Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions
Creep-fatigue tests of 9Cr-1Mo-V-Nb steel have been conducted under load control with further study of the steel mechanical degradation via microscopic observation, static-mechanical analysis and ultrasonic evaluation. The tempered specimens exhibited a tempered martensitic structure with a high dis...
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
2017
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| Cite this: | Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions / C.S. Kim // Проблемы прочности. — 2017. — № 1. — С. 7-14. — Бібліогр.: 15 назв. — англ. |
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| citation_txt | Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions / C.S. Kim // Проблемы прочности. — 2017. — № 1. — С. 7-14. — Бібліогр.: 15 назв. — англ. |
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| description | Creep-fatigue tests of 9Cr-1Mo-V-Nb steel have been conducted under load control with further study of the steel mechanical degradation via microscopic observation, static-mechanical analysis and ultrasonic evaluation. The tempered specimens exhibited a tempered martensitic structure with a high dislocation density in the lath interior and fine precipitates on the previous austenite grain and martensite lath boundaries. However, the major microstructure changes to the 9Cr-1Mo-V-Nb steel caused by creep-fatigue were the coarsening of Cr23C6 precipitates, the recovery of dislocations due to rearrangement and annihilation, an increase in the martensite lath width, and the formation of cavities. The ultrasonic velocity was observed to increase rapidly within the initial fatigue life fraction (stage I), but the attenuation decreased during this stage. During stage II, there was a slight increase in the ultrasonic velocity and the attenuation subsequently decreased. The ultrasonic velocity decreased and the attenuation increased during the final period (stage III) of fatigue life.
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SCI EN TI FIC AND TE C H N IC A L
SEC TI O N
UDC 539.4
Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue
Interaction Conditions
C. S. K im
Department of Materials Science and Engineering, Chosun University, Gwangju, Korea
chs2865@chosun.ac.kr
Creep-fatigue tests o f 9Cr-1Mo-V-Nb steel have been conducted under load control with further
study o f the steel mechanical degradation via microscopic observation, static-mechanical analysis
and ultrasonic evaluation. The tempered specimens exhibited a tempered martensitic structure with a
high dislocation density in the lath interior and fine precipitates on the previous austenite grain and
martensite lath boundaries. However, the major microstructure changes to the 9Cr-1Mo-V-Nb steel
caused by creep-fatigue were the coarsening o f Cr23C6 precipitates, the recovery o f dislocations due
to rearrangement and annihilation, an increase in the martensite lath width, and the formation o f
cavities. The ultrasonic velocity was observed to increase rapidly within the initial fatigue life
fraction (stage I), but the attenuation decreased during this stage. During stage II, there was a slight
increase in the ultrasonic velocity and the attenuation subsequently decreased. The ultrasonic
velocity decreased and the attenuation increased during the final period (stage III) o f fatigue life.
K eyw ords: 9Cr-1M o-V-Nb, creep-fatigue, degradation, ultrasonic velocity, attenuation.
In tro d u c tio n . The 9% chrom ium low -carbon steels have proved to be quite attractive
m aterials for high-tem perature and high-pressure structures in advanced pow er generation
facilities. In this ferritic material, chrom ium atoms enhance the oxidation resistance at
elevated tem perature; therefore, high chrom ium (9-12% ) steels are m ore suited for
structural m aterial applications than low chrom ium Cr (1-2.25% ) steels w ith increased
tem peratures and pressures in the pow er plants. H igher physical strength values o f high
chrom ium steels can be anticipated by the addition o f N b and V atoms with alloying
elements, w hich are strong carbide and nitride formers. For protection o f the global
environm ent, the utilization o f clean energy has accelerated the ultra-supercritical (USC)
pressure boilers. Recently, the m echanical strength o f high chrom ium steels has been
questioned for long-term application with regard to the stability o f their m icrom echanical
characteristics at high steam temperature. The typical m ethod for choosing a high-
tem perature m aterials is based on the creep strength. A ustenite-based stainless steel is a key
m aterial and candidate from this viewpoint.
