Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading
It has been determined by Auger-analysis method, roentgenofluorescence method, and the diffraction analysis that dark spots which appear in the examined steel under cyclic loading are new phases. У статті представлені результати отримані за допомогою оже-електронної спектроскопії (AES), дифракція ре...
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Науковий фізико-технологічний центр МОН та НАН України
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| Cite this: | Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading / L.A. Gorbachyov, A.D. Pogrebnjak // Физическая инженерия поверхности. — 2009. — Т. 7, № 1-2. — С. 23-27. — Бібліогр.: 9 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859721719566041088 |
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| author | Gorbachyov, L.A. Pogrebnjak, A.D. |
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| citation_txt | Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading / L.A. Gorbachyov, A.D. Pogrebnjak // Физическая инженерия поверхности. — 2009. — Т. 7, № 1-2. — С. 23-27. — Бібліогр.: 9 назв. — англ. |
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| description | It has been determined by Auger-analysis method, roentgenofluorescence method, and the diffraction analysis that dark spots which appear in the examined steel under cyclic loading are new phases.
У статті представлені результати отримані за допомогою оже-електронної спектроскопії (AES), дифракція рентгенівських променів (XRD), атомно-силової мікроскопії (AFM), рентгенофлюоресцентного аналізу, растрової і оптичної мікроскопії по дослідженню зразків СТ 3. Після циклічного навантаження показаний зв’язок між втомними характеристиками і физико-хімічними і механічними властивостями.
В статье представлены результаты полученные с помощью оже-электронной спектроскопии (AES), дифракция рентгеновских лучей (XRD), атомно-силовой микроскопии (AFM), рентгенофлюоресцентного анализа, растровой и оптической микроскопии по исследованию образцов СТ 3. После циклической нагрузки показана связь между усталостными характеристиками и физико-химическими и механическими свойствами.
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ФІП ФИП PSE, 2009, т. 7, № 1-2, vol. 7, No. 1-2 23
Dark spots appear in the microstructures of some
balanced condition metals (carbon steels, copper,
polycrystals of lead [1] and others) when they
are exposed to cyclic loading. At the initial stage,
they appear as separate small darkenings, which
can further spread over all metal grains and cover
a considerable part of the deformed area,
especially when it is close to metal failure.
Fig. 1 shows the temperature kinetic fatigue
curve with the points of observation and the mic-
rostructure corresponding to these points; dashed
lines and Roman figures show the devision into
failure time stages.
In our paper [2] we suggested distinguishing
the following stages of the fatigue failure process:
1. Incubatory stage.
2. The stage of slip bands active formation.
3. The stage of local accumulation of damage
and changes which occurred during the first and
the second phases.
4. The main crack propagation and growth stage.
5. The sample failure stage. The duration of this
stage for light section samples is insignificant.
As it can be seen in fig. 1, when the stage of
slip bands active formation is over (point of ob-
servation 2), no new slip bands appear, but the
dark spots prominence and density gradually
increase and peak at the end of the third stage
(point of observation 3). This fact can indicate
the final depletion of the sample ductility reserve
in the deformed area and its transition to a brittle
failure stage.
A lot of research of this phenomenon has been
done, for example [3], but the causes and the
nature of these spots are not clear yet.
Earlier in [4] we suggested a presumable in-
terpretation of these spots appearance and pro-
pagation causes.
First, these are the “weakest” grains and their
areas. Under the unfavourable conditions of a
flow shear they experience the primary impact
of high cyclic loading of the same sign – com-
pression – which causes their active cyclic defor-
mation. These spots prominence can indicate
pressing out considerable amounts of metal.
Second, the active repeated cyclic compres-
sion strain in these amounts of metal causes their
intensive heating which promotes these micro-
scopic volumes active oxidation. This process
can have a complex and specific nature due to
the cycling of loading and its frequency.
These spots are likely to have the same nature
as the aeration along the slip bands. They inten-
sively appear on rimmed steel which features
high ductility and gas content. Therefore, the in-
tensity of these spots can be related to the gas
content of the material itself. The more so, as
these spots appear when similar materials are
tested in vacuum [5].
