1
Assessmen o C i ical Condi ions o
Co osion Fa igue C ack Ini ia ion Li e o S ainless S eel
Won Beom Kim1,* and Hi oshi Yajima2
1 Depa men o Na al A chi ec u e and Ocean Enginee ing, Ulsan College, Ulsan, Ko ea
2Depa men o Mechanical Enginee ing, Nagasaki Ins i u e o Applied Science, Nagasaki, Japan
Abs ac . In his s udy, co osion a igue c ack ini ia ion es s we e conduc ed using 13C s ainless s eel in a
3% NaCl aqueous solu ion o in es iga e he co osion a igue c ack ini ia ion li e (Nc). Fo his pu pose, he
ini ia ion o a c ack om a co osion pi was di ec ly obse ed. In pa icula , c e ice co osion condi ions we e
in oduced o one specimen o induce he o ma ion o a co osion pi wi hin a designa ed obse a ion a ea. In
addi ion, a model desc ibing co osion a igue c ack ini ia ion and p opaga ion was p oposed. To da e, he
concep o co osion a igue c ack ini ia ion li e has been ambiguously de ined. The key aspec o he p oposed
model is iden i ying he poin in he co osion a igue c ack ini ia ion li e when he co osion pi eaches i s
c i ical size and ansi ions in o a c ack. Since a c ack ini ia ing om a pi is gene ally small, i was ega ded
as a small c ack and e alua ed using he in insic c ack model. When he co osion pi was conside ed a small
c ack, he c i ical condi ions o co osion a igue c ack ini ia ion we e e alua ed by compa ing he s ess
in ensi y ac o (ΔK) wi h he c ack leng h–dependen h eshold s ess in ensi y ac o , (ΔK h)s. The esul s o
his s udy indica e ha he c i ical condi ion o co osion a igue c ack ini ia ion can be es ima ed by
de e mining (ΔK h)s h ough he in insic c ack model. Based on hese indings, he ollowing conclusion was
d awn: when no dis inc s ess concen a ion poin is associa ed wi h he co osion a igue c ack ini ia ion li e,
he momen when he a igue c ack p opaga ion a e su passes he co osion pi g ow h a e— he eby causing
he a igue c ack o ini ia e om he pi and p opaga e signi ican ly—can be de ined as a easonable and
uni e sal c i e ion o co osion a igue c ack ini ia ion li e (Nc).
Keywo ds: Co osion a igue c ack ini ia ion li e, Co osion pi , C e ice co osion, Pi - o-c ack, 13C
s ainless s eel
1. In oduc ion
In s uc u al componen s ope a ing in co osi e en i onmen s, co osion a igue c ack ini ia ion li e (Nc) has
adi ionally been ea ed ambiguously in cases whe e no appa en s ess concen a o s—such as geome ic
discon inui ies o welded join s—a e p esen . Pa icula ly, when a igue c acks a e ini ia ed by s ess concen a ion
e ec s induced by co osion pi s alone, he e emain issues o be esol ed be o e a clea and consis en amewo k
o e alua ing Nc can be es ablished.
Fa igue c acks in co osi e en i onmen s end o ini ia e ea lie han hose in a mosphe ic condi ions due o he
syne gis ic e ec s o co osion and cyclic loading. The e o e, in o de o ensu e he s uc u al eliabili y o s eel
componen s and o acili a e mo e a ional a igue design, i is essen ial o clea ly de ine a gene alized c i e ion o
co osion a igue c ack ini ia ion li e (Nc) . In his ega d, many esea che s ha e conduc ed s udies ela ed o
c ack ini ia ion induced by co osion pi s. To da e, he ollowing insigh s ha e been es ablished.
Fo ma ensi ic 12–13%C s ainless s eels used in chlo ide-bea ing and CO₂–b ine en i onmen s, co osion-
a igue (CF) du abili y is equen ly ini ia ion-con olled. Repea ed obse a ions iden i y co osion pi s as
dominan c ack s a e s, wi h passi e- ilm up u e unde cyclic s ain p eceding pi -con olled ini ia ion. Unde
ee-co osion CO₂/Cl⁻ condi ions, localized a ack a su ace ea u es (e.g., machining ma ks) p omo es he
sequence su ace s a e → pi o ma ion → c ack nuclea ion.