However, there is unfavorable stress in pow er p lant facilities because o f large therm al
expansion coefficient o f stainless steel. Ferritic steel has a m uch smaller therm al expansion
coefficient than austenitic steel. The developm ent o f high-tem perature ferritic steel is a
prerequisite to realize the future o f a USC plant. Also, the developm ent o f advanced high
chrom ium steels is favorable for higher steam tem peratures and pressure. During the
lifetim e o f a p lant facilities, the structural m aterials are undergone to various loading and
temperature. O n the one hand, the effects o f the static and cyclic loading on the m aterial
integrity should be considered from the m aterial developm ent stage. There is a softening
© C. S. KIM, 2017
ISSN 0556-171X. Проблемы прочности, 2017, № 1 7
mailto:chs2865@chosun.ac.kr
C. S. Kim
phenom enon o f the m echanical strength during high tem perature exposure because of
precipitate growth, decrease in dislocation density and depletion o f the solute atoms [1-3].
The form ations o f cracks or leaks represent the final steps o f the m aterial damage
processes in the pow er p lant facilities. Even though they are detected during scheduled
inspections, for the estim ating the life tim e o f materials, defects detection during the early
stages o f dam age is desirable so that the service loads can be adjusted and prevented
m aterials failure. N ondestructive evaluation (NDE) for m aterial characterization can also
contribute valuable information. There is clearly a need for m icrostructural m onitoring
techniques, especially those that can be used in-situ w ith m inim al preparation and give a
com prehensive characterization o f the com ponent state. M ost pow er plant m aterials are
ferrom agnetic steels, w hich allow the use o f m agnetic m onitoring and other N D E m ethods
[4-6]. Because ultrasonic w ave propagating in the m aterial to be tested carries m uch
inform ation on the characteristics o f the material, ultrasonic testing is expected to be
available to determ ine the m icrostructure, heat treatm ent, m aterial processing, in-situ
m onitoring and m aintenance o f structural com ponents [7, 8]. U ltrasonic attenuation and
velocity changes are very sensitive to changes in the hardness, y ield strength, fracture
toughness and m icrostructure, such as the dislocation configuration, grain size and phase
transform ation, etc.
In the present study, the m echanical and m icrostructural characteristics o f the ferritic
9Cr-1M o-V-Nb steel subjected to creep-fatigue dam age w ere investigated by observation o f
m icrom echanical changes and ultrasonic nondestructive evaluation.
1. E x p e rim e n ta l P rocedu re . Table 1 shows the chem ical com position o f the tested
materials. The inductively coupled plasm a was used for high-precise analysis. The test
specim ens were heat treated at 1050oC for norm alizing and then tem pered at 760oC. The
creep-fatigue test w as achieved using a fatigue test machine. The hold tim e w as 60 s.
C ylinder-shaped specim ens w ere m achined w ith gauge lengths o f 20 mm, d iam eters o f
10 m m and shoulder radii o f 20 mm, as shown in Fig. 1. The m axim um tensile load was
187 M Pa w ith cyclic trapezoidal w aveform in the basis o f the ASTM E2714-13. The
interruption test w as conducted w ith ratio o f the fatigue cycles (i.e., N /N f ); 0.1, 0.2, 0.4,
0.6, and 0.8. Table 2 shows the interrupt creep-fatigue test conditions (i.e., fatigue life
fraction, cycles, total test duration, and hold time).
T a b l e 1
Chemical Composition of the Test Specimen (wt.%)
C Si Mn P S Ni Cr
0.09 0.23 0.38 0.015 0.013 0.065 8.66
Mo Cu V Al N Nb Fe
0.90 0.04 0.21 0.01 0.035 0.07 Bal.