In this paper we analyze the microstructure
of lamellar samples of low-carbon steel of the
content C = 0.05 – 0.12%; Mn = 0.25 – 50%;
STUDY OF STRUCTURE AND PHYSICO-CHEMICAL AND MECHANICAL
PROPERTIES IN LOW-CARBON STEEL AFTER CYCLIC LOADING
L.A. Gorbachyov*, A.D. Pogrebnjak**
*East Kazakhstan State Technical University (Ust-Kamenogorsk)
Kazakhstan
*Sumy Institute for Surface Modification
Ukraine
Received 26.02.2009
It has been determined by Auger-analysis method, roentgenofluorescence method, and the diffraction
analysis that dark spots which appear in the examined steel under cyclic loading are new phases.
Fig. 1. The kinetic fatigue curve and the photos of micro-
structures corresponding to observation points 1, 2, 3 on
the curve.
1
32
ФІП ФИП PSE, 2009, т. 7, № 1-2, vol. 7, No. 1-224
STUDY OF STRUCTURE AND PHYSICO-CHEMICAL AND MECHANICAL PROPERTIES IN LOW-CARBON STEEL AFTER CYCLIC LOADING
Si = 0.03% of 1×10 mm effective section under
the cyclic loading of alternating bending with
the frequency of cycling equal to 2800 cycle per
minute at the installation with the permanent total
amplitude [6].
SURFACE ALTERATIONS
EXAMINATION
To analyse the profile we got a 3-D image of the
sample’s initial and cyclically deformed areas
surfaces. Fig. 2 shows the profilograms of the
sample’s initial area (left) and its deformed area
(right).
Fig. 2 shows how significant the surface
alterations are under the cyclic loading. A special
attention should be given to the amount of the
deformed metal pressing out.
Auger-spectrogram. Fig. 3 shows Auger-
spectrogram results as graphs of component
depth concentration of the initial sample and of
the deformed one.
The contrastive analysis of these graphs shows
that after the strain cycling some radical changes
took place: the levels of carbon and ferrum con-
centration seem to have changed over. The level
of carbon concentration on the deformed sample
surface corresponds to the level of ferrum con-
centration on the initial sample surface, and the
level of ferrum concentration corresponds to the
level of carbon concentration on the initial
sample.
This must mean that as a result of diffusion
processes carbon shifted to a more heated near-
surface layer, where it could react with the alloy
components – oxygen and ferrum.
Fig. 4 shows the results of the initial and the
deformed samples surface scanning with a
1 mcm diameter scanning beam and the scanning
areas.
On the basis of the data show in fig. 4 we can
conclude that:
– the carbon and the ferrum graphs are
absolutely symmetrical (mirrored) which can
indicate their clear chemical interaction;
– Oxygen has also become active in the
deformed sample, at that the maximum peaks
of the ferrum and the carbon graphs
correspond to the oxygen activity spikes;
– as the scanning beam approaches the fatigue
crack with the maximum deformation value,
the divergence between the ferrum graph and
the carbon graph increases;
– all these give us reasons to conclude that
complex physical and chemical processes
with the possible formation of new
compounds occur in metals under cyclic
loading.
Fig. 5 shows Auger-spectra of the initial and
the deformed samples surfaces. Comparing these
Fig. 2. Three-dimensional AFM images of the initial
sample surface (1) and the deformed sample surface (2).
Fig. 3. AES-depth profiles of elements of samples.
L.A. GORBACHYOV, A.D. POGREBNJAK
ФІП ФИП PSE, 2009, т. 7, № 1-2, vol. 7, No. 1-2 25
spectra we can conclude that the range of carbon
and oxygen Auger lines in the deformed sample
has increased. That demonstrates and proves a
higher content of these elements compared to the
initial sample.
Exact measurement of the ferrum Auger line
showed that, though insignificantly, but none the
less it has slightly decreased, and it shows the
reduction of its concentration in the deformed
sample’s near-surface area.