In high-cycle a igue, ini ia ion a co osion de ec s in solu ion leads o a ma ked d op in s eng h e sus ai ,
consis en wi h in-si u elec ochemical e idence o passi e- ilm b eakdown du ing cycling [1–4].
In addi ion, o isola e pi se e i y, nume ous s udies ha e p e-condi ioned pi s by con olled exposu e o
elec ochemis y. In aus eni ic g ades (e.g., 304/316), elec ochemically induced pi s in chlo ide media educe he
endu ance limi , and simple √a ea app oaches can o e es ima e a igue limi s in he p esence o pi s.
* Co espondence o: [email protected]
16 h In e na ional Symposium on P ac ical Design o Ships and O he Floa ing S uc u es PRADS 2025
Ann A bo , MI, USA, Oc obe 19 h – 23 d 2025
2
In PH-ma ensi ic 17-4PH blade s eels, single dep h-con olled pi s (≈100–250 µm) educe he endu ance limi
by ≈45–65%. Once an empi ical geome y ac o is calib a ed, El-Haddad/Ki agawa–Takahashi small-c ack
amewo ks cap u e he pi e ec ; nea - h eshold g ow h in chlo ide solu ions shows closu e-a ec ed beha io
wi h R- a io sensi i i y [5–8].
Fu he mo e, a cen al modeling challenge is he pi - o-c ack ansi ion and he beha io o sho (small) c acks,
which may p opaga e e en below he long-c ack h eshold ΔK h due o size e ec s, c ack-closu e, o
en i onmen al assis ance. Recen sho -c ack mic os uc u al models explici ly ea pi s as mic o-no ches o
quan i y S–N knock-downs and ansi ion c i e ia. Ac oss dilu e- o-concen a ed chlo ide condi ions in
p ecipi a ion-ha dened (PH) ma ensi ic s eels, o al li e inc eases mainly h ough longe ini ia ion li e as chlo ide
dec eases, whe eas long- and sho -c ack p opaga ion shows compa a i ely weake chlo ide dependence. Classic
NASA analyses and subsequen e iews ame CF c ack- ip kine ics as a supe posi ion o cyclic a igue and ime-
dependen (chemical/SCC) p ocesses, p o iding a mechanis ic basis o h eshold-based assessmen s when pi s
a e ea ed as e ec i e small c acks [9–13].
F om he abo e, o 13C s ainless s eels in chlo ide-bea ing media, he o egoing e idence shows CF li e is
go e ned p ima ily by ini ia ion om co osion de ec s, wi h pi geome y (size/acui y), mean s ess (R- a io), and
en i onmen ([Cl⁻], po en ial, empe a u e, oxygena ion) con olling he knock-down ela i e o ai . This mo i a es
a s udy ha (i) ea s obse ed pi s as small c acks wi hin an in insic-leng h/ h eshold amewo k, (ii) quan i ies
ini ia ion li e agains measu ed pi geome y and en i onmen , and (iii) consis en ly couples his wi h nea -
h eshold c ack-g ow h da a (including R-dependence/closu e) o deli e se ice- ele an li e p edic ion o 13C .
Consis en wi h his app oach, p io wo k on 13C demons a ed an ope a ional de ini ion o Nc by di ec ly linking
pi g ow h o small-c ack mechanics: ini ia ion occu s a he ins an when he a igue c ack g ow h a e i s
o e akes he pi g ow h a e, ma king he onse o genuine c ack p opaga ion om a pi . In ha wo k (syn he ic
seawa e , 60 °C, R=0.1, 1.7 Hz), pi s we e ea ed as small c acks; he in insic c ack model (ICM)[14] p o ided
he assessmen basis.
The measu ed c i ical ΔK a ini ia ion lay below he long-c ack h eshold ye con o med o he ICM end, and
in e se ac og aphy wi h he Newman–Raju solu ion ep oduced obse ed c ack-leng h his o ies— alida ing
bo h he Nc de ini ion and he ICM-based h eshold assessmen o 13C [15].
The p esen s udy adop s his gene alized de ini ion o Nc o c acks ini ia ed om small co osion pi s, and
examines i s alidi y h ough expe imen s in 3% NaCl using 13C s ainless s eel (SUS410J1) coupled wi h a
ac u e-mechanics-based analysis inco po a ing he ICM .
