MATL913/MATE413 SEM report 1
Characterisation of fracture surface of plain ca
on steel samples Charpy impact tested at room
temperature and -80°C
1. Materials and mechanical properties
Fracture surfaces of two Charpy impact tested plain ca
on steel samples, at room temperature and
-80°C. The steel sample tested at RT show 11J fracture energy and the sample tested at -80°C show 1.2J
fracture energy.
2. SEM sample preparations
The fracture surfaces of the two steel samples were coated with Au before being inserted into a
SEM for observation. One optical sample was also cut from one of the Charpy samples and then
polished with 1µm diamond and followed by etching with 2% Nital to reveal the microstructure
3. SEM operation conditions
a. Instrument: JCM-6000
. Operations: A working distance of 35 mm and secondary electron imaging mode at 15
kV were chosen for the fracture surface observation. For the microstructure and EDS a
working distance of 15 mm and secondary imaging mode at 15 kV were chosen.
4. Results:
a. Fracture surfaces of the Charpy tested samples at room temperature and -80°C (see
appendix A)
. Microstructure and EDS of the steel (see appendix B)
c. Please note that you are required not only present the results but also to describe these
esults in details in order to lay a ground for your later discussions about your results.
(30 marks)
5. Discussions
The following questions should be addressed in the report:
a. Why the fracture surfaces are coated with Au? You need to discuss SEM sample
preparations in general as well. (10 marks)
. Why the working distance of 35 mm and secondary electrons were used for the fracture
surface observations? Discuss the effect of working on image quality, the image contrast
mechanisms in secondary electron images and in backscattered electron images.
(10marks)
c. Describe the characteristics of the ductile and
ittle fracture surface and explain how
the energy of the hammer of the Charpy tester was abso
ed by fracturing. (10 marks)
d. The composition of the steel was analysed with EDS. Is the ca
on content of the steel
determined by the EDS co
ect and why? (10 marks)
e. Comments on the general suitability and e
ors of EDS for determining light elements in
an alloy. (10 marks)
f. Determine the ca
on content using Fe-Fe3C phase diagram and lever rule combined
with the microstructure of the Charpy tested sample and from this result you should be
able to identify the type of ca
on steel used in the Charpy tests. (10marks)
g. At least 6 references are required in this report and they must be refe
ed in one of the
standards. (10 marks)
Appendix A: Fracture surface of Charpy tested samples
Fracture surface of Charpy sample tested at room temperature (RT)
Fracture surface of Charpy sample tested at room temperature (RT)
Fracture surface of Charpy sample tested at -80°C
Fracture surface of Charpy sample tested at -80°C
Appendix B: Microstructure and composition of the Charpy tested steel
51% pearlite and 49% Fe
ite are determined using the software called image J
(Image J software can be download free from https:
imagej.nih.gov/ij/ . User guide is available at
https:
imagej.nih.gov/ij/docs/index.html)
20 µm
Secondary electron image and area EDS microanalysis of the Charpy sample which is
polished with diamond and etched with 2% nital
JED-2300 AnalysisStation
50 µm50 µm50 µm50 µm50 µm
Title: SEM image and EDS
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Instrument : JCM-6000
Volt : 15.00 kV
Mag. : x 750
Date : 2020/03/27
Pixel : 1024 x 768
XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX
keV
0
800
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2400
3200
4000
4800
5600
6400
7200
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8800
9600
Co
un
ts
C
CKsum
Mg Si SiKsum
Mn
Mn
MnKesc
Mn
Mn
Fe
Fe
Fe
Acquisition Parameter
Instrument : JCM-6000
Acc. Voltage : 15.0 kV
Probe Cu
ent: XXXXXXXXXXnA
PHA mode : T2
Real Time : 52.15 sec
Live Time : 50.00 sec
Dead Time : 4 %
Counting Rate: 7077 cps
Energy Range : XXXXXXXXXXkeV
ZAF Method Standardless Quantitative Analysis
Fitting Coefficient : 0.0319
Element XXXXXXXXXXkeV) Mass% Sigma Atom% Compound Mass% Cation XXXXXXXXXXK
C K XXXXXXXXXX XXXXXXXXXX98 XXXXXXXXXX4.4740
Mg K XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX0.1709
Si K* XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX0.3377
Mn K* XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX0.8223
Fe K XXXXXXXXXX XXXXXXXXXX64 XXXXXXXXXX94.1951
Total XXXXXXXXXX XXXXXXXXXX