If a part of ferrum atoms have supposedly
reacted with the oxygen and carbon atoms, then
such a reduction will be insignificant as the
carbon content in the examined steel does not
exceed 0.08 %, and the oxygen content is even
less. All the more so, as fig. 1 shows, the spots are
only located over an insignificant part of the
deformed area.
The results of roentgenofluorescence method
examination. One of the roentgenofluorescence
method parameters is the detection of companion
emission lines intensity ratio [7].
The method makes it possible to determine
the form of atoms in a solid body by the ratio of
integral intensity Кβ of X-ray spectrum lines to
integral intensity Кα.
Fig. 6 shows measured energy spectra and
calculated ratios Fe Кα1,2/Fe Кβ1,2.
We got the following results: this ratio for the
initial sample equals 7.0677624 ± 0.0005, and
for the deformed sample it equals 7.025773 ±
0.0005. The difference between the results ex-
ceeds measuring inaccuracy and shows the chan-
ge in the ferrum atoms chemical state (valency)
in the deformed sample. It means that physical
and chemical interaction between ferrum and the
sample material components takes place under
cyclic deformation. The insignificant divergence
between the peaks for the deformed sample (a
dashed line in fig. 6) and the initial sample is
explained by the incommensurability of the fer-
rum content concentration and all other compo-
nents – carbon and oxygen.
X-ray diffraction analysis results. To clarify
the foregoing results we carried out an X-ray dif-
fraction analysis of the initial and the deformed
surfaces. The analysis was carried out at a diffrac-
tometer Dron-3. We analyzed three samples in
different modes with chrome and cobalt-Кα emit-
ters.
Fig. 7 shows diffractograms of the deformed
sample (the upper diffractogram) and the initial
sample areas.
The diffractogram analysis revealed that:
– the intensity of α-Fe (200) line has decrea-
sed by the factor of 2 in the deformed areas in all
three samples, and the intensity of α-Fe (211)
Fig. 4. AES-depth profiles of the initial sample surface
(on the left) and the deformed sample surface (on the right).
Fig. 5. Auger-spectra of the initial (on the left) and the
deformed (on the right) samples surfaces.
Fig. 6. Energy spectra of the deformed and the initial
samples.
L.A. GORBACHYOV, A.D. POGREBNJAK
ФІП ФИП PSE, 2009, т. 7, № 1-2, vol. 7, No. 1-226
STUDY OF STRUCTURE AND PHYSICO-CHEMICAL AND MECHANICAL PROPERTIES IN LOW-CARBON STEEL AFTER CYCLIC LOADING
line has increased by the factor of 1.2, which can
be explained by the occurrence of texture (speci-
fic orientation of crystals);
– some weak lines appeared in the cyclically
deformed surface diffractograms besides
intensive α-Fe lines. These lines are marked “x”
in fig. 7. Their number is different in different
samples, which can be explained, as the spots
are located differently in each of the analyzed
samples. The number of these lines depends on
how many spots are in the analyzing beam focus.
The phase analysis of these lines showed that
C2FeO4 (iron oxalate) compounds are the most
suitable by interplanar distances.
To clarify the results that we got at Dron-3
diffractometer, we carried out the specifying exa-
mination at Х’ Pert PRO PANalytical diffracto-
meter (Holland) which confirmed the results that
we had got at Dron-3 diffractometer and detected
compounds C2FeO4 (iron oxalate) and FeCO3
(iron carbonate).
To evaluate the mechanical properties of the
revealed phases we measured nanohardness at
NHN – S – AX – 000X nanohardness meter.
The research results showed that the revealed
phases have hardness which is about twice as
little as the initial grain hardness (Hv 163 and
303 correspondingly), they are probably incohe-
rent fine-dispersed mixture of the above-men-
tioned compounds. When an indenter enters this
phase, there appears a horizontal line in the “load
– indenter depth” graph.
Pursuant to the foregoing results, new phases
can occur in consequence of complex physical
and chemical processes under cyclic loading.
But it is known that the formation of such
compounds requires high temperature, while the
heating of the sample strained area under given
conditions (loading frequency of 2800 cycles
per minute) didn’t exceed 1.5 °С in relation to
the temperature of the environment.