In pa icula , whe eas many p io in es iga ions elied on a i icial pi s o p ac icali y, expe imen s ha
gene a e and ollow na u ally o med pi s unde simula ed se ice condi ions a e a e. To cap u e he co-e ol ing
co osion phenomena ha accompany pi o ma ion—o en missed wi h a i icial pi s— his s udy acks he en i e
sequence om pi o ma ion and g ow h h ough c ack nuclea ion and ea ly p opaga ion o iden i y a a ional
ini ia ion c i e ion (Nc).
To ensu e he s uc u al eliabili y o s eel componen s and o enable mo e a ional a igue design, i is essen ial
o es ablish a gene alized c i e ion o co osion a igue c ack ini ia ion li e (Nc). In his s udy, a gene alized
de ini ion o Nc is p oposed o c acks ini ia ed om small co osion pi s, ep esen ing he pi - o-c ack ansi ion.
The alidi y and a ionali y o his de ini ion a e examined h ough bo h expe imen al in es iga ion and
heo e ical analysis. Speci ically, co osion a igue c ack ini ia ion es s we e conduc ed in a 3% NaCl aqueous
solu ion using a 13C s ainless s eel (SUS410J1), and he esul s we e e alua ed using a ac u e mechanics-based
analysis inco po a ing an in insic c ack model[14].
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2. P oposal o he Assessmen o Co osion Fa igue C ack Ini ia ion Li e (Nc)
2.1. Co osion Fa igue C ack Ini ia ion and P opaga ion Model
The co osion a igue c ack ini ia ion and p opaga ion model p oposed in his s udy is shown in Figu e 1 [15].
In his model, co osion pi s a e ega ded as p ecu so s o s uc u al ailu e. The co osion a igue c ack ini ia ion
li e (Nc) is de ined as he poin whe e a a igue c ack ini ia es and begins o p opaga e om he base o a g owing
co osion pi , a a a e exceeding he g ow h a e o he pi . As illus a ed in Figu e 1, he co osion a igue c ack
ini ia ion and p opaga ion p ocess can be classi ied in o he ollowing dis inc s ages.
① Co osion pi ini ia ion/g ow h.
② Co osion a igue c ack ini ia es by he s ess concen a ion o he co osion pi .
③ Co osion pi g ow h speed is as e han he co osion a igue c ack.
④ Co osion a igue c ack p opaga ion speed is equal o he co osion pi g ow h speed.
Fa igue c ack p opaga es in ea nes .
⑤ Co osion a igue c ack p opaga es. Co osion a igue c ack p opaga ion speed su passes co osion pi
g ow h speed.
⑥ F ac u e.
Figu e 1. P oposed co osion a igue c ack ini ia ion and p opaga ion model, illus a ing six sequen ial s ages
om pi o ma ion o inal ac u e (①–⑥). De ailed desc ip ions o each s age a e p o ided in Sec ion 2.
The poin a which a igue c acks ini ia e and p opaga e om he base o g owing co osion pi s is de ined as
he co osion a igue c ack ini ia ion li e (Nc) [15]. In he p esen s udy, Nc is speci ically de ined as he poin
co esponding o s age ④, as desc ibed abo e. The objec i e o his s udy is o e i y he alidi y o he p oposed
Nc h ough bo h expe imen al in es iga ion and heo e ical analysis. A lowcha o p edic ing co osion a igue
li e based on he p oposed model illus a ed in Figu e 1 is p esen ed in Figu e 2.
This lowcha ou lines he p ocedu e o iden i ying and e alua ing he ini ia ion and g ow h beha io o
co osion pi s, which a e in luenced by ma e ial p ope ies, co osi e en i onmen , and loading condi ions. In
pa allel, he co osion pi is modeled as a small c ack o calcula e i s s ess in ensi y ac o ange (ΔK), allowing
o he assessmen o he c i ical condi ion o co osion a igue c ack ini ia ion.
I he calcula ed ΔK o he co osion pi is lowe han he h eshold s ess in ensi y ac o ange (ΔK h), c ack
ini ia ion does no occu . Con e sely, when ΔK exceeds ΔK h, a co osion a igue c ack is conside ed o ha e
ini ia ed and o p opaga e isibly. The p opaga ion a e o he co osion a igue c ack o igina ing om he pi is
hen de e mined and compa ed wi h he pi g ow h a e. I he pi g ow h a e exceeds he c ack p opaga ion a e,
he co osion a igue c ack is ega ded as no ye ini ia ed.
