Failure Analysis of a Heavy Duty Gas Turbine Blad
This paper reports the failure analysis of a blade in a heavy duty land-base gas turbine. The power plant is located near the coastal area and also in vicinity of deserts of Iran, as a consequence, the airborne pollutants entering with the inlet air into the turbine. Most of the blades from one sta...
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
2014
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| Zitieren: | Failure Analysis of a Heavy Duty Gas Turbine Blad / S. Asadikouhanjani, M. Torfeh, R. Ghorbanf // Проблемы прочности. — 2014. — № 5. — С. 35-40. — Бібліогр.: 4 назв. — англ. |
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irk-123456789-1731642020-11-26T01:26:25Z Failure Analysis of a Heavy Duty Gas Turbine Blad Asadikouhanjan, i S. Torfeh, M. Ghorbanf, R. Научно-технический раздел This paper reports the failure analysis of a blade in a heavy duty land-base gas turbine. The power plant is located near the coastal area and also in vicinity of deserts of Iran, as a consequence, the airborne pollutants entering with the inlet air into the turbine. Most of the blades from one stage of this gas turbine had deteriorated after nearly 25,000 EOH of service. One of these blades was broken through the airfoil from the section located at almost two-third of span. The predicted service life was 100,000 h. The turbine runs with gasoline and filtered air. The broken blade was received for study. The objective of the present work is to determine the root cause of the blade failure. Выполнен анализ разрушения лопатки ГТД после 25 тыс. ч. эксплуатации. При этом использовались методики оценки фрактографических и металлургических характеристик материала. Данные фрактографического анализа показывают, что инициирование трещин происходит в пере лопатки в очагах высокотемпературного коррозионного питтинга, а распространяются они по механизму высокотемпературной коррозионной усталости, в результате чего имеет место хрупкое разрушение. Проаналізовано руйнування лопатки ГТД після 25 тис. годин експлуатації. При цьому використовувалися методики оцінки фрактографічних і металургійних характеристик матеріалу. Дані фрактографічного аналізу показують, що ініціювання тріщин відбувається в пері лопатки в осередках високотемпературного корозійного пітингу, а розповсюджуються вони по механізму високотемпературної корозійної утоми, в рузультаті чого має місце крихке руйнування. 2014 Article Failure Analysis of a Heavy Duty Gas Turbine Blad / S. Asadikouhanjani, M. Torfeh, R. Ghorbanf // Проблемы прочности. — 2014. — № 5. — С. 35-40. — Бібліогр.: 4 назв. — англ. 0556-171X http://dspace.nbuv.gov.ua/handle/123456789/173164 539.4 en Проблемы прочности Інститут проблем міцності ім. Г.С. Писаренко НАН України |
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Научно-технический раздел Научно-технический раздел Asadikouhanjan, i S. Torfeh, M. Ghorbanf, R. Failure Analysis of a Heavy Duty Gas Turbine Blad Проблемы прочности |
| description |
This paper reports the failure analysis of a blade in a
heavy duty land-base gas turbine. The power plant is located near the coastal area and also in vicinity of deserts of Iran, as a consequence, the airborne pollutants entering with the inlet air into the turbine. Most of the blades from one stage of this gas turbine had deteriorated after nearly 25,000 EOH of service. One of these blades was broken through
the airfoil from the section located at almost two-third of span. The predicted service life was 100,000 h. The turbine runs with gasoline and filtered air. The broken blade was received for study. The objective of the present work is to determine the root cause of the blade failure. |
| format |
Article |
| author |
Asadikouhanjan, i S. Torfeh, M. Ghorbanf, R. |
| author_facet |
Asadikouhanjan, i S. Torfeh, M. Ghorbanf, R. |
| author_sort |
Asadikouhanjan, i S. |
| title |
Failure Analysis of a Heavy Duty Gas Turbine Blad |
| title_short |
Failure Analysis of a Heavy Duty Gas Turbine Blad |
| title_full |
Failure Analysis of a Heavy Duty Gas Turbine Blad |
