BRINELL HARDNESS TESTING

AIM OF THE EXPERIMENT :

To determine the Brinellhardness of given test specimen.

APPARATUS:

1. Brinell hardness testing m/c

SPECIFICATION:

Type-B-3000(h)

Load range-In stages of 250 kgf up to 3000kgf

Impresion depth gauge- An electric moter 0.25 Hp/0.33Hp flange mounted

Maximum test height-410mm

Depth of throat -200mm

Maximum depth of the spindle below base-180mm

Height -1127mm

Size of base-690x225mm

Net weight-450kg

Main supply -440/440v 3ф,50 cycle/sec

Mounting –Free base

2.Test specimen

3.Ball indenter o size ,10mm,5mm,and 2.5mm

4.Brinell microscope

5.Seven spanners

THEORY :

Standard brinell test is conducted as per ASTM(American Society of Testing Materials )specifications .For testing iron and steel , a load of 3000kg is applied on a 10 mm diameter ball indenter for atleast 10 sec and for non ferrous metals and alloys , a load of 500kg is applied on the same indentor for atleast 30 sec .The loads are gradually applied by means of hydraulic mechanism .The ball indenters are made of either high carbon steel or tungsten carbide.After full application of load for above times ,load is slowly

removed . The indenter is taken out and the dia of circular is measured by special microscope . This measuring instrument signifies the image and with the calibrated grid provided in the eye piece , measurement of dia is done with accuracy of 0.01mm.

Brinell hardness number is calculated as below :

B.H.N. = Load applied in kg/ Area of indentation in sq.mm

From the diameter of projected impression , the area of indentation can be calculated as below :

Let D=dia of indenter

d=dia of projected circular impression

h=depth of penetration due to application of load P

From measurement principles, the surface area of segment of sphere is equal to Dh

From figure, h = (D/2_x)

Again from right angle triangle OCB,

PROCEDURE:

For carrying out test the following procedure should be adopted carefully. Any negligence may need to spoil the indenter as well as m/c .

1. Keep the hand lever (29) at position A.

2. Start the motor and wait until the weight hanger reaches its top position.

3. Place the specimen securely on testing table.

4. Turn the hand wheel (1) in clockwise direction, so that specimen will push the indenter and show a reading o the dial gauge (15). The movement will continued until the long pointer will stop at “o” and small pointer at red dot. When the initial load of 250kgf is applied. If little error exists, the same can be adjusted by rotating the outer ring of dial gauge (15)

5. Turn the hand lever (29)from position A to B so that the total load is brought into actions.

6.When the long pointer of the dial gauge reaches a steady position ,the load may be released for normal production testing , or may be maintained for upto 15 sec for accurate work.

7.For releasing the load ,take back the lever (29)to “A”Positon . The weights are lifted off and the indenter will come to rest at required depth reading . Thus only initial load is remaining active.

8.Turnback the hand wheel (1)and remove the specimen ,carry out the same procedure for further specimen.

9.Then measure the dia of impression by Brinell microscope and find out the Brinell hardness number .

OBSERVATION

Test piece material =

Diameter of ball D=

P/D2=

Test load =

Load application time =

TABULATION :