Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface
In this work, we studied the properties of samples from steel 15Cr12WNiMoV after vacuum activated chromium plating at temperatures of 1070 and 1100 °C for 4 and 10 h. It was found that after chemical-thermal treatment on the samples a diffusion layer with a thickness of 50 to 130 µm is formed, consi...
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2021
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| Cite this: | Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface / S.G. Rudenky, N.F. Kartzev, A.A. Korneev, A.V. Kunchenko, Y.V. Kunchenko, V.G. Marinin, L.I. Martynenko, V.I. Kovalenko, M.O. Bortnytska, T.P. Ryzhova, I.A. Lashenko, S.V. Gozhenko, Y.А. Krainyuk // Problems of Atomic Science and Technology. — 2021. — № 2. — С. 129-135. — Бібліогр.: 10 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1949612025-02-10T01:16:18Z Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface Властивості сталі 15Х12ВНМФ після вакуумного активованого хромування її поверхні Свойства стали 15Х12ВНМФ после вакуумного активированного хромирования ее поверхности Rudenky, S.G. Kartzev, N.F. Korneev, A.A. Kunchenko, A.V. Kunchenko, Y.V. Marinin, V.G. Martynenko, L.I. Kovalenko, V.I. Bortnytska, M.O. Ryzhova, T.P. Lashenko, I.A. Gozhenko, S.V. Krainyuk, Y.А. Physics of radiation and ion-plasma technologies In this work, we studied the properties of samples from steel 15Cr12WNiMoV after vacuum activated chromium plating at temperatures of 1070 and 1100 °C for 4 and 10 h. It was found that after chemical-thermal treatment on the samples a diffusion layer with a thickness of 50 to 130 µm is formed, consisting of 56…82 wt.% of chromium, the rest is iron. Metallographic studies were carried out on the samples and tests for heat resistance were carried out at a temperature of T = 900 °C. It was found that chrome-plated samples significantly exceed the initial samples and nitrided ones in terms of heat resistance. Tests of samples for tensile strength after chromium plating showed a significant increase in strength indicators for ultimate strength and yield strength. The plasticity characteristics of these samples are reduced. Проведені дослідження властивостей зразків зі сталі 15Х12ВНМФ після вакуумного активованого хромування при температурах 1070 і 1100 °С протягом 4 і 10 год. Установлено, що після хіміко-термічної обробки на зразках формується дифузійний шар товщиною від 50 до 130 мкм, що складається з 56…82 ваг.% хрому, інше – залізо. На зразках були проведені металографічні дослідження й здійснені випробування на жаростійкість при Т = 900 °С. Установлено, що хромовані зразки по жаростійкості значно перевершують вихідні зразки й азотовані. Проведені випробування зразків на міцність на розрив після хромування показали істотне збільшення міцностних показників для межі міцності й межі текучості. Характеристики пластичності цих зразків зменшуються. Проведены исследования свойств образцов из стали 15Х12ВНМФ после вакуумного активированного хромирования при температурах 1070 и 1100 °С в течение 4 и 10 ч. Установлено, что после химикотермической обработки на образцах формируется диффузионный слой толщиной от 50 до 130 мкм, состоящий из 56…82 вес.% хрома, остальное – железо. На образцах были проведены металлографические исследования и осуществлены испытания на жаростойкость при Т = 900 °С. Установлено, что хромированные образцы по жаростойкости значительно превосходят исходные образцы и азотированные. Проведенные испытания образцов на прочность на разрыв после хромирования показали существенное увеличение прочностных показателей для предела прочности и предела текучести. Характеристики пластичности этих образцов уменьшаются. 