Engineering Homework Help

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Objective
To become familiar with the Charpy impact test and to determine the effect of temperature on the impact
behavior of different metals. The qualitative results of the impact test can be used to determine
the ductility of a material.
Experimental Procedure

1. Prepare liquid baths at different temperatures and soak the specimens in the bath for 10 minutes before
testing. The temperatures can be measured using a thermocouple.

2. Lift the pendulum hammer until it latches and secure the lock to prevent accidental release of the
hammer

.
3. Once the hammer is raised, insert the specimen into the machine using tongs making sure it is centered
in the fixture with the notch facing away from the side to be impacted by the hammer.

4. The specimen must be tested within five seconds after removal from the bath.

5. To begin the test, remove the lock and release the pendulum by pressing on the lever.

6. After the specimen has been broken, the dial gauge will read the energy absorbed by the specimen.
Record this value.

7. Once the absorbed energy is recorded, you may use the mechanical brake to stop the pendulum from
swinging. Since using the brake changes the gage reading, be sure to record the data before using it.

8. Once the pendulum has stopped, retrieve the specimen and determine the percent of area of the
fractured face that has fibrous texture.

9. Repeat the test for all specimens at each temperature.

Virtual Lab Link
https://content.steeluniversity.org/simulators/cha…

You can use the above link to perform a simulated Charpy impact test.
Virtual Lab Test Requirement
Record the impact energy as the test temperature changes from -120o
C to 80o
C (20 trials). Plot the
relationship between impact energy and test temperature.

Exercises

1.Download the detailed test data from Blackboard, for each material, calculate the average and standard
deviation of the impact energy at each temperature. Tabulate the results in a table. Then, plot the impact
energy – temperature relationship for each material. Determine the DBTT for materials showing a sharp
transition temperature. Based on the graph, discuss the material behavior under temperature variations
and whether the graph line meets your expectation. Explain the reason.

2.The weight of the pendulum hammer is 45 lbs., and the length of the pendulum arm is 32 in. If the arm
is horizontal before striking the specimen, determine the potential energy of the tester and the striking
velocity