The m icrostructural characteristics o f the specim en surface have been determ ined by
the scanning electron m icroscopy (SEM ) and optical m icroscopy (OM). For the detailed
cavity evaluation, the surfaces o f the specim ens were prepared using the vibratory finishing
technique to rem ove the residual deform ed surface. X -ray diffraction (XRD) test w as used
to identify the crystalline structures o f prim ary precipitates in 9Cr-1M o-V-Nb steel after
obtaining the precipitate residues from the selectively electrolytic extraction method. A
centrifuge is used to separate precipitate particles and the particles are dry in the air. For
more detailed characterization, the surface replication was conducted w ith carbon sputtering
process and a thin carbon film was finally obtained, w hich w as exam ined by transm ission
8 ISSN Ü556-171X. Проблемы прочности, 2Ü17, № 1
Study o f Mechanical Degradation o f 9Cr-1Mo-V-Nb Steel
T a b l e 2
In terrupt Test Conditions
Fatigue life 10%
0.1N f
20%
0.2N f
40%
0.4N f
60%
0.6N f
80%
0.8N f
100%
N f
60 s (cycle) 330 660 1320 1980 2640 3300
Test duration (h) 6.4 12.8 25.6 38.5 51.3 64.0
Hold duration (h) 5.5 11.0 22.0 33.0 44.0 55.0
electron m icroscopy (TEM). The chem ical com position and crystalline structure of
precipitates w ere evaluated using energy dispersive spectroscopy (EDS) and selective area
diffraction pattern (SADP) to analyze the types o f precipitate formed.
The 3 m m thin disk w as prepared by tw in je t polishing to observe the m atrix
m icrostructures as w ell as the precipitates. The m artensite lath w as exam ined by energy-
filtered transm ission electron m icroscopy (EFTEM ) and calculated using Eq. (1), as follows
[9]:
3L
w = ---------- , (1)
2N L M (1)
where w is the lath width, N l is the num ber o f lath boundaries intersecting a straight line
o f length L , and M is the m agnification o f the micrograph.
The dislocation density (p) was calculated by Eq. (2):
14.4e 2
p _ I T ' ,2)
where b is the Burgers vector o f dislocation and £ is local strain.
The local strain w as obtained from the X -ray diffraction profile. It is possible to
convert to the breadth o f the strain distribution using the H all-W illiam son m ethod [10].
A direct contact technique w as em ployed to m easure the ultrasonic velocity and
attenuation [11]. A piezoelectric transducer (PZT) w as used w ith a nom inal frequency o f
25 M H z and diam eter o f 0.25 inch. The second and third back w all echoes were gated to
neglect the near field effect o f wave, and then calculate the propagating time.
ISSN Ü556-171X. Проблемы прочности, 2Ü17, № 1 9
C. S. Kim
2. R esu lts a n d D iscussion. The ferritic 9Cr-1M o-V-Nb steel was typical tem pered
m artensite m icrostructure after norm alizing and tem pering heat treatment.
F igure 2 depicts surface m icrographs showing fine precipitates along prior austenitic
grain (PAG) boundaries and m artensitic lath boundaries. The grain size was about 18 ^ m
that is m easured w ith SEM m icrographs. In addition, the m artensite lath w idth w as 0.21 ^ m
and it is m easured w ith TEM micrographs.
a b c
Fig. 2. OM, SEM, and TEM micrographs after tempering heat treatment: (a) OM; (b) SEM
micrograph of lath boundary; (c) TEM micrograph of PAGB.
Figure 3 represents the typical surface m orphologies observed by optical m icroscopy
w ith the m axim um tensile hold tim es o f 60 s. W ith increase in fatigue life fraction, the PAG
boundaries are less pronounced, as com pared to the as-tempered specimen.
The precipitate size was slightly increased w ith creep-fatigue duration, as shown in
Fig. 4. Figure 4 com prises FESEM m icrographs, w hich show the m orphologies o f
precipitates after the m axim um tensile hold tim es o f 60 s.
a b c
Fig. 3. OM images showing the surface morphology: (a) 0.2N f ; (b) 0.6N f ; (c) N f .
a b c
Fig. 4. SEM micrographs showing the morphology of the precipitates for a 60 s hold time: (a) 0.1N f ;
(b) 0 .4 N f ; (c) 0 .8N f.