2021 Article Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface / S.G. Rudenky, N.F. Kartzev, A.A. Korneev, A.V. Kunchenko, Y.V. Kunchenko, V.G. Marinin, L.I. Martynenko, V.I. Kovalenko, M.O. Bortnytska, T.P. Ryzhova, I.A. Lashenko, S.V. Gozhenko, Y.А. Krainyuk // Problems of Atomic Science and Technology. — 2021. — № 2. — С. 129-135. — Бібліогр.: 10 назв. — англ. 1562-6016 DOI: https://doi.org/10.46813/2021-132-129 https://nasplib.isofts.kiev.ua/handle/123456789/194961 621.793.6:620.181.4 en Вопросы атомной науки и техники application/pdf Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Physics of radiation and ion-plasma technologies Physics of radiation and ion-plasma technologies |
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Physics of radiation and ion-plasma technologies Physics of radiation and ion-plasma technologies Rudenky, S.G. Kartzev, N.F. Korneev, A.A. Kunchenko, A.V. Kunchenko, Y.V. Marinin, V.G. Martynenko, L.I. Kovalenko, V.I. Bortnytska, M.O. Ryzhova, T.P. Lashenko, I.A. Gozhenko, S.V. Krainyuk, Y.А. Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface Вопросы атомной науки и техники |
| description |
In this work, we studied the properties of samples from steel 15Cr12WNiMoV after vacuum activated chromium plating at temperatures of 1070 and 1100 °C for 4 and 10 h. It was found that after chemical-thermal treatment on the samples a diffusion layer with a thickness of 50 to 130 µm is formed, consisting of 56…82 wt.% of chromium, the rest is iron. Metallographic studies were carried out on the samples and tests for heat resistance were carried out at a temperature of T = 900 °C. It was found that chrome-plated samples significantly exceed the initial samples and nitrided ones in terms of heat resistance. Tests of samples for tensile strength after chromium plating showed a significant increase in strength indicators for ultimate strength and yield strength. The plasticity characteristics of these samples are reduced. |
| format |
Article |
| author |
Rudenky, S.G. Kartzev, N.F. Korneev, A.A. Kunchenko, A.V. Kunchenko, Y.V. Marinin, V.G. Martynenko, L.I. Kovalenko, V.I. Bortnytska, M.O. Ryzhova, T.P. Lashenko, I.A. Gozhenko, S.V. Krainyuk, Y.А. |
| author_facet |
Rudenky, S.G. Kartzev, N.F. Korneev, A.A. Kunchenko, A.V. Kunchenko, Y.V. Marinin, V.G. Martynenko, L.I. Kovalenko, V.I. Bortnytska, M.O. Ryzhova, T.P. Lashenko, I.A. Gozhenko, S.V. Krainyuk, Y.А. |
| author_sort |
Rudenky, S.G. |
| title |
Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface |
| title_short |
Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface |
| title_full |
Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface |
| title_fullStr |
Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface |
| title_full_unstemmed |
Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface |
| title_sort |
properties of 15cr12wnimov steel after vacuum activated chromium plating of its surface |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2021 |
| topic_facet |
Physics of radiation and ion-plasma technologies |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/194961 |
| citation_txt |
Properties of 15Cr12WNiMoV steel after vacuum activated chromium plating of its surface / S.G. Rudenky, N.F. Kartzev, A.A. Korneev, A.V. Kunchenko, Y.V. Kunchenko, V.G. Marinin, L.I. Martynenko, V.I. Kovalenko, M.O. Bortnytska, T.P. Ryzhova, I.A. Lashenko, S.V. Gozhenko, Y.А. Krainyuk // Problems of Atomic Science and Technology. — 2021. — № 2. — С. 129-135. — Бібліогр.: 10 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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ISSN 1562-6016. PASТ. 2021. №2(132), p. 129-135.