| title_fullStr |
Failure Analysis of a Heavy Duty Gas Turbine Blad |
| title_full_unstemmed |
Failure Analysis of a Heavy Duty Gas Turbine Blad |
| title_sort |
failure analysis of a heavy duty gas turbine blad |
| publisher |
Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| publishDate |
2014 |
| topic_facet |
Научно-технический раздел |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/173164 |
| citation_txt |
Failure Analysis of a Heavy Duty Gas Turbine Blad / S. Asadikouhanjani, M. Torfeh, R. Ghorbanf // Проблемы прочности. — 2014. — № 5. — С. 35-40. — Бібліогр.: 4 назв. — англ. |
| series |
Проблемы прочности |
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AT asadikouhanjanis failureanalysisofaheavydutygasturbineblad AT torfehm failureanalysisofaheavydutygasturbineblad AT ghorbanfr failureanalysisofaheavydutygasturbineblad |
| first_indexed |
2025-07-15T09:41:48Z |
| last_indexed |
2025-07-15T09:41:48Z |
| _version_ |
1837705472284557312 |
| fulltext |
UDC 539.4
Failure Analysis of a Heavy Duty Gas Turbine Blade*
S. Asadikouhanjani,
1
M. Torfeh, and R. Ghorbanf
Mapna Turbine Blade Engineering & Manufacturing Company, Iran
1 asadi.saeed@mapnablade.com
ÓÄÊ 539.4
Àíàëèç ðàçðóøåíèÿ âûñîêîíàãðóæåííîé ëîïàòêè ÃÒÄ
Ñ. Àñàäèêóõàíäæàíè, Ì. Òîðôåõ, Ð. Ãîðáàíô
Íàó÷íî-ïðîèçâîäñòâåííàÿ êîìïàíèÿ “Ìàïíà”, ïðîèçâîäèòåëü ëîïàòîê ÃÒÄ, Òåãåðàí, Èðàí
Âûïîëíåí àíàëèç ðàçðóøåíèÿ ëîïàòêè ÃÒÄ ïîñëå 25 òûñ. ÷. ýêñïëóàòàöèè. Ïðè ýòîì èñïîëü-
çîâàëèñü ìåòîäèêè îöåíêè ôðàêòîãðàôè÷åñêèõ è ìåòàëëóðãè÷åñêèõ õàðàêòåðèñòèê ìàòå-
ðèàëà. Äàííûå ôðàêòîãðàôè÷åñêîãî àíàëèçà ïîêàçûâàþò, ÷òî èíèöèèðîâàíèå òðåùèí ïðî-
èñõîäèò â ïåðå ëîïàòêè â î÷àãàõ âûñîêîòåìïåðàòóðíîãî êîððîçèîííîãî ïèòòèíãà, à ðàñïðî-
ñòðàíÿþòñÿ îíè ïî ìåõàíèçìó âûñîêîòåìïåðàòóðíîé êîððîçèîííîé óñòàëîñòè, â ðåçóëüòàòå
÷åãî èìååò ìåñòî õðóïêîå ðàçðóøåíèå.
Êëþ÷åâûå ñëîâà: àíàëèç ðàçðóøåíèÿ, âûñîêîòåìïåðàòóðíàÿ êîððîçèÿ 2-ãî òèïà,
âûñîêîòåìïåðàòóðíàÿ êîððîçèîííàÿ óñòàëîñòü, ÃÒÄ.
Introduction. Generally speaking, most of blades and vanes have severe operation
conditions characterized by the following factors:
(i) operation environment (fuel and air contamination, solid particles);
(ii) high mechanical stresses (due to centrifugal force, vibratory and flexural stresses);
(iii) high thermal stresses (due to thermal gradients).
Among them, fuel and air contamination can cause hot corrosion which can consume
the material at an unpredictably rapid rate [1]. Consequently, the load-carrying ability of the
component is reduced or the risk of HCF increases and results in a reduction of engine
reliability and availability. In the gas turbines, the air and fuel frequently contain corrosive
contaminants that can cause serious hot corrosion problems. Hot corrosion may be defined as
an accelerated corrosion, resulting from the presence of salt contaminants such as Na2SO4,
NaCl, and V2O5 that combine to form molten deposits, which will damage the protective
surface oxides [2]. A wide range of fuels can be used in gas turbines (ranging from clean
gas to crude oil), and these fuels can contain sulfur, sodium, potassium, vanadium, lead,
and molybdenum as contaminants. The airborne pollutants entering with the inlet air
depend on the turbine location, but include sodium, sulfur, chlorine and calcium. Especially
onshore power plants, where salt spray may occur, are exposed to the fouling of
compressors, and even hot salt corrosion of the turbine blading [3]. These impurities in the
fuel and the air can lead to the deposition of alkali metal sulphates such as Na2SO4 on the
blade or vane surfaces, resulting in the hot corrosion attack [2]. Two types of hot corrosion
reactions are known to occur in gas turbines. A high temperature reaction, known as type I
hot corrosion, which occurs at 850 to 1000�C after a short incubation period. A low
© S. ASADIKOUHANJANI, M. TORFEH, R. GHORBANF, 2014
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2014, ¹ 5 35
* Report on International Scientific Conference “Fatigue and Thermofatigue of Materials and
Structural Components” (Kiev, 2013).