10 ISSN 0556-171X. Проблемы прочности, 2017, № 1
Study o f Mechanical Degradation o f 9Cr-1Mo-V-Nb Steel
The boundary (i.e., PAGB and lath) precipitates were rapidly grown, and thus the
boundaries appeared to be unclear, as previously observed w ith the OM investigation. The
rapid growth of the particles along the PAGB w as thought to be a result of the boundaries
being apt to the prim ary diffusion passage of solute atoms (Cr, Mo, and C), im plying a
diffusion controlled coarsening mechanism. Figure 5 shows the TEM m icrographs of the
precipitate m orphologies in the interrupted test specim ens prepared using the carbon replica
technique. The fatigue failures w as 3300 cycles. The precipitates size slightly increased up
to failure. The increase in the particle size w as about 10%. Cerri et al. [12] reported the
growth o f Nb and C r precipitates in 9Cr steel subjected to creep deform ation at 570 and
645°C. The agglom eration o f precipitates on the grain and lath boundaries w as dominant
for creep deform ation [13]. However, there is little coarsened precipitates during the fatigue
because the fatigue test duration w as too short for changes to occur in the precipitate.
Additionally, it w as observed no softening and coarsening o f the particles for creep-fatigue,
w hich w as tested at a tem perature o f 400°C [14]. Therefore, the slight increase in the
particle size was resulted from the low tem perature and short tim e com pared to long-tim e
creep at high tem peratures o f 9Cr steel.
Fig. 5. TEM micrographs showing the morphology of precipitates for a 60 s hold time: (a) 0.1N f ;
(b) 0.4N f ; (c) 0.8N f ; (d) N f .
The dislocation density in the lath interior decreased w ith creep-fatigue dam age as
shown in Fig. 6. The as-tem pered specim en showed m any thin and elongated lath
substructures. The lath interior shows tangled dislocations w ith a high density. Figure 6c
shows the m icrostructures ju s t after failure. The w idth o f lath boundaries grew during
creep-fatigue, and the dislocation density w ithin the lath interior w as low er than in 0 .4N f
specimen. The increase in the w idth o f laths is attributed to the recovery o f dislocations and
recom bination o f the boundaries. Abe [15] also m entioned that the growth o f the lath
boundary in tem pered m artensitic steel w as a process o f Y-junction movement.
Fig. 6. TEM micrographs showing the martensite lath substructure for a 60 s hold time: (a) 0.1N f ;
(b) 0.4Nf ; (c) N f .
ISSN Ü556-171X. Проблемы прочности, 2Ü17, № 1 11
C. S. Kim
Figure 7 depicts the results o f the cavity observations by OM. These m icrographs
show the surface m orphology observed under a bright field as w ell as the dark field image.
In the bright field images, small b lack spots at the PAG boundary were distinctly observed.
In addition, some w hite spots w ere also observed in the dark field images, w hich support
cavity form ation during creep-fatigue in 9Cr-1M o-V-Nb steel. Cavities w ere presented
along the grain boundaries but not in those o f the as-tem pered specimen.
a b c d
Fig. 7. Optical micrographs showing the surface morphology by bright (a, c) and dark field (b, d)
images; (a, b) as-tempered and (c, d) N f of 60 s.
Figure 8 shows the fractured surface o f the as-tem pered and creep-fatigue dam aged
specim ens w hich fractured at the liquid nitrogen to observe the creep void formation. As
m arked by the arrows, small cavities clearly appeared in the fractured specimen.
Fig. 8. SEM secondary electron images showing the fractured surface morphology in the LNT:
(a) as-tempered and (b) N f .
c
$c
■ MX
«
- I J
i I f 1 * *
* * 7 *
h ' f tv*
1 Nf
0 .6 N,
35 4 0 4 5 50 55 60 65 70 75
20
80
Fig. 9. X-ray diffraction profiles of electrically extracted precipitate residues showing the typical
precipitates of 9Cr-1Mo-V-Nb steel.
12 ISSN 0556-171X. npoôneMbi npouuocmu, 2017, № 1
Study o f Mechanical Degradation o f 9Cr-lMo-V-Nb Steel ...
Fig. 10. The typical precipitates of 9Cr-1Mo-V-Nb steel showing SAD patterns of precipitates and
their EDS results: (a) equiaxed and coarsened M23C6 carbide; (b) elongated and rod type M23C6
carbide; (c) spherical type MX precipitate; (d) EDS results of the same precipitate as (a); (e) EDS
results of the same precipitate as (c).
