Ý. SAHIN et al.: EFFECTS OF SUBZERO TREATMENTS ON THE MECHANICAL PROPERTIES ...
489–494
EFFECTS OF SUBZERO TREATMENTS ON THE MECHANICAL
PROPERTIES OF THE SAE 4140 STEEL
VPLIV GLOBOKE PODHLADITVE SAE JEKLA 4140 NA NJEGOVE
MEHANSKE LASTNOSTI
Ýsmail Sahin
1*
, Gürhan Höke
2
, Henifi Çinici
3
, Tayfun Fýndýk
3
, Haluk Koralay
4
,
Uður Arabacý
3
1
Gazi University, Department of Industrial Design Engineering, 06550 Ankara, Turkey
2
Turk Traktor Company, Anadolu Avenue No. 52–52A, 06560 Ankara, Turkey
3
Gazi University, Department of Metallurgical and Materials Engineering, 06550 Ankara, Turkey
4
Gazi University, Department of Physic, 06550 Ankara, Turkey
Prejem rokopisa – received: 2018-07-04; sprejem za objavo – accepted for publication: 2019-01-17
doi:10.17222/mit.2018.135
In this study, effects of holding in liquid nitrogen and cryogenic methods applied onto the SAE 4140 steel were empirically
investigated. In this context, austempering, holding in liquid nitrogen, the conventional cryogenic process and tempering
processes were applied in different orders and combinations. The temperature of the samples to be tempered in liquid nitrogen
was decreased from room temperature to –196 °C at the average rate of 1.6 °C/min and held at this temperature for 24 h. The
temperature of the samples to undergo the traditional cryogenic process was decreased from room temperature to –140 °C at a
constant rate of 2 °C/min and held at this temperature for 24 h. After a microhardness analysis and tensile tests, it was observed
that the toughness was increased without the hardness being changed during both cooling processes carried out after austem-
pering processes. The most obvious improvement in terms of toughness was observed on the samples, to which austempering
was applied, exibiting an increase of 32.83 %, followed by the samples undergoing the cryogenic process and, lastly, the ones
undergoing the tempering process. The largest increase in the tensile strength also occurred in the samples subjected to
austempering, exhibiting a 66 N/mm
2
improvement. In terms of the properties investigated during this study, it was seen that the
process of holding steel in liquid nitrogen could consitute an alternative to the cryogenic process using different rates.
Keywords: SAE 4140, cryogenic process, liquid nitrogen, XRD (X-ray diffraction)
V {tudiji avtorji opisujejo empiri~no raziskavo vpliva zadr`evanja jekla SAE 4140 v teko~em du{iku in raziskavo kriogenih
tehnik. V zvezi s tem so izvajali razli~ne procese, kot so austempering, zadr`evanje v teko~em du{iku, konvencionalni kriogeni
procesi in popu{~anje v razli~nem redosledu. Vzorce jekla so po kaljenju ohlajali v teko~em du{iku s sobne temperature na
temperaturo –196 °C s povpre~no hitrostjo 1,6 °C/min in jih na kon~ni temperaturi podhladitve zadr`evali 24 ur. Vzorce, ki so
jih obdelali po konvencionalnem kriogenem postopku so ohlajali s sobne temperature na –140 °C s konstantno hitrostjo 2 °C/min in
jih na temperaturi podhladitve ravnotako zadr`evali 24 ur. Po teh krio- obdelavah so izvedli natezne preizkuse in meritve
mikrotrdote. Ugotovili so, da je v vseh izvedenih primerih podhlajanja, katerim je sledil {e postopek austemperinga,narasla
`ilavostne da bi se pri tem bistveno spremenila trdota jekla. Najbolj o~itna-32,83 %- izbolj{ava je bila vidna pri vzorcih pri
katerih je bil izveden austempering postopek, ki je sledil kriogenemu procesu in na katerih je bil izveden tudi postopek
popu{~anja. Ti vzorci so imeli tudi najvi{jo natezno trdnost z izbolj{anjem za 66 N/mm
2
. Glede na izvedene raziskave avtorji
ugotavljajo, da proces zadr`evanja v teko~em du{iku lahko predstavlja alternativo konvencionalnim kriogenim postopkom.