Once he de ini ion o Nc, as s a ed abo e, is sa is ied, he co osion a igue c ack p opaga ion beha io is
e alua ed o he in e al om Nc o he inal ac u e li e (N ). The o al a igue li e (N ) is hus de e mined by
combining he e alua ion o co osion pi ini ia ion and g ow h wi h ha o co osion a igue c ack ini ia ion and
p opaga ion. Fu he mo e, o de e mine Nc, he c i ical pi dimensions mus be assessed by applying linea elas ic
ac u e mechanics o small-scale c acks. In his s udy, an analysis was conduc ed on hese aspec s, and he esul s
a e p esen ed sequen ially in he ollowing sec ions.
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Figu e 2. Flow cha o co osion a igue ini ia ion li e p edic ion.
2.2. Concep o In insic C ack Model
C acks nea he co osion pi s o co osion a igue c ack ini ia ion li e (Nc) a e e y small in size and he e o e
need o be ea ed as small c acks. I is well known ha con en ional ac u e mechanics canno be di ec ly applied
o small c acks [16]. In his s udy, o e alua e he co osion a igue c ack ini ia ion li e (Nc) in a easonable manne ,
a simple and p ac ical in insic c ack model [14] conside ing he p esence o la en c ack was in oduced. Using
his model, he co osion a igue c ack ini ia ion li e (Nc) was e alua ed using a ac u e mechanics me hod
conside ing he in luence o small c acks. Mo i a e al. applied his model o (1) ound-shaped mac o laws, (2)
small laws, (3) clus e ed small laws, and (4) mac o c acks.
In his s udy, he in insic c ack model (ICM) was applied o es ima e he co osion- a igue c ack ini ia ion li e.
This choice was mo i a ed by he expec a ion ha he ICM would enable a quan i a i e and uni ied e alua ion o
co osion a igue o e he en i e li e cycle, om ini ia ion o p opaga ion, ac oss he small and long c ack egimes.
The concep o he in insic c ack model is as ollows. In con en ional linea ac u e mechanics, when
conside ing a c ack pene a ing he ou e su ace o a semi-in ini e pla e, he a igue limi o a c acked pla e △σ h
is de e mined as ollows.
∆ = 1.12∆√ = ∆
om which
∆ = ∆/(1.12√)
(1)
As shown in Figu e 3, he ela ionship be ween he a igue limi △σ h o a c acked ma e ial, as gi en in equa ion
(1) and he c ack leng h a is such ha △σ h becomes in ini e as he c ack leng h a app oaches ze o. Howe e , △σ h
canno be g ea e han he a igue limi △σw0 o a smoo h ma e ial. The e o e, o de e mine he a igue limi o a
de ec - ee smoo h ma e ial om a ac u e mechanics pe spec i e, i is assumed ha ma e ial-in insic po en ial
c acks exis in bo h he smoo h ma e ial and he c acked ma e ial, and hese a e e e ed o as in insic c acks as
illus a ed in Figu e 4. In a c acked ma e ial, he c ack leng h is ep esen ed as he sum o he ac ual c ack leng h
and he in insic c ack leng h. The leng h o he in insic c ack, a0, can be exp essed using he ollowing equa ion
(2) based on he a igue limi o he smoo h pla e and he h eshold s ess in ensi y ac o ange (△K h).
= (1/)[∆/(1.12∆)]
(2)
whe e △σw0 is a igue limi o smoo h pla e
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Figu e 3. Concep o in insic c ack leng h a0
(a) a plane body (b) a c acked body
Figu e 4. Concep o in insic c ack leng h a0 a plane body and a c acked body
3. Co osion Fa igue C ack Ini ia ion Tes
To alida e he co osion a igue c ack ini ia ion and p opaga ion model illus a ed in Figu e 1, a igue es s
we e pe o med in a co osi e en i onmen using a 3% NaCl aqueous solu ion. The aim o hese expe imen s was
o obse e and cha ac e ize he ini ia ion and g ow h o co osion pi s, as well as he ini ia ion and p opaga ion o
co osion a igue c acks. Fo di ec obse a ion o hese p ocess, in-si u isual moni o ing wi h a po able
mic oscope was conduc ed du ing es ing. Addi ionally, each specimen was examined mul iple imes using bo h a
s e eomic oscope and a me allu gical mic oscope o mo e de ailed analysis. A e inal ac u e, he ac u e
su aces we e also obse ed unde a mic oscope o ob ain aluable in o ma ion ele an o he s udy objec i es.