The impact of the temperature on the fatigue
testing results is well-known; nevertheless, ther-
mal effects which occur in the material under
the cyclic load haven’t been studied enough.
The look of temperature kinetic fatigue curves
depends on the crystal lattice type.
Fig. 8 shows temperature kinetic fatigue
curves for different materials [8]. As it can be
seen, temperature kinetic curves for facecente-
red cubic lattice metals mirror temperature kine-
tic curves for body-centered cubic lattice metals.
We should mention that curves which indi-
rectly describe the fatigue process (temperature
curve, internal friction curve, mechanical hyste-
resis loop curve, etc.) have qualitatively identical
character.
The role of thermal processes at cyclic loads
can be illustrated with the following example.
Fig. 9 shows the fatigue testing results of in-
ternal friction changes in steel 50 samples with
and without cooling, other conditions being equal
[9].
The comparative analysis of the curves shows
that under normal conditions – without cooling
– the kinetic curve has a look peculiar for body-
centered cubic lattice metals, and with cooling
it looks like a curve for face-centered cubic lat-
tice metals. It can be assumed that this example
is a convincing evidence how inner thermal pro-
cesses impact the fatigue process. As for the for-
mation of the new phases that we explore in this
paper, their formation can be caused by thermal
fluctuations.
Fig. 7. X-ray diffraction pattern deformed samples (1)
and the initial samples (the lower one).
Fig. 8. Kinetic curves for different materials.
ФІП ФИП PSE, 2009, т. 7, № 1-2, vol. 7, No. 1-2 27
CONCLUSION
As is evident from the foregoing, we can state
that the dark spot-formations in the examined
steel microstructure are new phases.
REFERENCES
1. Panin V.E., Elsukova T.F., Panin A.V., Kuzi-
na O.Yu., Kuznetsov P.V.//Physical Mesomecha-
nics. – 2004. – Vol. 7, № 2. – P. 5-17.
2. Gorbachyov L.A., Lebedev T.A., Marinets T.K.
On Fatigue Failure Process Periods//A Journal
of Applied Mechanics and Technical Physics. –
1970. – № 5. – P. 133-136.
3. Guryev A.V., Stolyarov G.Yu. The formation of
fatigue striations on a Steel Surface//The USSR
Academy of Sciences Izvestiya Metals. – 1967.
– № 3. – P. 133-136.
4. Gorbachyov L.A. The Research of the Tempe-
rature Fatigue Failure Kinetics//Synopsis of a
Candidate of Science Thesis L. – 1971. – P. 18.
Fig. 9. Kinetic fatigue curves for steel 50 samples.
5. Lozinski M.G. The Application of High-Tem-
perature Metallography Method in the Research
of Metal and Alloy Structural Change Regularity
in the Process of Their Fatigue Testing//Collec-
tion of papers: Durability of Metals under Cyclic
Loading. М.: Nauka. – 1967. – p. 44-55.
6. Gorbachyov L.A., Lebedev T.A., Marinets T.K.
The Research of the Temperature Fatigue Failure
Kinetics//Collection of papers from Lening-
rad Polytechnical Institute. – 1970. – № 314. –
P. 128-133.
7. Verigin A.A. Energy-Dispersive X-Ray Spectro-
metry Analysis and its Industrial Use. Mono-
graph. – Tomsk: ТоmGU, 2005. – 241 p.
8. Gorbachyov L.A. On the Fatigue Equation for
the Stationary Mode of Loading//Zavodskaya La-
boratoriya. – 1972. – № 12. – P.1500-1503.
9. Kharitonov N.I., Nikolski N.N., Dronov V.S. The
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Cyclic Loading// Problems of durability. – 1972.
– № 9. – P. 44-48.