Klju~ne besede: SAE jeklo 4140, proces podhladitve, teko~i du{ik, rentgenska difrakcija (XRD)
1 INTRODUCTION
Materials for manufacturing mechanical systems are
used under difficult conditions such as excessive load
and high speed.
1
The selection of the materials used in
the making of machine parts and the heat treatment
applied to these materials are directly related to the
economic life of a machine.
2–4
Through a cryogenic
process, which is a type of heat treatment that can be
applied to steel, requiring low temperatures, it is possible
to turn the whole of the material’s structure into mar-
tensite and increase the toughness.
5
The SAE 4140 (42CrMo4) steel, having a wide area
of use in the machine-manufacturing industry, is a type
of steel with a high hardenability thanks to the alloys it
contains and it can demonstrate high toughness under
certain loads following the austempering process.
6
The
SAE 4140 steel can provide mechanical properties such
as strength, hardness and toughness under suitable heat-
treatment conditions.
7,8
The AISI 4100 grade steels are
also called low-alloy structural steels, forged steels,
medium-carbon steels and alloy steels. These steels are
used for crankshafts, axle shafts and sleeves, spline
shafts, gear wheels, cold-drawn shafts and rods, machine
steels, springs, turbine engines, brake rings and levers of
turbo generators, chains and anchors of ships, railway
wheels and shafts, starter gears and many other parts.
In the 1950s, tool manufacturers tried the process of
immersing and holding tools in liquid nitrogen, which
was the starting point of the cryogenic process, a new-
generation heat-treatment method. However, this method
resulted in damage to the tools due to thermal shocks.
Materiali in tehnologije / Materials and technology 53 (2019) 4, 489–494 489
UDK 620.1:536.421.48:691.714:67.017 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 53(4)489(2019)
*Corresponding author's e-mail:
isahin@gazi.edu.tr

Thus, more effective and controlled techniques were
developed, including programmable temperature con-
trollers to reduce the likelihood of a thermal shock, a
solenoid valve to control the flow of liquid nitrogen, and
a thermocouple to display the temperature of the work-
piece; thus, cryogenic processing systems used today
were formed.
A cyrogenic process, widely used in recent years, is a
heat-treatment process applied to strengthen the mecha-
nical properties of materials. A cryogenic process has
many application areas from space research to food
transportation.
9
Similarly, it can modify cutting-tool tips,
carburization and cementation steels used for gears, HSS
steels and AISI 4340 steels by increasing the resistance
to cracking, tool life, hardness, resistance to wear and
tear and fatigue strength.
10–18
From the research reported on in the literature, it is
seen that the effects of the process of holding steel in
liquid nitrogen or cryogenic process on the mechanical
properties of the SAE 4140 steel have not been inves-
tigated. Any improvement to the SAE 4140 steel, having
a wide area of use in the production of important me-
chanisms in the industry such as rail steel and gears, and
transmission mills in particular, would provide signifi-
cant advantages for industrial applications.
The process of holding in liquid nitrogen aims at sim-
plifying the cryogenic process, turning it into a heat-
treatment method that is more accessible. Thus, mid-
scale enterprises would be able to organise this process
within their organisations with smaller investments and
this process would be popularised. With this purpose in
mind, the effects of the process of holding in liquid
nitrogen (HPLN) and the cryogenic process (CP) on the
mechanical properties of the SAE 4140 steel were in-
vestigated individually in this study. This is a pioneering
study. XRD analyses of the crystallographic structures
obtained with the HPLN and CP processes were also
made.
2 MATERIALS AND METHODS
SAE 4140 steel bars, 12 mm in diameter and 6 m in
length, were used in the study. The samples taken from
these bars were first chemically analysed. In the wake of
the analyses, it was noticed that the material was
42CrMo
4
(SAE 4140) and the bars used were of the same
batch (Table 1).
Table 1: Chemical compositions of SAE 4140 samples
Element
Standard
range
Sample 1 Sample 2 Sample 3
% C 0.35–0.44 0.445 0.442 0.444
% Si 0.15–0.35 0.263 0.267 0.262
% Mn 0.60–0.90 0.802 0.807 0.801
% P 0.0–0.040 0.017 0.015 0.017
% S 0.0–0.040 0.026 0.024 0.026
% Cr 0.8–1.10 0.934 0.936 0.931
% Mo 0.15–0.25 0.194 0.193 0.193
Following the chemical analysis, the samples were
prepared for a microhardness analysis and tensile-
strength test on CNC lathes. For the tensile tests, five
samples were manufactured for each variant, 40 in total,
in line with the TS EN ISO 6892-1 standard.