3.1. Ma e ials, Specimens, and Expe imen al Me hods
Al hough olled s eels, such as hose used in la ge-scale ma ine s uc u es, a e desi able as es ma e ials o
co osion a igue c ack ini ia ion s udies, hey a e expec ed o unde go gene al co osion in a seawa e en i onmen
[17,18], making he obse a ion and e alua ion o co osion pi and co osion a igue c ack beha io ex emely
di icul . In he p esen s udy, he aim was o in es iga e he ini ia ion and g ow h o co osion pi s, oge he wi h
he ini ia ion and p opaga ion o co osion a igue c acks. Fo his pu pose, a 13C -based s ainless s eel (SUS410J1)
was selec ed, as i can be used in seawa e en i onmen s wi hou unde going gene al co osion, he eby acili a ing
he obse a ion o localized pi ing. This ma e ial has been used o u bine blades, and mo e ecen ly i has also
been conside ed o applica ions in ma ine s uc u es such as ise s [3].
The chemical composi ion and mechanical p ope ies o he ma e ial a e gi en in Table 1 and Table 2,
espec i ely.
Table 1. Chemical composi ion o ma e ial used
C
Si
Mn
P
S
Ni
C
Mo
0.13
0.32
0.51
0.024
0.002
0.55
11.99
0.36
(w %)
Table 2. Mechanical p ope ies o ma e ial used
Y.P.(kg /mm2)
T.S.(kg /mm2)
El.(%)
R.A.(%)
H
61.6
75.4
23.8
68.7
223
0.01 0.1 1 10 100
C ack Leng h a (mm)
0
20
40
60
80
Th eshold S ess Range
a0
△σW0
LEFM
△σ h (mm)
,
,
6
Two specimens we e ab ica ed om he selec ed ma e ial and used o es ing. These we e designa ed as
Specimen No. 1 and Specimen No. 2, espec i ely, and hei geome ies a e illus a ed in Figu e 5. Bo h specimens
we e p epa ed wi hou no ch machining and used as smoo h specimens. The su aces o he specimens we e
inished using #1600 eme y pape . Addi ionally, o acili a e he obse a ion o co osion pi s, he gauge sec ion
o each specimen was de ined by applying a masking ea men . To p e en a igue c ack ini ia ion om he edges
o he specimen and o ensu e adequa e adhesion o he masking ilm, he ou co ne s o he pa allel sec ion o
he specimens we e cham e ed. The masking was applied in wo laye s using K.T. Clean AC818T and K.T. Clean
AC832T, wi h each coa ing applied h ee imes in o al along bo h he longi udinal and ans e se di ec ions o he
specimens. The masking condi ions o Specimen No. 1 and Specimen No. 2 a e shown in Figu e 6.
In addi ion, o Specimen No. 2, a anspa en plas ic pla e was a ached o he obse a ion a ea o p omo e
c e ice co osion in en ionally. Figu e 7 illus a es he masking con igu a ion and a schema ic ep esen a ion o
he c e ice co osion condi ion o Specimen No. 2.
Figu e 5. Shape o co osion a igue ini ia ion es specimen.
F on iew o Specimen No. 1
Figu e 6. View o masked Specimens No. 1 and No. 2.
F on iew o Specimen No. 1
Obse ing a ea o Specimen No. 1
Condi ion o c e ice co osion o Specimen No. 1
7
Figu e 7. C e ice co osion and masking con igu a ion o Specimen No. 2.
Table 3. Chemical composi ion o ma e ial used
Maximum load
No.1
4.7 on
No.2
3.6 on
S ess a io
0.1
Tes equency
1.7 Hz
Tempe a u e
60 ℃
En i onmen
3% NaCl solu ion
A uniaxial, i e-link elec o-hyd aulic a igue es ing machine wi h a load capaci y o 10 on was employed
o he co osion a igue c ack ini ia ion es s. The es condi ions a e summa ized in Table 3. The maximum load
was se o 4.7 on , co esponding o a maximum s ess o 59.4 kg /mm², o Specimen No. 1, and 3.6 on (57.0
kg /mm²) o Specimen No. 2. All es s we e conduc ed unde axial ension-comp ession loading wi h a s ess a io
o 0.1 and a loading equency o 1.7 Hz. A 3% NaCl aqueous solu ion was used as he co osi e en i onmen ,
main ained a a empe a u e o 60 ℃ and sa u a ed wi h ai h ough con inuous ae a ion.
