INTERNATIONAL MULTIDISCIPLINARY JOURNAL FOR
RESEARCH & DEVELOPMENT
SJIF 2019: 5.222 2020: 5.552 2021: 5.637 2022:5.479 2023:6.563 2024: 7,805
eISSN :2394-6334
https://www.ijmrd.in/index.php/imjrd Volume 12, issue 06 (2025)
114
SELECTION OF ALLOYS, THEIR STRUCTURE AND PROPERTIES
BoboyevX.X.
1
, Nurullayev R.T.
2
, Saydullayev A.Sh.
3
Dean of the Faculty
of Energy and Mechanical Engineering,
Almalyk Branch of Tashkent State Technical University named after Islam Karimov
Assistant Lecturer,
Department of Mechanical Engineering Technology,
Almalyk Branch of Tashkent State Technical University named after Islam Karimov
Student of group
7b-23MT, Department of Mechanical Engineering Technology,
Almalyk Branch of Tashkent State Technical University named after Islam Karimov
Annotation:
This study investigates the deformation behavior of various steels and alloys under
high-temperature and isothermal conditions. The effects of deformation rate, temperature, and
initial microstructure on the mechanical properties and microstructural changes during
deformation are analyzed. The use of isothermal conditions allows for improved control over
deformation processes, leading to enhanced product quality and material performance.
Experimental methods include tensile testing at various temperatures and deformation rates, as
well as microstructural analysis. The results provide insights into optimizing thermomechanical
processing regimes for better mechanical properties and efficiency in metal forming.
Key words:
Isothermal deformation, steel microstructure, mechanical properties, high-
temperature testing, thermomechanical processing, tensile testing, alloy deformation
To solve the assigned tasks, technically pure iron, A40G, U8A, and U12A steels were selected.
The choice of these materials is justified by the following reasons: firstly, they cover the entire
"steel" section of the iron-carbon phase diagram; secondly, these industrially produced materials
have a similar composition in terms of main alloying elements and differ primarily in their carbon
content (see Table 1.1), which allows for determining the influence of cementite content on the
plasticity of steels.
The materials used for the research were wires hot-rolled in the plastic state. The chemical
composition of the materials under investigation is presented in Table 2.1.
Table 1.1
Chemical Composition of the Materials Under Investigation
№
t/r
Steel grades
C
Mn
Si
S
P
Cu
1.
Technically pure iron
0,04
0,30
0,35
0,01-0,02
-
0,28
2.
Steel grade A40G
0,40
0,80
0,28
0,41
0,016
-
3.
Steel grade U8A
0,79
0,35
0.2
0,03
-
-
4.
Steel grade U12A
1.17
0,36
0,18
-
-
-
The microstructure of the steels in the initial sample state was studied in both the longitudinal
and cross-sections of the wires.
INTERNATIONAL MULTIDISCIPLINARY JOURNAL FOR
RESEARCH & DEVELOPMENT
SJIF 2019: 5.222 2020: 5.552 2021: 5.637 2022:5.479 2023:6.563 2024: 7,805
eISSN :2394-6334
https://www.ijmrd.in/index.php/imjrd Volume 12, issue 06 (2025)
115
The microstructure of the steels in the initial sample state is shown in Figures 1.1a, b, and c.
A40G steel has a ferrite–lamellar pearlite structure, U8A steel exhibits a eutectoid (0.8% carbon)
pearlitic structure in the initial state, while U12A steel has a eutectoid structure consisting of
pearlite and cementite.
To study the effect of the initial state on high-temperature plasticity, thermal treatment
(quenching followed by high-temperature tempering) and prior hot deformation were applied.
a) Commercially pure iron; b) A40G steel; c) U8A steel; d) U12A steel, 500× magnification
Figure 1.1. Microstructure of steels in the initial condition:
§ 2.2. Methodology of Mechanical Testing by Upsetting
Tensile tests at high temperatures
were carried out using a universal testing machine of the
brand
Instron
, model TT1114, within a temperature range of
400 to 1000 °C
and deformation
speeds ranging from
0.05 to 500 mm/min
. The samples were prepared according to
GOST 1495-
73
, with a gauge section diameter of
5 mm
and a length of
25 mm
. Heating of the samples to the
test temperatures was conducted in a
three-zone resistance furnace
, ensuring a temperature
deviation of no more than
±3 °C over a length of 300 mm
.