https://doi.org/10.46813/2021-132-129
UDC 621.793.6:620.181.4
PROPERTIES OF 15Cr12WNiMoV STEEL AFTER VACUUM
ACTIVATED CHROMIUM PLATING OF ITS SURFACE
S.G. Rudenky, N.F. Kartzev, A.A. Korneev, A.V. Kunchenko, Y.V. Kunchenko,
V.G. Marinin, L.I. Martynenko, V.I.Kovalenko, M.O.Bortnytska, T.P. Ryzhova,
I.A. Lashenko, S.V. Gozhenko, Y.А. Krainyuk
National Science Center “Kharkov Institute of Physics and Technology”, Kharkiv, Ukraine
E-mail: martynenko@ kipt.kharkov.ua; tel. +38(057)335-63-98
In this work, we studied the properties of samples from steel 15Cr12WNiMoV after vacuum activated chromium
plating at temperatures of 1070 and 1100 °C for 4 and 10 h. It was found that after chemical-thermal treatment on
the samples a diffusion layer with a thickness of 50 to 130 µm is formed, consisting of 56…82 wt.% of chromium,
the rest is iron. Metallographic studies were carried out on the samples and tests for heat resistance were carried out
at a temperature of T = 900 °C. It was found that chrome-plated samples significantly exceed the initial samples and
nitrided ones in terms of heat resistance. Tests of samples for tensile strength after chromium plating showed a
significant increase in strength indicators for ultimate strength and yield strength. The plasticity characteristics of
these samples are reduced.
INTRODUCTION
The current state of the turbine industry requires
constant improvement of the materials used in this
industry. One of the ways to improve the characteristics
of materials is the use of protective coatings. Steel
15Cr12WNiMoV is widely used in industry, in
particular, in mechanical engineering. This steel grade is
used as a material for turbine parts manufactured at
public joint-stock company “Turboatom”. It is
impossible to predict which coating, as well as the
method of its formation, can positively affect the quality
of products from this steel grade. This requires practical
research.
Considering that steam turbine parts usually operate
under conditions of high temperatures and mechanical
destructive loads, it is necessary, first of all, to increase
the heat resistance of the product surface. One of the
elements that are heat-resistant and significantly
increase the corrosion resistance of alloys is chromium.
As shown by the data of numerous studies, starting with
the monograph [1], at present, research continues on
various methods of chromium plating and materials that
are processed [2–5]. We use the method of vacuum
activated diffusion saturation for chromium plating of
metal and alloy products [6, 7]. When this chemical-
thermal treatment is carried out in sodium chloride
vapor, an environmentally friendly process takes place.
Our earlier studies on the chromium plating of
samples from unalloyed steels of grade St.3, St.20, St.45
and U8 showed that when processing these materials, a
diffusion layer is formed, consisting of chromium
carbides Cr23C6, Cr7C3, and a solid solution of this
element in iron [8]. The process of formation of a
diffusion layer occurs through the formation of a
gaseous saturating medium consisting of lower
chromium chlorides.
In the case of diffusion chromium plating of the
surface of 25Cr1MoV steel, it leads to the formation of
a surface layer containing from 87 to 97 wt.% of this
element [9]. It was found that an increase in the
temperature of the process and its duration leads to an
increase in the chromium content on the surface of the
samples. The tests carried out on the effect of
cavitation-erosion and mechanical wear on the surface
of steel 25Cr1MoV show that chemical-thermal
treatment increases the resistance of this material. The
aim of this work is to study the characteristics of
15Kh12VNMF steel after vacuum activated chromium
plating of its surface. To establish the dependence of the
influence of the parameters of the chromium plating
process on the heat resistance and mechanical strength
of specimens from this steel.
MATERIALS AND RESEARCH METHODS
Round washers made of 15Cr12WNiMoV steel with
a diameter of 18 mm and a thickness of 4 mm were used
as samples for chrome plating and subsequent studies.
In the comparative tests, we used samples of
15Cr12WNiMoV steel, which had been furnace nitrided
at public joint-stock company “Turboatom”. These
samples were tested for resistance to cavitation using
the vibration method. The NSC KIPT developed a stand
for creating cavitation [10]. Abrasive mechanical wear
was investigated using an ABI-1 unit. The wear was
carried out according to the plane-disk scheme. The
speed of movement of the disk surface in contact with
the plane of the sample is 4.38 m/s, and the load on the
sample is 2.2 N. The wear rate was determined by
measuring the weight loss of the sample over a fixed
time. The chemical composition of the surface of the
samples was determined by X-ray fluorescence analysis
using an SPRUT device. The structural composition of
the chrome-plated surface was determined by X-ray
diffraction analysis using a DRON-3 device. The
structure of the samples after chemical-thermal
treatment was studied by metallographic analysis. Heat
resistance tests of the samples were carried out in air in
a muffle furnace. Mechanical tests were carried out on
an INSTRON-5581 electromechanical machine using a
strain gauge with a maximum load of 50 kN.
