To determine impact strength of steel bars.

OBJECT: TO DETERMINE THE IMPACT STRENGTH OF THE STEEL BAR.

APPARATUS:

• Steel Bars
• Charpy Apparatus
• Izod Apparatus

THEORY:

1. TOUGHNESS TEST
   
2. CHARPY IMPACT STRENGTH TEST
   

CHARPY IMPACT STRENGTH APPARATUS

1. IZOD IMPACT STRENGTH TEST
   

IZOD IMPACT STRENGTH APPARATUS

METHODOLOGY:

OBSERVATIONS & DISCUSSIONS

• Method adopted for impact strength test of metal bar = ____________
  
• Dimension of bar = ____________________ in mm.
  
• Impact strength of bar = _________________KJ/m²
  

RESULTS:

or

IZOD IMPACT TEST

AIM: To determine the Impact strength (Specific impact factor) through the Izod test.

APPARATUS: Impact testing machine, MS Specimen

DIAGRAM:

PROCEDURE:

1. For conducting charpy test, a proper striker is to be fitted firmly to the bottom of the hammer with the help of the clamming piece.
2. The latching take for charpy test is to be firmly fitted to the bearing housing at the side of the columns.
3. The frictional loss of the machine can be determined by free fall test, raise the hammer by hands and latch in release the hammer by operating lever the pointer will then indicate the energy loss due to friction. From this reading confirm that the friction loss not exceeding 0.5% of the initial potential energy. Otherwise frictional loss has to be added to the final reading.
4. The specimen for izod test is firmly fitted in the specimen support with the help of clamping screw and élan key. Care should be taken that the notch on the specimen should face to pendulum striker.
5. After ascertaining that there is no person in the range of swinging pendulum, release them pendulum to smash the specimen.
6. Carefully operate the pendulum brake when returning after one swing to stop the oscillations.
7. Read-off position of reading pointer on dial and note indicated value.
8. Remove the broken specimen by loosening the clamping screw.

The notch impact strength depends largely on the shape of the specimen and the notch. the values determined with other specimens therefore may not be compared with each other.

TABLE:

PRECAUTIONS:

1. Measure the dimensions of the specimen carefully.
2. Locate the specimen in such a way that the hammer. Strikes it at the middle.
3. Note down readings carefully.

RESULT:

The Impact strength of the given specimen is ^𝐽

𝑚2

VIVA QUESTIONS:

1. In what way the values of impact energy will be influenced if the impact tests are conducted on two specimens, one having smooth surface and the other having scratches on the surface
2. What is the effect of temp? On the values of rupture energy and notch impact strength?
3. What is resilience? How is it different from proof resilience and toughness?
4. What is the necessity of making a notch in impact test specimen?
5. If the sharpness of V-notch is more in one specimen than the other, what will be its effect on the test result ?

APPLICATIONS:

1. in forging industry.

1. in the rubber industry.

CHARPY IMPACT TEST ON METAL SPECIMEN

AIM: To perform the Charpy impact test on materials.

APPARATUS:

Izod Impact test machine, test specimen, Vernier calipers, and steel rule.

IMPACT STRENGTH: The resistance of a material to fracture under sudden load Application.

MATERIALS: Mild steel (Square test pieces)

THEORY:

An impact test signifies toughness of material that is ability of material to absorb energy during plastic deformation. The type of test specimen used for this test is a Square Cross-section. The specimen may have single, two or three notches.

The testing machine should have the following specifications.

• The angle 0 between top face of grips and face holding the specimen vertical=90⁰ The angle of tip of hammer =75⁰±1⁰
  
• The angle between normal to the specimen and underside face of the hammer at striking point= 10⁰±1⁰
  
• Speed of hammer at impact=3.99 m/sec
  
• Striking energy=168N-m or Joules
  
• Angle of drop 0of pendulum =90
  
• Effective weight of pendulum=21.79kg
  
• Minimum value of scale graduation=2 Joules.
  
• Permissible total friction loss of corresponding energy=0.50%
  
• Distance from the axis of rotation of distance between the base of specimen notch and the point of specimen hit by the hammer=22mm±0.5mm
  

The longitudinal axes of the test piece shall lie in the plane of swing of the center of gravity of the hammer. The notch shall be positioned so that it is in the plane of the hammer .the notch shall be positioned its plane of symmetry coincides with the top face of the grips .for setting the specimen the notch impact strength I is calculated according to the following relation.

Where I= impact strength in joules/m²

PROCEDURE:

1. For conducting charpy test, a proper striker is to be fitted firmly to the bottom of the hammer with the help of the clamming piece.
   
2. The latching take for charpy test is to be firmly fitted to the bearing housing at the side of the columns.
   
3. The frictional loss of the machine can be determined by free fall test, raise the hammer by hands and latch in release the hammer by operating lever the pointer will then indicate the energy loss due to friction. From this reading confirm that the friction
   

loss not exceeding 0.5% of the initial potential energy. Otherwise frictional loss has to be added to the final reading.

1. The specimen for izod test is firmly fitted in the specimen support with the help of clamping screw and élan key. Care should be taken that the notch on the specimen should face to pendulum striker.
   
2. After ascertaining that there is no person in the range of swinging pendulum, release them pendulum to smash the specimen.
   
3. Carefully operate the pendulum brake when returning after one swing to stop the oscillations.
   
4. Read-off position of reading pointer on dial and note indicated value.
   
5. Remove the broken specimen by loosening the clamping screw.
   
6. The notch impact strength depends largely on the shape of the specimen and the notch. The values determined with other specimens therefore may not be compared with each other.
   

TABLE:

PRECAUTIONS:

1. Measure the dimensions of the specimen carefully.
   
2. Locate the specimen (Charpy test) in such a way that the hammer. Strikes it at the middle.
   
3. Note down readings carefully.
   

RESULT: The Impact strength of material by Charpy test………

VIVA QUESTIONS:

1. What is resilience? How is it different from proof resilience and toughness?
   
2. The ability of the material to resist stress without failure is called?
   
3. The impact test is done to test of a material?
   
4. In Charpy impact test, the specimen is kept as?
   
5. In charpy test specimen, the angle of v-notch section is?
   

APPLICATIONS:

In forging industry:

The Charpy impact test can be used to determine the malleability and ductility of a material that is being forged.

In plastic industry,

The test is used for analyzing the breaking strength of a sample when it is subjected to a high impact from a pendulum. This helps in ensuring that the material is best for an application where it is subjected to such impacts.