To ensure uniform heating and temperature stabilization
, the samples were held in the
furnace for
20 minutes prior to deformation
at the specified temperature.
INTERNATIONAL MULTIDISCIPLINARY JOURNAL FOR
RESEARCH & DEVELOPMENT
SJIF 2019: 5.222 2020: 5.552 2021: 5.637 2022:5.479 2023:6.563 2024: 7,805
eISSN :2394-6334
https://www.ijmrd.in/index.php/imjrd Volume 12, issue 06 (2025)
116
To reduce oxidation of the samples at high temperatures (t > 600–700 °C),
a protective
enamel coating such as
EVT13 or EVT24
was applied. This coating was rubbed onto the
working section of the sample
prior to heating
.
Two groups of samples were used in the experiments.
The
first group consisted of small
samples
with a
diameter of 10 mm and a height of 15 mm
. These samples were
deformed on a
U10 universal testing machine
with a strain (ε) ranging
from 30% to 80%
.
These samples were used in the development of a method for obtaining an ultrafine-
grained (UFG) structure,
with the aim of
systematically studying structural changes and
mechanical properties
during the process.
Preparation of Samples for Mechanical Testing
Another group of larger samples, with dimensions of 30 mm in diameter and 60 mm in height,
was subjected to isothermal upsetting in a die block using a modernized RN-100A hydraulic press
with a 100-ton capacity. Heating of the samples was carried out by an inductor connected to a
PST-100 converter. The deformation rate was
5·10⁻³ s⁻¹
, and the degree of deformation was at
least
60%
. From the large preforms (blanks) obtained after upsetting,
standard specimens
for
tensile mechanical testing (Figure 2.3) and
samples for microstructural investigations
were cut.
Figure 2.3.
Samples for upsetting, used for tensile mechanical testing and microstructural
investigations.
At each testing point, at least three samples were used. In this case, the
relative elongation (ẟ)
and the
yield strength (ẟ20)
were determined.
Based on the
force-time diagram
, the
uniformity of sample deformation
, and the
constancy of the volume of the deformable part of the sample
, the calculated cross-sectional
area was determined, and the
true yield stress
was obtained.
� =
�
�
INTERNATIONAL MULTIDISCIPLINARY JOURNAL FOR
RESEARCH & DEVELOPMENT
SJIF 2019: 5.222 2020: 5.552 2021: 5.637 2022:5.479 2023:6.563 2024: 7,805
eISSN :2394-6334
https://www.ijmrd.in/index.php/imjrd Volume 12, issue 06 (2025)
117
Here,
P
is the force acting on the sample at a given level of deformation, and
S
is the cross-
sectional area at the same deformation level.
Errors in measuring the yield stress mainly arise from the bending of curves due to stepwise
changes in strain rates, as well as from the method proposed by Bekofen [71]. Measuring
m
from
the bending of curves at a certain fixed level of strain is considered more reliable and convenient.
In determining mechanical properties, the diameters of the specimens were measured with a
micrometer to an accuracy of 0.01 mm, and the gauge length was measured with a caliper to an
accuracy of 0.05 mm. The scale of the elongation axis on the recording diagram was set at a ratio
of 10:1 relative to the strain rate. The plasticity of the specimens was evaluated based on the
maximum relative elongation (ẟ).
References
1. А.А.Бочвар, 3.А.Свидерская,. Явление сверхпластичности в цинк-алюминиевых
сплавах // Изв. АН СССР, ОТН, 1945. - № 9,- С. 821-824.
2. Строганов Г.Б., Кайбышев О.А., Фаткулин О.Х., Мартынов В.Н. Сверхпластичност и
износостойкост в машиностроении. «Алтекс». Москва, 2002 г. 320 с.
3. О.А. Кайбышев. Сверхпластичност промышленных сплавов. - M.: Металлургия, 1984. -
362 с.
4.
Matmurodov, F. M., Boboyev, X. X., Nugmanov, I. N., & Mamirov, S. S. (2023, September).