RESULTS AND ITS DISCUSSION
In this work, we investigated the surface
composition of 15Cr12WNiMoV steel after chemical
thermal treatment. Table 1 shows the results of
investigating the surface of 15Cr12WNiMoV steel after
its chemical-thermal treatment. The chemical
composition of the surface was determined by was
determined by X-ray fluorescence analysis.
Table 1
Chemical composition of the 15Cr12WNiMoV steel surface after chromium plating
Material Mass fraction of elements, wt.%
Steel
15H12VNMF
according to
state standard
C Si Mn Ni S P Cr Mo W V Ti Cu Fe
0.12-
0.18
<
0.40
0.50-
0.90
0.40-
0.80
<
0.025
<
0.03
11.0-
13.0
0.50-
0.70
0.70-
1.10
0.15-
0.30
Up
to
0.2
<
0.30
~83
Initial
steel – 0.8 0.9 0.5 – – 11.2 – 0.7 – – 0.5 85.4
Nitrided *
steel – 0.2 0.5 0.5 – – 9.9 0.7 – – – – 88.5
Chrome steel:
Т=1070
0
С,
6 h
– 0.1 – – – – 64.3 0.8 – – – – 34.7
chrome steel:
Т=1070
0
С,
10 h
– – – – – – 82.9 0.6 – – – 0.3 16.1
Chrome steel:
Т=1100
0
С,
4 h
– – – – – – 59 – – – – – 41
Chrome steel:
Т=1100
0
С,
10 h
– 0.3 – – – – 76 0.6 – – – – 23
*Samples had been furnace nitrided at public joint-stock company “Turboatom”.
The results presented in Table 1 show the results in
the storage of surfaces from steel 15X12VNMF, which
drastically changes the warehouse of surfaces. Alloying
additives present in the original steel according to state
standard practically disappear from the surface layer. As
follows from the results given in the table, the
chromium concentration in the surface layer changes
depending on the chromium plating temperature. During
vacuum chemical-thermal treatment, two parallel
processes take place – the precipitation of chromium in
the surface layer and its diffusion into the interior of the
steel. As a result, although with an increase in the
temperature of the process, there is an increase in the
release of chromium, but the rate of diffusion processes
also increases. This leads to a lower concentration of
chromium in the surface layer of the steel at a higher
temperature of the chemical heat treatment process.
Below are photographs of the microstructure of the
cross section of the samples after vacuum chromium
plating (Fig. 1).
On a special stand, comparative studies of the
samples for resistance to cavitation created using the
vibration method were carried out.
a b
Fig. 1. A photograph of a thin section of specimens made of steel 15Cr12WNiMoV,
which were chrome-plated: a – at a temperature of 1070
0
C, 4 h; b – at a temperature of 1070
0
C, 10 h.
Depending on the temperature of chemical-thermal treatment in the range of 1070…1100
0
C and its duration of
4…10 h, the thickness of the diffusion layer varies from 50 to 130 µm
The results of the incidence of abrasion and cavitation are given in Table 2.
Table 2
Wear of 15Cr12WNiMoV steel for abrasive and cavitation
Sample numbers
corresponding to curve numbers
1 2 3 4 5 6 7
Sample numbers during
processing
35 36 10 20-А1 20-А2 46 53
Processing
parameters
temperature
T, K
without
processing
furnace
nitriding
1343 1373 1373 1343 1373
time
t, ks
– – 14.4 14.4 21.6 36.0 36.0
Destruction
rate when
exposed to
abrasive
mg/ks 3.6 8.2 9.09 12.12 8.5 8.4 4.5
Destruction
rate when
exposed to
cavitation
m/ks 0.43 0.1 0.938 1.19 0.156 1.85 1.69
The curves shown in Fig. 2 allow expressing a
certain opinion. Kinetic curves 1, 2 have the same form,
while others differ depending on the parameters of the
chromium plating process. These are curves describing
the process of destruction of samples of the initial steel
and steel, which has passed the furnace nitriding at the
enterprise. The remaining curves 3–7 describe the
destruction of samples that have undergone vacuum-
activated chromium plating. As follows from the data in
Table 1, the surface layer having a high chromium
concentration is inferior in resistance to the original
steel.