ВИВЧЕННЯ СТРУКТУРИ
ФІЗИКО-ХІМІЧНИХ І МЕХАНІЧНИХ
ВЛАСТИВОСТЕЙ МАЛОВУГЛЕЦЕВОЇ
СТАЛІ ПІСЛЯ ЦИКЛІЧНОГО
НАВАНТАЖЕННЯ
Л.А. Горбачов, О.Д. Погребняк
У статті представлені результати отримані за до-
помогою оже-електронної спектроскопії (AES),
дифракція рентгенівських променів (XRD),
атомно-силової мікроскопії (AFM), рентгено-
флюоресцентного аналізу, растрової і оптичної
мікроскопії по дослідженню зразків СТ 3. Після
циклічного навантаження показаний зв’язок між
втомними характеристиками і физико-хімічними
і механічними властивостями.
ИЗУЧЕНИЕ СТРУКТУРЫ
ФИЗИКО-ХИМИЧЕСКИХ И
МЕХАНИЧЕСКИХ СВОЙСТВ
МАЛОУГЛЕРОДИСТОЙ СТАЛИ ПОСЛЕ
ЦИКЛИЧЕСКОЙ НАГРУЗКИ
Л.А. Горбачев, А.Д. Погребняк
В статье представлены результаты полученные
с помощью оже-электронной спектроскопии
(AES), дифракция рентгеновских лучей (XRD),
атомно-силовой микроскопии (AFM), рентгено-
флюоресцентного анализа, растровой и опти-
ческой микроскопии по исследованию образцов
СТ 3. После циклической нагрузки показана
связь между усталостными характеристиками и
физико-химическими и механическими свойст-
вами.
L.A. GORBACHYOV, A.D. POGREBNJAK
|
| id | nasplib_isofts_kiev_ua-123456789-7945 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1999-8074 |
| language | English |
| last_indexed | 2025-12-01T09:55:38Z |
| publishDate | 2009 |
| publisher | Науковий фізико-технологічний центр МОН та НАН України |
| record_format | dspace |
| spelling | Gorbachyov, L.A. Pogrebnjak, A.D. 2010-04-22T14:23:05Z 2010-04-22T14:23:05Z 2009 Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading / L.A. Gorbachyov, A.D. Pogrebnjak // Физическая инженерия поверхности. — 2009. — Т. 7, № 1-2. — С. 23-27. — Бібліогр.: 9 назв. — англ. 1999-8074 https://nasplib.isofts.kiev.ua/handle/123456789/7945 It has been determined by Auger-analysis method, roentgenofluorescence method, and the diffraction analysis that dark spots which appear in the examined steel under cyclic loading are new phases. У статті представлені результати отримані за допомогою оже-електронної спектроскопії (AES), дифракція рентгенівських променів (XRD), атомно-силової мікроскопії (AFM), рентгенофлюоресцентного аналізу, растрової і оптичної мікроскопії по дослідженню зразків СТ 3. Після циклічного навантаження показаний зв’язок між втомними характеристиками і физико-хімічними і механічними властивостями. В статье представлены результаты полученные с помощью оже-электронной спектроскопии (AES), дифракция рентгеновских лучей (XRD), атомно-силовой микроскопии (AFM), рентгенофлюоресцентного анализа, растровой и оптической микроскопии по исследованию образцов СТ 3. После циклической нагрузки показана связь между усталостными характеристиками и физико-химическими и механическими свойствами. en Науковий фізико-технологічний центр МОН та НАН України Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading Вивчення структури фізико-хімічних і механічних властивостей маловуглецевої сталі після циклічного навантаження Изучение структуры физико-химических и механических свойств малоуглеродистой стали после циклической нагрузки Article published earlier |
| spellingShingle | Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading Gorbachyov, L.A. Pogrebnjak, A.D. |
| title | Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading |
| title_alt | Вивчення структури фізико-хімічних і механічних властивостей маловуглецевої сталі після циклічного навантаження Изучение структуры физико-химических и механических свойств малоуглеродистой стали после циклической нагрузки |
| title_full | Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading |
| title_fullStr | Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading |
| title_full_unstemmed | Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading |
| title_short | Study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading |
| title_sort | study of structure and physicochemical and mechanical properties in low-carbon steel after cyclic loading |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/7945 |
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