Google Search

Wednesday, March 30, 2011

BRINELL HARDNESS TEST


BRINELL HARDNESS TEST



Aim:

To determine the Brinell hardness number for the given specimen.

Apparatus Required:

1. Brinell hardness testing machine
2. Microscope
3. Indentor
4. Test specimen
5. Stop watch

Procedure:

1. Identify the material of the given specimen
2. Know the value of P/D2 and diameter of the indentor (D) type to be used for the given test specimen from the following table.

Sl.No.
Material type
P/D2value in kg/mm2
Diameter of steel ball (D)
indentor in mm
1
Steel and cast iron
30
2.5
2
Copper and Aluminum Alloys
10
2.5
3
Copper and Aluminum
5
2.5
4
Lead, Tin and Alloys
1
2.5

Wher, P = Major load in kg.

3. Calculate the major load to be applied for the given test specimen by knowing the value of PD2 and D.
4. Select the major load from the knob available on the right of the machine.
5. Fix the indentor and place the given specimen on the anvil of the machine.
6. Raise the anvil using the rotating wheel till the specimen touches the indentor and then slowly turns the wheel till the small pointer on the dial reaches the red mark position. Now the specimen is subjected to a minor load of 10kg.
7. Apply the major load to the specimen by pushing the loading – handle in the forward direction and allow the load to act on the specimen for 15 seconds.
8. Release the major load by pushing the loading handle in the backward direction.
9. Release the minor load of 10kg by rotating the hand wheel and lowering the screw bar.
10. Measure the diameter of indentation (d) using the microscope.
11. Calculate the Brinell hardness number for the given specimen using the following formula:



Brinell hardness number =          Load in kg
                                            Spherical area of Indentation of mm2

                                          =             P                               kg/mm2
                                                     πD/2 [d - √ D2 – d2]
Where, P = Major load in kg.
           D = Diameter of indentor in mm.
           d = diameter of indentation in mm.
12. Repeat the experiment to obtain at least 3 different sets of observations for the given specimen by giving a gap of at least 3mm between any two adjacent indentations and 1.5mm from the edge.
11. Find the average value, which will be the Brinell hardness number for the given specimen.

Result:
The Brinell hardness number for the given specimen = ----------- kg/mm2
Observation:
Sl.No.
Material
P/D2value in kg/mm2
Major load (P) in kg
Diameter of steel ball indentor (D) in mm.
Dia of indentation (d) in mm
Brinell hradmess number (BHN) in kg/mm2
















                                                           Average








0 comments:

Post a Comment