temperature reaction, also referred to as type II hot corrosion, is favored at 600 to 750�C
after a long incubation period [4]. This paper reports the failure analysis of a blade in a
heavy duty land-base gas turbine. The power plant is located near the coastal area and also
in vicinity of deserts of Iran, as a consequence, the airborne pollutants entering with the
inlet air into the turbine. Most of the blades from one stage of this gas turbine had
deteriorated after nearly 25,000 EOH of service. One of these blades was broken through
the airfoil from the section located at almost two-third of span. The predicted service life
was 100,000 h. The turbine runs with gasoline and filtered air. The broken blade was
received for study. The objective of the present work is to determine the root cause of the
blade failure.
Experimental. In order to make an insight into the premature failure of the damaged
blades, one of the broken blades was taken for investigation. The blade was removed from
the turbine after trip due to high level of vibration. The received blade was subjected to a
series of examinations, including visual and fractographic examinations. Optical and
scanning electron microscops (SEM) equipped with an X-ray energy dispersive spectrometer
(EDS) were used to observe the microstructure and analyze the chemical composition of
local regions.
Results and Discussion.
Visual Examination. The as-received blades are shown in Fig. la. The surface of the
blades exhibited deterioration or signs of corrosion, and many deposits can be seen on them.
The deposits can be removed easily and underneath of them there are many pits at the surface
of the blades (Fig. 1b). Consequently, the surface of the blade was uneven and rugged, and
base metal of the blade appeared to be damaged and/or missing in several areas.
Furthermore visual evaluations revealed that one of the blades was cut off at 12 cm
from tip, about two–third of the airfoil span (Fig. 2a), showed fatigue marks at the fracture
surface, which is presented in Fig. 2b. So, a series of analysis were performed on this blade
to identify the possible cause of failure. Moreover, the detached piece of the blade had
caused some damage to other blades and the exhaust inner wall.
Investigation of Corroded Blades. Typical results of investigation for corroded blades
are described as follows:
The blade under investigation was covered with mixed thin deposits, which showed
blackish. The deposits have been sampled for the analysis, and then blade’s airfoil has been
cut off for metallographic evaluation by grinding, polishing, and etching. According to
S. Asadikouhanjani, M. Torfeh, and R. Ghorbanf
36 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2014, ¹ 5
a b
Fig. 1. Overview of the damaged blades (a); existence of pits underneath of deposits (b).
Fig. 3, EDS analysis of deposit revealed that its components contained several percents of
S, Na, Ca, O, and V, as contaminant elements (probably in the form of corrosive
components of Na2SO4 and V2Os). Existence of these components makes the blade
susceptible to occurrence of hot corrosion of types I and II.
Failure Analysis of a Heavy Duty Gas Turbine Blade
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2014, ¹ 5 37
a
b
Fig. 2. Broken blade (a); fracture surface of the broken blade with fatigue marks (b).
Fig. 3. Chemical composition of the deposits.
A typical cross-sectional microstructure of severely corroded part is shown in Fig. 4.
A layer type of hot corrosion with an uneven scale base metal interface without any
subscale sulphides and precipitate-depleted zones was found to be present. According to
results of visual examination, chemical and metallographic analysis, type II of hot corrosion
is an active damaging mechanism in this turbine.
Fractographic Analysis. The upper view of the broken blade is presented in Fig. 5a.
The general orientation of the fracture surface is nearly 45� to the longitudinal axis of the
blade (Fig. 5b). Three distinct regions denoted by I, II, and III in Fig. 5a can be identified
at the fracture surface. Visual examination clearly showed the typical fatigue fracture
surface with a propagation area and a final fracture zone (Fig. 5a). The fracture mechanism
in three regions is analyzed by SEM. Details of the fracture surface are shown in Fig. 5c–e.