The crystalline analysis for the precipitates using X -ray diffraction m easurem ents on
the extracted residues is shown in Fig. 9. The particles w ere identified as M 23C6 carbide and
M X phase for the as-tem pered specim en. In this study, no other precipitation took place
during creep-fatigue at a tem perature o f 550oC. For a deeper insight, the precipitates were
analyzed using the SADP and EDS methods.
Figure 10 shows typical SAD patterns o f the precipitates w ith different m orphologies
(i.e., equiaxed, coarsened, elongated and spherical type). Figure 10a shows the M 23C 6
carbide w ith an equiaxed and coarsened m orphology type. Figure 10b also shows the
M 23C 6 carbide w ith an elongated and rod like m orphology type. Figure 10c shows the M X
carbide w ith a fine and spherical m orphology type. The EDS result shows the chemical
com position o f C r23C 6 and (N b,V )C precipitates. The M 23C 6 carbides are present as
(Cr,Fe,M o)23C6 and (NbxV i-xCN) types, where x varies from one to zero. In addition to
these precipitates, Laves Fe2(M o,W ) phases have been reported to nucleate at the martensite
lath boundaries w ith a h igh growth rate, w hich has a m ajor effect on the mechanical
strength reduction. However, no Laves phases w ere observed for creep-fatigue at 550OC.
Conclusions. The change in the dislocation density was concentrated in the early
stage o f the fatigue life, w ithin 0.2N f . The dislocation density decreased, but the size o f
the precipitates only slightly increased. The w ave velocity increased rapidly w ithin the
initial fatigue life fraction, 0.2N f (i.e., stage I), but the attenuation decreased, w hich was
attributed to the decrease in the dislocation density because o f rearrangem ent and recovery.
During stage II, a slight increase in the w ave velocity, betw een 0.2N f and 0.8N f o f the
fatigue life fraction, is attributed to the depletion o f solute atoms as a result o f coarsening of
the M 23C 6 carbide. The attenuation during this stage subsequently decreased due to the
growth o f the lath width. The ultrasonic velocity decreased and the attenuation increased
during the final period (i.e., stage III) o f fatigue life, as a result o f the cavities generated by
creep-fatigue. Therefore, the creep-fatigue degradation o f 9Cr-1M o-V-Nb steel could be
nondestructively evaluated by m easuring the ultrasonic velocity and attenuation.
A cknow ledgm ents. This research was supported by the National Research Foundation
o f K orea (NRF) Grant funded by the K orean G overnm ent (NRF-2013M 2A2A9043241).
1. P. J. Ennis, A. Z ielinska-L ipiec, O. W achter, and A. C zyrska-Filem onow icz,
“M icrostructural stability and creep rupture strength o f the m artensitic steel P92 for
advanced pow er plant,” A cta M ater., 45, No. 12, 4901-4907 (1997).
ISSN 0556-171X. npodneMbi nponnocmu, 2017, № l 13
C. S. Kim
2. F. Abe, T. Horiuch, M. Taneike, and K. Sawada, “Stabilization o f martensitic
m icrostructure in advanced 9Cr steel during creep at high tem perature,” M ater. Sci.
Eng. A, 378, 299-303 (2004).
3. G. Eggeler, “The effect o f long-term creep on particle coarsening in tem pered
m artensite ferritic steels,” A cta M etal., 37, No. 12, 3225-3234 (1989).
4. R. H. L atiff and N. F. Fiore, “U ltrasonic attenuation in spheroidized steel,” J. Appl.
Phys., 45, 5182-5186 (1974).
5. J. K rautkräm er and H. Krautkräm er, Ultrasonic Testing o f M aterials, Springer-Verlag,
B erlin-H eidelberg (1990).
6. O. V. A bram ov, U ltrasound in L iqu id and Solid M etals, CRC Press, N ew Y ork
(1994).
7. R. Truell, C. Elbaum, B. B. Chick, Ultrasonic M ethods in So lid State Physics,
Academ ic Press, N ew Y ork (1969).
8. D. N. Collins and W. Alcheikh, “U ltrasonic non-destructive evaluation o f the m atrix
structure and the graphite shape in cast iron,” J. M ater. Process. Tech., 55, No. 2,
85-90 (1995).