19
A Dartec
25-ton-capacity universal tensile test bench was used for
the tensile tests. These tests were carried out at room
temperature, with a 3-N preload at a speed of 5 mm/min.
In order to analyse the impacts of the austempering
process, the process of holding in liquid nitrogen, the
cryogenic process and the tempering process on the
mechanical properties of the SAE 4140 steel, eight
different variants were produced in each step. These
variants are given in Table 2.
For the austempering process, the samples were held
at 850 °C for 185 min and subjected to a hardening pro-
cess cooling them down at 80 °C in oil. After the
hardening process, the tempering process was applied at
230
°
C for 60 min.
During the experiments conducted as part of the
study, a cryogenic-process system based on PLC con-
trolled direct cooling was used. The temperature of
Variants 3, 6 and 8 was reduced from ambient tempe-
rature to –140 °C at an average speed of 2 °C/min to
apply the cryogenic process and they were kept at that
temperature for 24 h. After 24 h, the temperature was
allowed to rise to ambient temperature again at an
average speed of 2 °C/min. During the process of
holding in liquid nitrogen, the cooling period of the
samples was recorded in 30-sec intervals by means of a
FLUKE 51-II model thermometer and FLUKE T-type
thermocouple.
Table 2: Heat-treatment methods applied and variants produced
Raw
(R)
Austem-
pering
(A)
Process of
holding in
liquid nitrogen
(HPLN)
Cryogenic
process
(CP)
Tem-
pering
(TE)
Variant 1  Variant 2  Variant 3  Variant 4  Variant 5 
Variant 6
Variant 7  
Variant 8 
The temperature of Variants 2, 5 and 7 was reduced
from ambient temperature to –196 °C at an average
speed of 1.5 °C/min to apply the process of holding in
liquid nitrogen and the samples were kept at this tem-
perature for 24 h. At the end of 24 h, the temperature
was allowed to rise to ambient temperature again at the
average speed of 1.5 °C/min.
Microhardness measurements were made on a Dura-
Scan computer-controlled Vickers-microhardness me-
asuring device. The measurements were made in inter-
Ý. SAHIN et al.: EFFECTS OF SUBZERO TREATMENTS ON THE MECHANICAL PROPERTIES ...
490 Materiali in tehnologije / Materials and technology 53 (2019) 4, 489–494

vals using 1-kg loads and a dimond, square-pyramid tip
with an apex angle of 136°.
XRD analyses of the variants were made using ra-
diation Cu-K
 ( = 1.5418 nm) on a computer-controlled,
Broker D8 advance-model powder diffractometer. The
measurements were taken at a scanning speed of 2 °/min
and at intervals of 2 = 10° to 90°. The analyses of the
peaks obtained from these patterns were compared to the
data of the International Centre for Diffraction Data
(ICDD).
3 RESULTS AND DISCUSSION
It was confirmed that when the process of holding in
liquid nitrogen or the cryogenic process are applied
individually, they have no significant effect on the raw
material. Therefore, the values obtained for Variants 1, 2
and 3 relating to the tensile strength, toughness resist-
ance and microhardness did not surpass the initial con-
ditions. The process of holding in liquid nitrogen pro-
vided a certain level of improvement of the austempered
samples. However, the principal effective results were
obtained as a result of the cryogenic process and addi-
tional tempering applied after the austempering process.
Hence, it was confirmed that the cryogenic process was
effective provided that it was applied after the austem-
pering process. Studies reported on in the literature
corroborate this phenomena. Researchers remarked that
the cryogenic process is a supplementary process applied
after the conventional heat treatment and not a process
that could replace heat treatment.
5,20
3.1 Microhardness measurements
With the purpose to investigate the effects of the
HPLN and CP on the change in the hardness of the SAE
4140 steel, microhardness measurements were made.