Table 2 shows the results of wear of steel samples
from cavitation and abrasive. In this table, samples 1
and 2 are respectively original and nitrided. These
samples are superior in resistance to cavitation and
abrasion wear of all samples that have undergone
vacuum chrome plating. Chromium plating of samples
changes their resistance to cavitation and abrasives,
while the rate of destruction depends on the process
parameters (temperature and time). Therefore, it may be
necessary to select the parameters of the chromium
plating regime in order to preserve the resistance of the
samples when exposed to cavitation and abrasive wear.
Investigations were carried out on the effect of
vacuum activated diffusion chromium plating of the
surface of 15Cr12WNiMoV steel on the heat resistance
of this material. Comparative tests were carried out in
air at temperatures of 700, 900, and 1100
0
C. In these
tests, the initial sample, nitrided, and the samples,
chrome-plated with different processing parameters,
were simultaneously placed in a ceramic boat. Table 3
below shows the results of tests for heat resistance at a
temperature of T = 900
0
C.
Fig. 2. Kinetic curves of cutting of steel 15Cr12WNiMoV at
the stage of cavitation: 1 – without processing; 2 – food for
food nitrogen; 3 – 7 – chrome wash at low temperatures
and hour: 3 – T = 1343 K, t = 14.4 ks;
4 – T = 1373 K, t = 14.4 ks; 5 – T = 1373 K, t = 21.6 ks;
6 – T = 1343 K, t = 36.0 ks; 7 – T = 1373 K, t = 36.0 ks
Table 3
Tests of specimens from steel 15Cr12WNiMoV for heat resistance in air at temperature T = 900
0
C,
total duration 15.5 h
No Material, processing Sample weight, g
Change in sample
weight, g
Total change in
sample weight, g
1 Steel 15Cr12WNiMoV,
initial steel
Р0=4.50705 0.04995*
Р7=4.50965 ∆Р1=0.0026
Р5.5=4.54700 ∆Р2=0.03735
Р3=4.51160 ∆Р3= - 0.03540
2 Steel 15Cr12WNiMoV,
nitrided steel
Р0=4.45360 0.09700*
Р7=4.49965 ∆Р1=0.04605
Р5.5=4.55060 ∆Р2=0.05095
Р3=4.40180 ∆Р3= -0.14880
3 Steel 15Cr12WNiMoV,
chrome steel:
Т=1070
0
С, 4 h
Р0=4.51880 0.00085
Р3.5=4.51910 ∆Р1=0.00030
Р3.5=4.51960 ∆Р2=0.00050
Р4.5=4.51965 ∆Р3=0.00005
4 Steel 15Cr12WNiMoV,
chrome steel:
Т=1070
0
С, 10 h
Р0=4.56900 0.00055
Р3.5=4.56920 ∆Р1=0.00020
Р3.5=4.56935 ∆Р2=0.00015
Р4.5=4.56940 ∆Р3=0.00005
Р4=4.56955 ∆Р4=0.00005
5 Steel 15Cr12WNiMoV,
chrome steel:
Т=1100
0
С, 4 h
Р0=4.54020 0.00145
Р3.5=4.54085 ∆Р1=0.00065
Р3.5=4.54145 ∆Р2=0.00060
Р4.5=4.54165 ∆Р3=0.00020
6 Steel 15Cr12WNiMoV,
chrome steel:
Т=1100
0
С, 10 h
Р0=4.60030 0.00018
Р3.5=4.60055 ∆Р1=0.00015
Р3.5=4.60080 ∆Р2=0.00025
Р4.5=4.60100 ∆Р3=0.00020
Р4=4.600120 ∆Р4=0.00020
*In these cases, the total weight change was reported in 12.5 h.
In the Table in the third capital, Pτ is the weight of the sample, where τ is the time of testing.