The solu ion was eplaced wi h esh elec oly e once pe week. The solu ion was ci cula ed using he sys em
schema ically illus a ed in Figu e 8. The size o he co osion solu ion ank was de e mined based on he
specimen's dimensions and ab ica ed om ac ylic esin pla es, allowing easy isual obse a ion wi h a po able
mic oscope. Addi ionally, o acili a e apid obse a ion when di ec isual moni o ing was imp ac ical, he ank
was designed o be de achable a i s in e ace wi h he specimen. The specimen was also elec ically insula ed o
p e en unin ended cu en low. To achie e his, he jig was coa ed wi h an insula ing laye and equipped wi h a
Te lon sea . An insula ing gaske was inse ed be ween he jig and he es ing machine, and insula ing washe s
we e used in he bol ed connec ions.
Fu he mo e, he pin was w apped in a glass ibe ube, which was coa ed wi h g ease o enhance insula ion.
Figu e 9 p esen s he expe imen al iew. Fu he mo e, o Specimens No. 1 and No. 2, in o de o ace he
co osion a igue c ack p opaga ion p ocess, beachma ks we e in oduced on he ac u e su ace by applying
cyclic loading co esponding o a s ess a io o app oxima ely 0.9. Beachma ks we e c ea ed h ough cyclic
loading o abou 3 × 10³ o 2 × 10⁴ cycles o Specimens No. 1 and No. 2.
Figu e 8. Co osion a igue c ack ini ia ion es appa a us.
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Figu e 9. Expe imen al se up o co osion a igue c ack ini ia ion es .
3.2. Ma e ials, Specimens, and Expe imen al Me hods
The a igue li e (N ) o Specimen No. 1 and No. 2 was 1.48 × 10⁵ cycles and 1.35 × 10⁶ cycles, espec i ely.
The obse a ion esul s o Specimen No. 1 and No. 2 a e p esen ed as ollows.
3.2.1. Obse a ion Resul s o Specimen No. 1 (wi hou c e ice co osion condi ion)
The obse a ion esul s o Specimen No. 1 a e p esen ed in Table 4 and Figu e 10. The de ailed obse a ions
a e desc ibed below in he o de o he numbe ing in Table 4.
<1> A newly o med co osion pi was disco e ed nea he si e whe e c e ice co osion had occu ed.
<2> The co osion pi con inued o g ow.
<3> I was obse ed ha c acks we e p opaga ing om bo h ends o he co osion pi . A his s age,
beachma king was pe o med o he i s ime by applying cyclic loading o 4.2–4.7 on a 10,000 cycles.
<4> -
<5> The second beachma k was in oduced by applying cyclic loading o 4.2–4.7 on a 5,000 cycles.
<6> -
<7> -
<8> The specimen ac u ed.
The ac u e condi ion o Specimen No. 1 is shown in Figu e 11. On he ac u e su ace, a co osion pi wi h
a diame e (su ace leng h 2c) o 0.27 mm and a dep h o 0.19 mm was p esen a he c ack ini ia ion si e. I was
con i med ha he co osion a igue c ack ini ia ed om his co osion pi and p og essed o inal ac u e.
Table 4. Obse a ion esul s o Specimen No.1
Obse a ion
No.
Numbe o cycles,
N(cycles)
△N(cycles)
c(mm)
Rema k
<1>
105,620
-
0.11 *
Co osion pi
<2>
112,640
7,020
0.12 *
Co osion pi
<3>
121,820
9,180
0.24 **
C ack begin o p opaga e,
1s beachma k
<4>
127,450
5,630
0.60 **
-
<5>
130,200
2,750
1.53 *
2nd beachma k
<6>
131,090
890
2.42 *
-
<7>
131,900
810
2.91 *
-
<8>
132,990
1,090
3.73 **
F ac u ed
N does no include beachma k pe iod
2c: diame e o co osion pi / leng h o co osion a igue c ack
* : measu ed by a elling mic oscope
**: measu ed by measu ing mic oscope
9
<3> C ack a e he i s beachma k, N=121,820 cycles (Specimen No. 1)
<5> C ack a e he second beachma k, N=130,200 cycles (Specimen No. 1)
Figu e 10. Obse a ion esul s o Specimen No.1.