Using the Vickers-hardness measuring methods, a total
of 103 hardness measurements were taken, that is 13
measurements for each sample in the directions and in-
tervals shown in Figure 1. The average hardness values
calculated for each variant in each direction are given in
Table 3.
It was seen that the HPLN or CP applied onto the raw
SAE 4140 steel had no significant effect in terms of
hardness. The microhardness values obtained with the
purpose to individually analyse the effects of the pro-
cesses applied onto the samples after austempering were
(589, 587, 588 and 600) for Variants 5, 6, 7 and 8, res-
pectively. As it is obvious from the percentages of the
changes given, no significant increase was noticed for
the variants, apart from Variant 8. These obtained values
are higher than the hardness value of the SAE 4140 steel,
to which no austempering was applied and which cooled
down in a furnace, air or oil after the austempering at a
temperature of 840 °C.
21,22
It is known that the distribution characteristics,
dimensions, quantity and inter-particle distances of the
austenite and martensite in the structure of steel affect
the mechanical properties of the material. The graph
from Figure 2 was obtained as a result of the martensite
volume ratio analyses conducted in accordance with the
ASTM E562-02 standard using the microstructure pic-
tures given in Figure 1. It was confirmed that the resi-
dual austenite was converted into martensite in certain
ratios in all the samples, onto which the PSLN or CP
Ý. SAHIN et al.: EFFECTS OF SUBZERO TREATMENTS ON THE MECHANICAL PROPERTIES ...
Materiali in tehnologije / Materials and technology 53 (2019) 4, 489–494 491
Table 3: Microhardness data (R: raw, HPLN: holding process in liquid nitrogen, CP: cryogenic process, A: austempering, TE: tempering)
Microhardness
N/mm²
Var 1:
R
Var 2:
HPLN
Var 3:
CP
Var 4:
A
Var 5:
A+HPLN
Var 6:
A+CP
Var 7:
A+HPLN+TE
Var 8:
A+CP+TE
Average 334 339 334 583 589 587 588 600
Figure 1: Microstructure images depending on the processes applied to the variants

were applied after austempering. The increase in the
volume during the conversion of the residual austenite
into martensite causes deformation of the martensite and
dislocations in the structure, associated with the
deformation resulting from this increase in the volume,
form nucleation zones for thin carbides that are depo-
sited by the tempering applied after the cryogenic
treatment (Figure 2).
23,24
At the same time, it is believed
that some of the effects caused by the carbide decom-
position that occurs during the cryogenic process or the
changes in the carburized layer within the structure cause
partial changes in the hardness.
25
It is known that austempering and the increase in the
hardness occurring with the tempering applied after aus-
tempering increases the wear resistance.
26
Therefore, it is
thought that the HPLN and CP processes applied after
austempering and increasing the hardness values would
cause the wear resistance to get even higher.
3.2 Tensile strenght
It was seen that the tensile strentgh of Variant 1,
which was not treated with the purpose to investigate the
effects of the HPLN and CP on the SAE 4140 steel in
terms of tensile strength, was relatively higher than the
values of Variants 2 and 3. The largest increase in the
tensile strength during the studies conducted with the
purpose to reveal the effects of the HPLN and CP
applied after the austempering was noticed for Variant 8
(Table 4). This was followed by Variant 7.
In order to analyse the effects of the HPLN and CP
on the raw SAE 4140 in terms of tensile strength, the
percentages of the changes in the tensile strength calcul-
ated with reference to Variant 1, onto which no processes
were applied, were calculated to be –0.69 % and –1.31 %
for Variants 2 and 3, respectively. However, to demon-
strate the effects of the HPLN and CP for the cases when
they were applied after the treatment process, the per-
centages of the changes in the tensile strength were
calculated with reference to Variant 4, which had been
treated. The changes in the percentages calculated for
Variants 5, 6, 7 and 8 were calculated to be (–0.32, 0.05,
0.69 and 3.49) %, respectively. As can be understood
from these percentage-change values, the highest in-
crease in the tensile strength occurred for Variant 8,
amounting to 3.49 %. This was followed by Variant 7
with 0,69 %.
3.3 Toughness
Toughness data was calculated with the help of
Equation (1) based on the results of the tensile-strength
test:

 ⋅
∫
d
0
k
(1)
Based on the average toughness calculated from the
toughness values given in Table 5, we can say that the
toughness-resistance values for Variants 1, 2 and 3 are
very similar, while the values obtained for Variants 4, 5,
6 and 7 are higher. The highest roughness value was ob-
tained for Variant 8.
