Job # 6
To perform impact test on different steel samples
Purpose:
To determine the modulus of toughness of steel in tension and in bending.
Apparatus:
- Charpy impact testing machine
- Steel samples, circular rod for tension test and specimen with square cross section for bending test
Related theory:
- Toughness: The ability of material to absorb energy in plastic range as load is increased from 0 to failure.
- Modulus of toughness: It is the amount of work done on a unit volume of material as a simple tensile force is increased from 0 to failure.
- Types of loads:
- Static load: Loads which do not change their magnitude, direction and position. e.g. self weight of anything.
- Dynamic load: The loads which change their magnitude, direction and position. e.g traffic load on roads, bridges.
- Impact load: The sudden application of the significant magnitude of load in a short interval of time. e.g. earth quack produces impact load.
Procedure:
- Measure the dimensions of a specimen. Also, measure the dimensions of the fork i.e its radius and mass.
- Raise the hammer and note down initial reading from the dial, which will be energy to be used to fracture the specimen.
- Place the specimen for test and see that it is placed center with respect to hammer. Check the position of notch.
- Release the hammer and note the final reading. Difference between the initial and final reading will give the actual energy required to fracture the Specimen.
- Repeat the test for specimens of other materials.
- Compute the energy of rupture of each specimen.