Analytical dynamic modeling of damping of a multi-hierarchical mechanical system and
mobile power engine shaft with the help of multi-mass rheological models. In
Journal of
Physics: Conference Series
(Vol. 2573, No. 1, p. 012044). IOP Publishing.
5. А
Matmurodov, F. M., Turapov, E. I., Abduvaliyev, U. A., Boboyev, X. X., Abdurakhmanova,
M. M., & Bakirov, F. A. (2023, March). Creating an innovative multi-operating wide-covered
universal frame with different replacement machine. In
American Institute of Physics
Conference Series
(Vol. 2612, No. 1, p. 050040).
6.
УА Абдувалиев, ШШЎ Мамиров, РТЎ Нуруллаев - Universum: технические науки,
2023
.
https://cyberleninka.ru/article/n/vliyanie-sherohovatosti-poverhnosti-shpindeley-na-
zazelenenie-i-stabilnost-raboty-hlopkouborochnogo-apparata
7.
U Abduvaliev, A Jumaev, R Nurullaev, A Ashirov… - International Conference on Reliable
Systems …, 2024
,
https://link.springer.com/chapter/10.1007/978-3-031-70670-7_25
8.
U Abduvaliev, A Jumaev, R Nurullaev, S Jakhonov… - E3S Web of Conferences, 2024
.
E3S
Web
of
Conferences,
conferences.org/articles/e3sconf/abs/2024/78/e3sconf_agritech-x_04013/e3sconf_agritech-
9.
Р.Т.
Нуруллаев.
Теоретико-экспериментальные
исследовния активности шпинделей. Материалы международной конференции.
Наманган 23-24 сентября 2022 г.
10.
Абдувалиев У.А., Мамиров Ш.Ш., Нуруллаев Р.Т.
ВЛИЯНИЕ ШЕРОХОВАТОСТИ ПОВЕРХНОСТИ ШПИНДЕЛЕЙ НА ЗАЗЕЛЕНЕНИЕ
И СТАБИЛЬНОСТЬ РАБОТЫ ХЛОПКОУБОРОЧНОГО АППАРАТА // Universum:
технические науки : электрон. научн. журн. 2023. 5(110). с.46-54
URL:
https://7universum.com/ru/tech/archive/item/15576
11.
Абдувалиев У.А., Нуруллаев Р.Т., Жахонов Ш.А., Влияние Физико-Механических
Свойств Хлопчатника И Рельефа Поля На Стабильность Работы Шпинделей
INTERNATIONAL MULTIDISCIPLINARY JOURNAL FOR
RESEARCH & DEVELOPMENT
SJIF 2019: 5.222 2020: 5.552 2021: 5.637 2022:5.479 2023:6.563 2024: 7,805
eISSN :2394-6334
https://www.ijmrd.in/index.php/imjrd Volume 12, issue 06 (2025)
118
Хлопкоуборочной
Машины.
Vol.
44
(2024):
Miasto
Przyszłości.
https://miastoprzyszlosci.com.pl/index.php/mp/article/view/2391
12.
Абдувалиев У.А., Нуруллаев Р.Т., Жахонов Ш.А., ACADEMIC INTERNATIONAL
CONFERENCE ON MULTI-DISCIPLINARY STUDIES AND EDUCATION. ВЛИЯНИЕ
ШЕРОХОВАТОСТИ ПОВЕРХНОСТИ МЕТАЛЛА НА КОЭФФИЦИЕНТ ТРЕНИЯ
ХЛОПКА-СЫРЦА ПРИ РАЗЛИЧНЫХ НОРМАЛЬНЫХ ДАВЛЕНИЯХ φ(N). С.69-73
https://aidlix.com/index.php/us/article/view/40
13. Абдувалиев У.А., Нуруллаев Р.Т., SHPINDEL SIRTIDAGI TISHLARNING
JOYLASHISHI ZICHLIGI VA BIR TEKISDALIGINI ANIQLASH.
МЕХАНИКА ВА
ТЕХНОЛОГИЯ ИЛМИЙ ЖУРНАЛИ, 2023, № 2 (11) С.46-54