An increase in the toughness of the samples sub-
jected to the holding process in liquid nitrogen amounted
only to an average ratio of 6.33 %, and an average ratio
of 22.76 % was recorded for the samples subjected to the
cryogenic process. The most significant reason for this
high performance of the CP compared to the HPLN in
terms of an increase in the toughness is the fact that the
cryogenic process ensures a more stable structure by
helping to remove the stresses from the material struc-
ture through a linear temperature change.
5,16,20
On the
other hand, for the HPLN, it is not possible to find a
fully linear behaviour when the temperature is on a de-
crease or on an increase back to ambient temperature.
3.4 XRD analysis
The patterns obtained through the XRD analyses
conducted to investigate the effects of the HPLN and CP
Ý. SAHIN et al.: EFFECTS OF SUBZERO TREATMENTS ON THE MECHANICAL PROPERTIES ...
492 Materiali in tehnologije / Materials and technology 53 (2019) 4, 489–494
Figure 2: Martensite volume ratio analysis
Table 4: Tensile-strenght data (R: raw, HPLN: holding process in liquid nitrogen, CP: cryogenic process, A: austempering, TE: tempering)
Tensile Joule
Var 1:
R
Var 2:
HPLN
Var 3:
CP
Var 4:
A
Var 5:
A+HPLN
Var 6:
A+CP
Var 7:
A+HPLN+TE
Var 8:
A+CP+TE
Average 1145 1137 1130 1891 1885 1890 1904 1957
Table 5: Toughness data (R: raw, HPLN: holding process in liquid nitrogen, CP: cryogenic process, A: austempering, TE: tempering)
Toughness
N/mm²
Var 1:
R
Var 2:
HPLN
Var 3:
CP
Var 4:
A
Var 5:
A+HPLN
Var 6:
A+CP
Var 7:
A+HPLN+TE
Var 8:
A+CP+TE
Average 64.165 61.943 61.007 108.015 113.403 121.714 116.312 143.476

on the SAE 4140 steel are given in Figure 3. The phase
of the treated layer was analyzed with XRD, using Cu-K
 radiation. A diffractometer with radiation with a wave-
length of 0.15418 nm having a nickel filter, equipped
with an X-ray generator was used. Figure 3 shows the
XRDs of the samples evaluated through an X-ray study
of diffraction patterns by means of a software database
of JCPDS (Joint Committee on Powder Diffraction Stan-
dards). The XRD analysis represents almost entirely the
a-phase (Fe-BCC).
The crystallite sizes of the prepared samples were
calculated using the Scherrer equation (Equation 2)
27
where L
hkl
is the size of crystallite, is the wavelength of
the x-ray source used,  is the full width at half maxi-
mum (FWHM) of the peaks of the x-ray patterns, and  is the peak angle:
L
hkl
=
09 .
cos
 
(2)
Crystallite sizes provide information on the quality of
crystallites and are inversely proportional to the full
width half maximum of diffraction peaks obtained with
XRD. A diffraction peak, being rather narrow, makes the
crystallite size bigger and this demonstrates that the
crystallite has a quality structure.
28
When the data from
Table 6 and Figure 4 is analysed, it is seen that the
HPLN and CP applied onto the samples decrease the
sizes of the crystallines.
4 CONCLUSIONS
As part of the study, effects of the process of holding
in liquid nitrogen and conventional cryogenic process on
the hardness, tensile strength and toughness of the SAE
4140 steel were analysed and compared to one another.
The following findings were obtained:
It was seen that applying only the HPLN and CP on
the raw SAE 4140 steel had no effect on the toughness,
microhardness and tensile strength of the material.
HPLN and CP processes caused the tensile strength
to partially decrease compared to that of the raw mate-
rial, and the HPLN and CP applied after austempering
had the same effect compared to the samples that under-
went austempering only. However, when tempering was
applied after austempering + HPLN or austempering +
CP, it caused the tensile strength to increase. It is thought
that the tempering applied as the last process removes
the stress from the structure and consequently increases
the tensile strength.
