the pendulum.Meanwhile in Charpy test, the specimen is placed horizontally with un-notched area facing thependulum. Moreover, Izod impact specimen only has a V-notch specimen while Charpy impactspecimen has both U-notch and V-notch specimen. Charpy test result can indicate how brittle thematerials are. The most common method for the measurement of impact strength that is Charpytests is used in this experiment

4. Introduction – one page

In the Izod impact test, the test piece is a cantilever, clamped upright in an anvil, with a Vnotch at the level of the top of the clamp. The test piece is hit by a striker carried on a pendulum which is allowed to fall freely from a fixed height, to give a blow of 120 ft lb energy. After fracturing the test piece, the height to which the pendulum rises is recorded by a slave friction pointer mounted on the dial, from which the absorbed energy amount is read.

Charpy Impact Test: The principle of the test differs from that of the Izod test in that the test piece is tested as a beam supported at each end; a notch is cut across the middle of one face, and the striker hits the opposite face directly behind the notch. When the results of a number of tests performed in different temperatures are plotted, ductile-to-brittle transition curves, as in Fig. 3, may be obtained. As the temperature is reduced through the transition range, the fracture surface changes from one having a ‘fibrous’ or ‘silky’ appearance with much distortion at the sides, to one of completely crystalline appearance with negligible distortion. There is a strong correlation between the energy absorbed and the proportion of the cross-section which suffers deformation in fracture, and the fracture surface is frequently described in terms of the percentage of its area which is crystalline in appearance. Typical fracture appearances with crystallinity increases as the temperature is reduced.In the United States, the most common impact test is the Charpy impact test. The Charpy impacttest is a high strain rate test that measures the work required to rupture a specimen in flexure.Charpy specimens are uniform, rectangular prismatic specimens with one notch per specimen toencourage rupture

The Charpy testing machine is comprised essentially of a hammer with a striking head (a wedgeshaped head was used in this laboratory) attached to a nearly frictionless pendulum with a knownpotential energy. When released from a known height, the hammer strikes the Charpy specimenplaced in the anvil, usually fracturing it. The testing machine then records the amount of energyused to fracture the specimen by determining the difference in potential energy of the hammerbefore release and at the peak of its upswing after rupture

5. Procedure (List of equipment used for the experiment)

Obtain and measure each specimen

6. Learn how to position specimen in the anvil. Find out the proper position of the impact head and the height the pendulum should be set
7. Two people must set the pendulum in the raised position and one must stay supporting until the specimen has been secured.
8. Secure the specimen and confirm that it is center.
9. Set pointer on upper limit of the scale.
10. Release pendulum.
11. Record all results from scale reading on impact machine.
12. Use break system on machine to stop pendulum. NEVER ATTEMPT TO STOP MANUALLY.
13. Examine fracture surfaces.

Equipment

• Impact Machine
• 2 Brass Specimens
• 2 Aluminum Specimens
• 2 Steel Specimens

14. Discussion of Results (Include lab data, table, graph, etc..)-more than 1 page
15. Conclusions – a paragraph
16. References