Based on the data presented in Table 3, certain
conclusions can be drawn. The change in weight for the
original samples is about 0.5 g, and the nitrided samples
have changed in weight by half. The change in weight
of chrome-plated samples is much less - it ranges from
0.0002 to 0.00145g. This means that the heat resistance
of chrome-plated specimens is much higher than that of
the original specimens and those that have undergone
nitriding.
Tests of samples made of 15Cr12WNiMoV steel for
rupture and bending were carried out.
The results presented in Table 4 show that the initial
samples have satisfactory characteristics in comparison
with the data for this steel given in according to state
standard 19442-74. More precisely, the average value of
the conventional yield stress for the initial samples is
approximately at the same level. The average tensile
strength of the metal of the original samples exceeds the
values given in according to state standard 19442-74 for
this steel by about 130 MPa and reaches 864 MPa. With
respect to elongation (δ, %) for the steel of the initial
samples, it is close to the values of according to state
standard 19442-74. However, the relative narrowing
(ψ, %) has a higher value by 5…10%.
The obtained data for nitrided specimens in terms of
strength characteristics are comparable with the value
for the original specimens. According to the average
value, the yield stress for nitrided samples is lower by
about 70 MPa and is equal to about 623 MPa. At the
same time, the ultimate strength remains approximately
at the same level as the original samples – 823 MPa.
The plasticity characteristics of nitrided samples
compared with the original ones are 2 – 3 times less for
(δ, %) and 3 – 3.5 times for (ψ, %). During the tests, all
nitrided samples collapsed without necking, which
indicates the absence of significant deformation at the
fracture site. The plane of destruction has two zones: the
core and the outer circle. Probably, this can be
associated with the process of chemical-thermal
treatment of the metal.
Table 4
Tensile strength test of 15Cr12WNiMoV steel specimens at room temperature
Series Processing
No.
sample
Label
on ample
σ0.2,
MPa
σв,
MPa
δ, % Ψ, %
ТР17-565 Original 1 1 709 800 13.2 61
2 2 682 807 12.5 58
3 3 701 831 13.3 54
average 697 813 13 58
Nitrided 4 1 616 806 4.2 14,4
5 2 613 809 4.6 14,4
6 3 640 853 5.0 14,4
average 623 823 4.6 14.4
Chrome steel:
Т=1100
0
С, 4 h
7 1 848 1117 6.4 47
8 2 859 1135 7.6 47
9 3 822 1112 7.4 47
average 843 1121 7.1 47
Chrome steel:
Т=1100
0
С, 10 h
10 1 849 1147 10.0 54
11 2 876 1198 11.1 48
12 3 875 1116 6.1 52
average 867 1154 9.1 51
ТР17-
565
**
Original 1 1 712 832 12.0 61
2 2 721 833 10.9 58
3 3 734 858 12.6 60
average 722 841 11.8 60
Chrome steel:
Т=1070
0
С, 4 h
4 1 897 1206 7.9 44
5 2 910 1185 6.2 45
6 3 900 1199 7.6 45
average 902 1197 7.2 45
Chrome steel:
Т=1070
0
С, 10 h
7 1 800 1042 9.0 53
8 2 808 1066 10.2 53
9 3 790 945 6.4 54
average 799 1018 8.5 53
For specimens with different modes of diffusion
metallization with chromium in comparison with the
original specimens, there is a significant increase in
strength indicators by about 100…280 MPa for ultimate
strength and by about 60…200 MPa for yield strength.
The plasticity characteristics (δ, % and ψ, %) for
chrome-plated samples are lower than those for the
original ones. This is due to the hardening due to the
chromium plating of the steel and the high strength
values. Fracture of chromium-plated specimens
occurred with localization of deformation and necking.
The fracture surface has an uneven matte dark gray
appearance, sometimes it has the shape of a cup
fracture, which indicates a viscous nature of fracture.