Austempering, the CP and HPLN applied after the
austempering and tempering processes caused crystalline
sizes to decrease (Figure 4). The reason for the increase
in the hardness, tensile strength and toughness resistance
may also be explained with the decrease in crystalline
sizes.
The best performance in terms of tensile strength was
found for Variant 8, which underwent austempering +
CP + tempering. This variant was followed by Variant 7,
which underwent austempering + HPLN + tempering.
It is thought that the HPLN and CP cause the average
crystalline sizes to decrease; therefore, they cause the
force of gravity between the atoms and increase the
toughness resistance and tensile strength.
The process of holding in liquid nitrogen drew near
to the conventional cryogenic process by:
a) 99.40 % in the concentric performance,
b) 98.49 % in the tensile-strength performance,
c) 27.81 % in the toughness performance,
d) 52.22 % in the hardness performance.
Ý. SAHIN et al.: EFFECTS OF SUBZERO TREATMENTS ON THE MECHANICAL PROPERTIES ...
Materiali in tehnologije / Materials and technology 53 (2019) 4, 489–494 493
Figure 4: Changes in the crystalline size
Figure 3: XRD data representing effects of HPLN and CP on SAE
4140 steel
Table 6: Average particle (crystalite) sizes
Var 1:
R
Var 2:
HPLN
Var 3:
CP
Var 4:
A
Var 5:
A +HPLN
Var 6:
A+CP
Var 7:
A+HPL+TE
Var 8:
A+ CP +TE
Crystalline
size (nm)
4.391 3.948 4.066 3.729 3.550 3.357 3.090 3.085

Acknowledgement
This research was funded by the Projects of Scientific
Investigation Unit of Gazi University (project code
07/2012-55).
5 REFERENCES
1
ª. Ekinci, A. Akdemir, Effect of applied load on the wear rate of
nitrided AISI 4140 steel, Selçuk Teknik Dergi, 10 (2011) 1, 38–52
2
S. Ulu, H. Aytekin, G. Said, The effect of the heat treatment between
A1 and A3 in the Fe-Fe3c phase diagram on the some mechanical
properties of four different steels, Makine Teknolojileri Elektronik
Dergisi, 2 (2006), 1–9
3
Catalog of the MKE special grade steel types, MKE Printing House,
Ankara 1978, 5
4
G. Höke, Comparison of effects of holding in liquid nitrogen and
traditional cryogenic processes on mechanical and microstructure
properties of SAE 4140 steel, Msc Thesis, Gazi University Graduate
School of Natural and Applied Sciences, Ankara,2014
5
F. K. Arslan, The effect of sub-zero treatment on the mechanical pro-
perties of cold work tool steels, Msc Thesis, Sakarya University
Graduate School of Natural and Applied Sciences, Sakarya 2010, 82
6
E. Kesti, Investigation of effects of quenching media on micro-
structure and mechanical properties of 4140 steel, Msc Thesis,
Selçuk University Graduate School of Natural and Applied Sciences,
Konya 2009, 14–23
7
S. H. Avner, Introduction to Physical Metallurgy, McGraw Hill Book
Company, 2. Ed., 1986,New York, 315–336
8
S. Choo, S. Lee, M. G. Golkovski, Effects of accelerated electron
beam irradiation on surface hardening and fatigue properties in an
Ç-4140 steel used for automotive crankshaft, Materials Science and
Engineering A 293, (2000), 56–70
9
Y. Yildiz, The effects of cold and cryogenically treated copper elec-
trodes and beryllium-copper alloy workpieces on the performance of
electro discharge machining, PhD Thesis, Gazi University Graduate
School of Natural and Applied Sciences, Ankara 2010, 65
10
V. Firouzdor, E. Nejati, F. Khomamizadeh, Effect of deep cryogenic
treatment on wear resistance and tool life of M2 HSS drill, Journal of
Materials Processing Technology, 206 (2008), 467–472, doi:10.1016/
j.jmatprotec.2007.12.072
11
K. H. W. Seah, M. Rahman, K. H. Yong, Performance evaluation of
cryogenically treated tungsten carbide cutting tool inserts, Journal of
Engineering Manufacture, 217 (2003), 29–43, doi:10.1243/
095440503762502260
12
M. Preciado, P. M. Bravo, J. M. Alegre, Effect of low temperature
tempering prior cryogenic treatment on carburized steels, Journal of
Materials Processing Technology, 176 (2006), 41–44, doi:10.1016/
j.jmatprotec.2006.01.011
13
S. Harish, A. Bensely, D. Mohan Lal, A. Rajadurai, G. B. Lenkey,
Microstructural study of cryogenically treated En 31 bearing steel,
Journal of Materials Processing Technology, 209 (2009)7 ,
3351–3357, doi:10.1016/j.jmatprotec.2008.07.046
14
S. Zhirafar, A. Rezaeian, M. Pugh, Effect of cryogenic treatment on
the mechanical properties of 4340 steel, Journal of Materials Pro-
cessing Technology, 186 (2007), 298–303, doi:10.1016/j.jmatprotec.