9. K. V. Rasm ussen and O. B. Pedersen, “Fatigue o f copper polycrystals at low plastic
strain am plitudes,” A cta M etall., 28, No. 11, 1467-1476 (1980).
10. G. K. W illiam son and W. H. Hall, “X -ray line broadening from filed aluminum and
w olfram ,” A cta M etall., 1, No. 1, 22-31 (1953).
11. I. K. Park, U. S. Park, and C. S. Kim, “A study on the evaluation o f m aterial
degradation for 2.25Cr-1M o steel by ultrasonic m easurem ents,” Trans. Korea Soc.
Mach. Tool Eng., 10, 61-67 (2001).
12. E. Cerri, E. Evangelista, S. Spigarelli, and P. Bianchi, “Evolution o f m icrostructure in
a m odified 9C r-1M o steel during short term creep,” M ater. Sci. Eng. A, 245, 285-292
(1998).
13. H. Okamura, R. Ohtani, K. Saito, et al., “Basic investigation for life assessment
technology o f m odified 9Cr-1M o steel,” Nucl. Eng. Des., 193, No. 3, 243-254 (1999).
14. H. Sakasegawa, T. Hirose, A. Kohyama, et al., “M icrostructural stability o f reduced
activation ferritic/m artensitic steels under high tem perature and stress cycling,”
Fusion Eng. Des., 61-62, 671-675 (2002).
15. F. Abe, “Coarsening behavior o f lath and its effect on creep rates in tem pered
m artensitic 9C r-W steels,” M ater. Sci. Eng. A , 387-389, 565-569 (2004).
Received 30. 08. 2016
14 ISSN 0556-171X. npoÖÄeubi 2017, № 1
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| id | nasplib_isofts_kiev_ua-123456789-173577 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0556-171X |
| language | English |
| last_indexed | 2025-12-07T16:51:40Z |
| publishDate | 2017 |
| publisher | Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| record_format | dspace |
| spelling | Kim, C.S. 2020-12-12T13:26:07Z 2020-12-12T13:26:07Z 2017 Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions / C.S. Kim // Проблемы прочности. — 2017. — № 1. — С. 7-14. — Бібліогр.: 15 назв. — англ. 0556-171X https://nasplib.isofts.kiev.ua/handle/123456789/173577 539.4 Creep-fatigue tests of 9Cr-1Mo-V-Nb steel have been conducted under load control with further study of the steel mechanical degradation via microscopic observation, static-mechanical analysis and ultrasonic evaluation. The tempered specimens exhibited a tempered martensitic structure with a high dislocation density in the lath interior and fine precipitates on the previous austenite grain and martensite lath boundaries. However, the major microstructure changes to the 9Cr-1Mo-V-Nb steel caused by creep-fatigue were the coarsening of Cr23C6 precipitates, the recovery of dislocations due to rearrangement and annihilation, an increase in the martensite lath width, and the formation of cavities. The ultrasonic velocity was observed to increase rapidly within the initial fatigue life fraction (stage I), but the attenuation decreased during this stage. During stage II, there was a slight increase in the ultrasonic velocity and the attenuation subsequently decreased. The ultrasonic velocity decreased and the attenuation increased during the final period (stage III) of fatigue life. This research was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (NRF-2013M2A2A9043241). en Інститут проблем міцності ім. Г.С. Писаренко НАН України Проблемы прочности Научно-технический раздел Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions Определение степени ухудшения механических характеристик стали 9Cr-lMo-V-Nb в условиях взаимодействия ползучести и усталости Article published earlier |
| spellingShingle | Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions Kim, C.S. Научно-технический раздел |
| title | Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions |
| title_alt | Определение степени ухудшения механических характеристик стали 9Cr-lMo-V-Nb в условиях взаимодействия ползучести и усталости |
| title_full | Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions |
| title_fullStr | Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions |
| title_full_unstemmed | Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions |
| title_short | Study of Mechanical Degradation of 9Cr-1Mo-V-Nb Steel under Creep-Fatigue Interaction Conditions |
| title_sort | study of mechanical degradation of 9cr-1mo-v-nb steel under creep-fatigue interaction conditions |
| topic | Научно-технический раздел |
| topic_facet | Научно-технический раздел |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/173577 |
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