Name:
ID No:
Branch:
AZHAAN AZAA ANVER
2020A4PS0496P
MECHANICAL ENGINEERING
----------------------------------------------------------------------------------------------Experiment 3
Objective: To interpret ductile brittle behaviour of different metals from the absorbed
energy during impact test.
Requirements for the experiment
1.
2.
3.
4.
5.
6.
7.
V-notched specimen
Swing pendulum Impact Testing Machine
Liquid nitrogen
Optical pyrometer
Temperature controller heater
Water
Stopwatch
Theory:
In materials science and metallurgy, toughness is the ability of a material to absorb energy and
plastically deform without fracturing. Various types of notched-bar impact tests are used to
determine the tendency of a material to behave in a brittle manner. A large number of notchedbar test specimens of different design have been used by investigators of the brittle fracture of
metals. Two classes of specimens have been standardized^ for notched-impact testing. Charpy
bar specimens are used most commonly in the United States, while the Izod specimen is
favoured in Great Britain. The Charpy specimen is supported as a beam in a horizontal position.
The load is
applied by the impact of a heavy swinging pendulum (approximately 16 ft /sec impact velocity)
applied at the midspan of the beam on the side opposite from the notch. The specimen is forced
to bend and fracture at a strain rate on the order of 10* in. /(in.) (sec). The Izod specimen is
either circular or square in cross section and contains a V notch near one end. The specimen is
clamped vertically at one end like a cantilever beam and is struck with the pendulum at the
opposite end. The response of a specimen to the impact test is usually measured by the energy
absorbed in fracturing the specimen. Impact results are frequently expressed in energy absorbed
per unit cross-sectional area of the specimen.
Experimental procedure :
1. First of all, places the indenter on the dial to the maximum reading and release the
pendulum. The indenter will go to zero position. This is to ensure that there is no
error in the dial.
2. Keep the specimen at the bottom of the machine (horizontally for Charpy test and
vertically for Izod test). The notch of the specimen should remain behind to the
impact load of the swing pendulum.
3. Now indenter will move towards zero end of the scale. Count the number of division
from zero to the position of the indenter after impact. This will give the energy of the
specimen absorbed by impact of the pendulum.
CHARPY
IZOD
IMPACT TEST MACHINE
Observation table:
Dimension of Test specimen: Cross -section of specimen- Square (10 mm * 10 mm)
Cross section of specimen at notch – Rectangular (10 mm * 8 mm)
Depth of Notch- 2mm
Izod test:
SPECIMEN
MATERIAL
WIDTH OF
SPECIMEN
THICKNESS
OF SPECIMEN
DEPTH OF
NOTCH
ALUMINUM
10
10
2
IMPACT
ENERGY
(JOULES)
25
IMPACT STRENGTH
AT NOTCH
BRASS
10
10
2
12
150 𝑘𝐽/𝑚
COPPER
10
10
2
62
775 𝑘𝐽/𝑚
MILD STEEL
10
10
2
158
1975 𝑘𝐽/𝑚
312.5 𝑘𝐽/𝑚
Charpy test:
SPECIMEN
MATERIAL
WIDTH OF
SPECIMEN
10
THICKNESS
OF
SPECIMEN
10
DEPTH
OF
NOTCH
2
IMPACT
ENERGY
(JOULES)
22
ALUMINUM
IMPACT
STRENGTH AT
NOTCH
BRASS
10
10
2
15
187.5 𝑘𝐽/𝑚
COPPER
10
10
2
65
812.5 𝑘𝐽/𝑚
MILD STEEL
10
10
2
150
1875 𝑘𝐽/𝑚
275 𝑘𝐽/𝑚
Calculation: To find the Impact strength at the notch for different specimen.
Area of cross section = (10-2)mm*10mm = 80mm2
We know that, Impact Strength =
For IZOD TEST:
IMPACT STRENGTH
1. Aluminium =
2. Brass =
3. Copper =
4. Mild Steel =
= 312.5 𝑘𝐽/𝑚
= 150 𝑘𝐽/𝑚
= 775 𝑘𝐽/𝑚
= 1975 𝑘𝐽/𝑚
For CHARPY TEST:
IMPACT STRENGTH
1. Aluminium =
2. Brass =
3. Copper =
4. Mild Steel =
= 275 𝑘𝐽/𝑚
= 187.5 𝑘𝐽/𝑚
= 812.5 𝑘𝐽/𝑚
= 1875 𝑘𝐽/𝑚
Results:
We can see that the order of strength
Mild Steel > Copper > Aluminium > Brass