Table 5
Bending test of specimens made of 15Cr12WNiMoV steel at room temperature
Sample condition σmax, MPa Bend angle, degrees Post-test condition
Original 1312 ≈ 90 Without cracks, overheads
Nitrided 1226 ≈ 30
Numerous small cracks
on the extended side
Chrome steel:
Т=1070
0
С, 4 h
1849 ≈ 90 Rib tear
Chrome steel:
Т=1070
0
С, 10 h
1164 ≈ 30
Crack 1/2 thickness
sample
Chrome steel:
Т=1100
0
С, 4 h
1772 ≈ 45 small tears
Chrome steel:
Т=1100
0
С, 10 h
1155 ≈ 30
Crack 1/2 thickness
sample
The results of bending tests of specimens made of
15Cr12WNiMoV steel presented in Table 5 at room
temperature showed the following. The surface of the
original specimen, stretched during the tests, remained
intact, without the appearance of tears and upon
deformation of the original specimens at an angle of
90 degrees without the appearance of cracks. The
maximum stress at an angle of 90 degrees reached an
average of 1312 MPa.
When testing nitrided samples, when the stress
reached 800…900 MPa, numerous small cracks began
to appear in the direction of the mandrel. The maximum
stress that the nitrided samples withstood on average
reached 1226 MPa. During the tests, under the action of
the load of the sample by the mandrel, deformation
(embrittlement) of the surface layer from the inner
radius (under the mandrel) occurred. The bending angle
at the specified load reached approximately 30 degrees.
Tests of samples chrome-plated for 4 h at a
temperature of T = 1070
0
C showed the following:
when the bending angle approaches 90 degrees,
distortion (deformation) of the metal occurred on the
lateral and external surfaces and a tear appeared on the
external (stretching) edge of the sample. The maximum
average stress that the samples withstood before the
appearance of a rupture is 1849 MPa.
Specimens, which were chromium-plated at a
temperature of T = 1070
0
C for 10 h, failed after
reaching stresses on average 1164 MPa. The bending
angle was no more than 30 degrees. Cracks developed
rapidly to almost ½ the thickness of the sample. On the
surface of the fracture, a silvery component with a
metallic luster prevails – brittle fracture.
Tests carried out on specimens that have undergone
chromium plating at T = 1100
0
C for 4 h have shown
that cracks appear when the bending angle becomes
close to 45 degrees. In this case, the maximum stress
averaged 1772 MPa. Before the appearance of small
tears on the lateral and external surfaces of the samples,
a slight bending of the metal occurred – the localization
of deformation, along which the crack began to develop.
At the bottom of the samples, I found the presence of a
viscous component on the fracture surface of the
samples, which indicates the occurrence of plastic
deformation processes in the bulk of the samples during
testing.
Samples that were chrome plated at 1100
0
C for 10 h
behaved as follows. During the tests, upon reaching an
angle of about 30 degrees and an average stress of
1155 MPa, a rapid growth of a crack from the outer
surface to half of the specimen thickness occurred. The
fracture has a silvery metallic luster, indicating brittle
fracture.
CONCLUSIONS
1. It was found that when chrome plating of
15Cr12WNiMoV steel samples, a diffusion layer with a
thickness of 50 to 130 μm is formed on them, depending
on the conditions of chemical-thermal treatment.
2. It was found that after vacuum activated
chromium plating, the chromium content in the surface
layer of steel 15Cr12WNiMoV varies within
56…82 wt.%, the rest is iron.
3. Tests of samples made of 15Cr12WNiMoV steel
for abrasive wear and cavitation showed that after
saturation of the steel surface with chromium, its
resistance is somewhat inferior to the original material.
4. Comparative tests for heat resistance in air of
chrome-plated specimens of steel 15Cr12WNiMoV at a
temperature of T = 900
0
C were carried out. It has been
established that the heat resistance of chrome-plated
specimens is much higher than that of both the original
specimens and those that have undergone furnace
nitriding.
5. When testing samples with different modes of
diffusion metallization with chromium in comparison
with the original samples, a significant increase in
strength indicators for ultimate strength and yield
strength is noted. The plasticity characteristics for
specimens that have undergone chromium plating are
lower than those of the original ones.