2006.12.046
15
D. Das, A. K. Dutta, K. K. Ray, Optimization of the duration of cryo-
genic processing to maximize wear resistance of AISI D2 steel,
Cryogenics, 49 (2009), 176–184
16
P. Baldissera, C. Delprete, Effects of deep cryogenic treatment on
static mechanical properties of 18NiCrMo5 carburized steel, Mater-
ials and Design, 30 (2009), 1435–1440, doi:10.1016/j.matdes.
2008.08.015
17
A. Bensely, D. Senthilkumar, D. Mohan Lal, G. Nagarajan, A.
Rajadurai, Effect of cryogenic treatment on tensile behavior of case
carburized steel 815M17, Materials Characterization, 58 (2007),
485–491, doi:10.1016/j.matchar.2006.06.019
18
L. Shyamala, A. Bensely, S. Harish, D. Mohan Lal, G. Nagarajan, K.
Junik, A. Rajadurai, Fatigue behaviour and fracture mechanism of
cryogenically treated En 353 steel, Materials and Design, 30 (2009),
2955–2962, doi:10.1016/j.matdes.2009.01.003
19
TS EN ISO 6892–1:2011 Technical product documentation, Metallic
materials - tensile tests - part 1: Test method at room temperature,
TSE Publications, Ankara
20
T. Kivak, Investigation of the effect of cryogenic treatment applied
on cutting tools on drillability of Ti-6Al-4V alloy, PhD Thesis, Gazi
University, Ankara 2012, 36–39
21
P. Starke, P. Walther, D. Eifler, New fatigue life calculation method
for quenched and tempered steel SAE 4140, Materials Science and
Engineering: A, 523 (2009) 1–2, 246–252, doi:10.1016/j.msea.
2009.05.067
22
S. Sitthipong, P. Towatanab, A. Sitticharoenchaic, C. Meengamd,
Abrasive wear behavior of surface hardfacing on propeller shafts
AISI 4140 alloy steel, Materials Today: Proceedings, 4 (2017),
1492–1499, doi: 10.1016/j.matpr.2017.01.171
23
F. K. Arslan, The effect of sub-zero treatment on the mechanical
properties of cold work tool steels, Msc Thesis, Sakarya University,
Sakarya 2010, 41–53
24
T. Kývak, Investigation of the effect of cryogenic treatment applied
on cutting tools on drillability ti-6Al-4V alloy, PhD Thesis, Gazi
University, Ankara 2012, 36-39
25
P. Baldissera, C. Delprete, Effects of deep cryogenic treatment on
static mechanical properties of 18NiCrMo5 carburized steel, Mater-
ials and Design, 30 (2009), 1435
26
A. Sebhi, N. Douib, Wear behavior of a low-alloy (AISI-SAE) 4140
steel after quenching and tempering, Materials Today: Proceedings, 3
(2016), 2841–2852, doi:10.1016/j.matpr.2016.07.003
27
B. D. Cullity, S. R. Stock, Elements of X-ray Diffraction, 2
nd
ed.,
Addison–Wesley 1978
28
T. Savaskan, Material knowledge and inspection, 5
th
ed., Karadeniz
Technical University Publishing, Trabzon 2009, 49–63
Ý. SAHIN et al.: EFFECTS OF SUBZERO TREATMENTS ON THE MECHANICAL PROPERTIES ...
494 Materiali in tehnologije / Materials and technology 53 (2019) 4, 489–494