Region I shows a dark fracture surface. EDS analysis of the fracture surface in this region
revealed the presence of S, Na, O as corrosive elements. In addition, some isolated typical
fatigue striations could be identified in region I. In fact, the fracture surface of region I was
corroded by some components like Na2S04, or a mixed mode of fatigue-hot corrosion
mechanism seems to occur. Details of the fracture surface of region II shows sharp fatigue
striations (Fig. 5d). In regions I and II, the crack propagation occurred in the pressure-
suction side direction. Region III reveals a rough dendritic fracture surface. This is the sign
of a final fracture because of the overload.
Discussion. Alloy surfaces exposed to high temperatures and gas environments can
become coated with foreign deposits (sulfates, oxides, chlorides, etc.) from combustion air
or fuel contaminants. These corrosive components react with the surface of the blade and
layer-type corrosion (type II) characterized by an uneven scale/metal interface and the
absence of subscale sulphides has been observed. Hot corrosion of type II forms typical
pitting. Occurrence of pitting at the surface of the blades and existence of alternative
aerodynamic loads on them make the blades prone to HCF.
Conclusions. As for the hot corrosion-fatigue damages observed in a blade of high-
temperature heavy duty gas turbine, following results were obtained.
1. The corrosion was that of a typical hot corrosion type II caused by Na2S04.
2. The hot corrosion is caused by a large quantity of corrosive impurities present in
the air which get into the gas turbine, in addition to those in the fuel.
38 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2014, ¹ 5
Fig. 4. SEM micrograph of the corroded blade material.
S. Asadikouhanjani, M. Torfeh, and R. Ghorbanf
3. Hot corrosion of type II forms typical pitting that make the blades prone to HCF.
4. In order to prevent the hot corrosion, the air and fuel filter should be reinforced,
and CoCrAIYRe (VPS) or NiCoCrAIY (VPS) coating with higher anticorrosive properties
should be used over the surface of the blade.
Acknowledgments. The authors would like to thank the R&D centre of MAPNA
group for their support.
Ð å ç þ ì å
Ïðîàíàë³çîâàíî ðóéíóâàííÿ ëîïàòêè ÃÒÄ ï³ñëÿ 25 òèñ. ãîäèí åêñïëóàòàö³¿. Ïðè
öüîìó âèêîðèñòîâóâàëèñÿ ìåòîäèêè îö³íêè ôðàêòîãðàô³÷íèõ ³ ìåòàëóðã³éíèõ õàðàê-
òåðèñòèê ìàòåð³àëó. Äàí³ ôðàêòîãðàô³÷íîãî àíàë³çó ïîêàçóþòü, ùî ³í³ö³þâàííÿ òð³-
ùèí â³äáóâàºòüñÿ â ïåð³ ëîïàòêè â îñåðåäêàõ âèñîêîòåìïåðàòóðíîãî êîðîç³éíîãî
ï³òèíãó, à ðîçïîâñþäæóþòüñÿ âîíè ïî ìåõàí³çìó âèñîêîòåìïåðàòóðíî¿ êîðîç³éíî¿
óòîìè, â ðóçóëüòàò³ ÷îãî ìຠì³ñöå êðèõêå ðóéíóâàííÿ.
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2014, ¹ 5 39
a
c d e
Fig. 5. General view of the fracture surface (a); higher magnification of three regions (b); presence of
striations and corrosion products in region I (c); presence of striation in region II (d); dendritic
fracture surface in region III (e).
b
Failure Analysis of a Heavy Duty Gas Turbine Blade
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Anal., 11, No. 4, 589–597 (2004).
3. F. Starr, N. Wood, and R. Robertson, “Investigation of hot salt corrosion at a
land-based gas turbine installation,” J. Phys. IV France, 03, C9-779–C9-786 (1993).
4. A. K. Koul, J. P. Immarigeon, R. V. Dainty, and P. C. Patnaik, “Degradation of high
performance aero-engine turbine blades,” in: V. P. Swaminathan and N. S. Cheruvu
(Eds.), Advanced Materials and Coatings for Combustion Turbines, Published by
ASM International, Materials Park, OH (1994), pp. 69–74.
Received 14. 11. 2013
40 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2014, ¹ 5
S. Asadikouhanjani, M. Torfeh, and R. Ghorbanf
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