6. Bending tests of 15Cr12WNiMoV steel
specimens at room temperature showed that specimens
that have undergone vacuum activated chromium
plating are less able to withstand such loads.
REFERENCES
1. G.N. Dubinin. Diffusion chromium plating of
alloys. M.: “Mechanical Engineering”, 1964, 451 p.
2. A.R. Castle, D.R. Gabe Chromium diffusion
coatings // International Materials Reviews. 1999, v. 44,
N 2, p. 37-58.
3. R. Bianco, M.A. Rapp. Codeposition of Elements
in Diffusion Coatings by the Halide-Activated Pack
Cementation Method // Journal of Metals. 1991, p. 68-
73.
4. A.M. Guryev, B.D. Lygdenov, S.P. Ivanov, et al.
New methods of diffusion thermocyclic hardening of
the surface of steel products with boron together with
titanium and chromium // Fundamental research. 2007.
N 10, p. 89-91.
5. S.G. Rudenkiy. Vacuum-activated chromium
plating of steel 20 in nanocrystalline powder // Physical
surface engineering, 2012, v. 10, N 1, p. 29-35.
6. Method of diffusion saturation of product surface
/ V.I. Serpent, M. Kartmazov, S. Rudenkiy. Patent for
invention No. 98074, С23С 8/00, С23С 12/00Publ.
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Patent for invention No. 98087, С23С 8/00, С23С
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Article received 25.03.2021
СВОЙСТВА СТАЛИ 15Х12ВНМФ ПОСЛЕ ВАКУУМНОГО
АКТИВИРОВАННОГО ХРОМИРОВАНИЯ ЕЕ ПОВЕРХНОСТИ
С.Г. Руденький, Н.Ф. Карцев, А.А. Корнеев, А.В. Кунченко, Ю.В. Кунченко, В.Г. Маринин,
Л.И. Мартыненко, В.И. Коваленко, М.А. Бортницкая, Т.П. Рыжова, И.А. Ляшенко,
С.В. Гоженко, Е.А. Крайнюк
Проведены исследования свойств образцов из стали 15Х12ВНМФ после вакуумного активированного
хромирования при температурах 1070 и 1100 °С в течение 4 и 10 ч. Установлено, что после химико-
термической обработки на образцах формируется диффузионный слой толщиной от 50 до 130 мкм,
состоящий из 56…82 вес.% хрома, остальное – железо. На образцах были проведены металлографические
исследования и осуществлены испытания на жаростойкость при Т = 900 °С. Установлено, что
хромированные образцы по жаростойкости значительно превосходят исходные образцы и азотированные.
Проведенные испытания образцов на прочность на разрыв после хромирования показали существенное
увеличение прочностных показателей для предела прочности и предела текучести. Характеристики
пластичности этих образцов уменьшаются.
ВЛАСТИВОСТІ СТАЛІ 15Х12ВНМФ ПІСЛЯ ВАКУУМНОГО АКТИВОВАНОГО
ХРОМУВАННЯ ЇЇ ПОВЕРХНІ
С.Г. Руденький, М.Ф. Карцев, О.О. Корнєєв, О.В. Кунченко, Ю.В. Кунченко, В.Г. Маринін,
Л.І. Мартиненко, В.І. Коваленко, М.О. Бортницька, Т.П. Рижова, І.А. Ляшенко,
С.В. Гоженко, Є.О. Крайнюк
Проведені дослідження властивостей зразків зі сталі 15Х12ВНМФ після вакуумного активованого
хромування при температурах 1070 і 1100 °С протягом 4 і 10 год. Установлено, що після хіміко-термічної
обробки на зразках формується дифузійний шар товщиною від 50 до 130 мкм, що складається з
56…82 ваг.% хрому, інше – залізо. На зразках були проведені металографічні дослідження й здійснені
випробування на жаростійкість при Т = 900 °С. Установлено, що хромовані зразки по жаростійкості значно
перевершують вихідні зразки й азотовані. Проведені випробування зразків на міцність на розрив після
хромування показали істотне збільшення міцностних показників для межі міцності й межі текучості.
Характеристики пластичності цих зразків зменшуються.
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