The Charpy impact test determines the impact toughness or strength of a material by measuring the energy absorbed when a pendulum strikes a V-notched specimen. Testing was conducted on specimens at room temperature (24.3°C) and -40°C. The room temperature specimen absorbed more energy (17.33J) and was more ductile, while the -40°C specimen absorbed less energy (2.10J) and was more brittle. Impact toughness depends on temperature, with materials becoming more brittle at lower temperatures.

1. 1
CHARPY IMPACT TEST M.MANOGO
AIM
The Charpy impact test is used to determine the impact toughness or impact strength
of a certain specimen. The apparatus used are the Zwick Roel Charpy testing machine
and a V-Notch Charpy type specimen.
The impact toughness of metal is simply determined by measuring the energy
absorbed in the fracture of the specimen when the pendulum from the Charpy impact
test machine strikes the specimen placed between the anvils (lowa, 2008)
The toughness of metal is affected by temperature. The toughness of a material
is simply the area under the stress-strain graph. A Charpy test for a certain metal must
be done repeatedly, so this process produces a graph of impact toughness for a
material. At low temperatures, the material has low impact toughness and it is more
brittle while at high temperatures the material has high impact toughness and it is more
ductile.
TEST SAMPLE
The sample must be a V-Notch Charpy type specimen. According to the ASTM E23,
the sample must be 55mm wide and have a 10mm x 10mm square area on both
ends, the V-Notch must have a radius of 0,25mm with a 45° angle (Harbour, 2007)
Make sure the specimen has been placed in an environment of the correct
temperature. Measurement is done by the Vernier calliper and Shadow-graph which
measures the angle and radius of the notch.

2. 2
APPARATUS
The Zwick Roell Charpy RKP 450 impact testing machine
Photo
The name of the apparatus is the Zwick Roel Charpy impact testing equipment
(pendulum type). This equipment is going to help us determine the amount of energy
absorbed during fracture. The material’s notch toughness is measured by the
absorbed energy.
This whole process is a high-strain test, a swinging pendulum from a set height
strikes a standard notched specimen with a certain weight. (CSWIP, 2015) . The ASTM
E23 standard holds the principles of the Charpy impact test.

3. 3
TEST PROCEDURE
According to the ASTM E23 the first thing you must do is confirm the V-Notch
specimen, make sure the temperature and humidity are correct and stable. On the
Charpy impact testing machine move the pendulum up to its position and lock it.
(Holt, 1990).
Make sure all safety guards are in place and that you are wearing safety gear. Put
the specimen inside the machine supported by both sides in position against the
anvils, make sure the notch is facing in the opposite direction of the pendulum. When
you place the specimen make sure you use the correct equipment, do not do it with
your hands. Set the pointer to the correct scale. Now, close the machine and release
the pendulum, make sure there are no vibrations before you release the pendulum.
(SGS, 2014)
Record the information displayed and return the pendulum to its position and locked
it.
RESULTS
Specimen
ID
Temperature
(o
C)
Energy
Absorbed
(J)
Lateral
Expansion
Percentage
Shear (%)
1 24.3 17.33 ΔW = Wf –
Wi
= 10.21 -
9.96
= 0.25mm
%W = ΔAf –
ΔAi
= (10.21 x
10.03) –
(9.96 x
9.97)
= 3.11
2 -40 2.10 ΔW = Wf -
Wi
= 9.95 –
9.94
= 0.01
%W = ΔAf –
ΔAi
= (9.95 x
9.97) –
(9.94 x
9.96)
= 0.20

4. 4
DISCUSSION
The Charpy test determines whether a material is brittle or ductile. The test is
performed as precisely as possible. Based on the results acquired from the
experiment, the specimen at room temperature (24.3°C) required 19.7 J of impact
energy and it was more ductile, while at -40° C it required 3.6 J of impact energy and
it was more brittle.
Impact properties are not directly used in fracture mechanics calculations, but
the economic impact tests are used as a quality control method to asses notch
sensitivity and for comparing the relative toughness of engineering materials.
(metals, 2005)
It can also be used on polymers, ceramics and composites.
The absorbed energy is the energy absorbed in a material when it deforms
plastically, this is termed ductility’
Toughness is measured or calculated by the area under the stress or strain
graph. The key to toughness is a good ductility and strength, but just because a
material is ductile does not make it tough, so a material with high ductility and
strength will have more toughness than a material with low ductility and strength.
(Gupta & Brown , 2000).
The transition temperature is the temperature where a material change from
brittle to ductile, it is mostly found under the Charpy toughness vs temperature graph.
Charpy toughness and temperature

5. 5
References:
List all references used according to the prescribed standard (API)
CSWIP, 2015. TWI. [Online]
Available at: http://www.twi-global.com
[Accessed 31 March 2020].
Gupta, C. D. & Brown , G. A., 2000. Gate Dielectric Intergrity: Material, Process, and Tool
Qualifications. Journal of ASTM International, lll(12), pp. 33 - 37.
Harbour, B., 2007. Standard Test Methods for Notched Bar Impact Testing of Mettalic Materials,
Pennsylvania: ASTM International.
Holt, J. M., 1990. Charpy Impact Test: Factors and Variables. 3rd ed. Chelsea: ASTM International.
lowa, s. u., 2008. NDT Resource cemter. [Online]
Available at: http://www.nde-org
[Accessed 31 March 2020].
metals, S. o. i. t. o., 2005. Impact Testing of Metals. 4th ed. New York: ASTM International.
SGS, 2014. SGS. [Online]
Available at: http://www.msitesting.com
[Accessed 31 March 2020].