Figu e 11. Condi ion o ac u e and ac u e su ace o Specimen No.1.
F on iew o Specimen No. 1
F ac u e su ace 1
Co osion pi o a igue c ack ini ia ion si e
16
[8] B.M. Schönbaue , S.E. S anzl-Tschegg, A. Pe lega, R.N. Salzman, N.F. Riege , S. Zhou, A. Tu nbull and D. Gandy. The
in luence o co osion pi s on he a igue li e o 17-4PH s eam u bine blade s eel. Enginee ing F ac u e Mechanics,
147:158-175, 2015.
[9] J.R. Donahue and J.T. Bu ns. E ec o chlo ide concen a ion on he co osion– a igue c ack beha io o an age-
ha denable ma ensi ic s ainless s eel. In e na ional Jou nal o Fa igue, 91:79-99, 2016.
[10] J.R. Donahue, A.B. Lass and J.T. Bu ns. The in e ac ion o co osion a igue and s ess-co osion c acking in a
p ecipi a ion-ha dened ma ensi ic s ainless s eel. npj Ma e ials Deg ada ion, 1:11, 2017.
[11] N.O. La osa, R. Akid and R.A. Ainswo h. Co osion- a igue: a e iew o damage ole ance models. In e na ional
Ma e ials Re iews, 63(5):283-308, 2018.
[12] J.A. Balbín, V. Cha es and N.O. La osa. Pi o c ack ansi ion and co osion a igue li e ime educ ion es ima ions by
means o a sho c ack mic os uc u al model. Co osion Science, 180:109171, 2021.
[13] R.P. Ganglo . Co osion Fa igue C ack P opaga ion in Me als. NASA Con ac o Repo CR-4301. NASA, Washing on,
DC, USA, 1990.
[14] K. Mo i a, K. Kajimo o, R. Mu ai, M. Fujii, M. Shimogouchi and M. Iwa a. E ec o laws on a igue s eng h o cas o
o ged ma e ial. Mi subishi Hea y Indus ies Technical Re iew, 30(3):270-275, 1993.
[15] W.B. Kim, J.K. Paik and H. Yajima. E alua ion o co osion a igue c ack ini ia ion li e o 13C s eel. Key Enginee ing
Ma e ials, 326-328:1007-1010, 2006.
[16] La sen, J.M., Allison, J.E. (Eds.). Small-C ack Tes Me hods. ASTM Special Technical Publica ion 1149, Ame ican
Socie y o Tes ing and Ma e ials, Philadelphia, PA. ISBN 0-8031-1469-9, 1992.
[17] W.B. Kim, J.K. Paik, M. Iwa a and H. Yajima. Fa igue s eng h o us ing decayed hull s eel pla e in ai and a i icial
seawa e condi ion. Jou nal o he Socie y o Na al A chi ec s o Ko ea, 40(1):63–68, 2006.
[18] W.B. Kim. E alua ion o long- e m co osion a igue li e o ship and o sho e s uc u al s eel. In T. Okada, K. Suzuki
and Y. Kawamu a, edi o s, P ac ical Design o Ships and O he Floa ing S uc u es, PRADS 2019. Lec u e No es in
Ci il Enginee ing, ol. 64, pages 406–416. Sp inge , Singapo e, 2021. h ps://doi.o g/10.1007/978-981-15-4672-3_32
[19] Engelha d , G., Macdonald, D. Co osion o Low P essu e S eam Tu bine Componen s. In e im Repo 1000557, Elec ic
Powe Resea ch Ins i u e (EPRI), Palo Al o, CA., 2000.
[20] L.-B. Niu, H. Ka o, K. Shiokawa, K. Nakamu a, M. Yamashi a and Y. Sakai. Elec ochemical c e ice co osion beha io s
o low-p essu e s eam u bine ma e ials in he simula ed boile wa e added chlo ide and sul a e ions. Ma e ials
T ansac ions, 54(12):2225–2232, 2013. h ps://doi.o g/10.2320/ma e ans.M2013202
[21] M. Tachibana, K. Ishida, Y. Wada, N. O a and N. Shigenaka. E ec s o gamma- ay i adia ion on c e ice co osion
epassi a ion po en ial o s ainless s eel in high empe a u e dilu ed simula ed seawa e . Jou nal o Nuclea Science and
Technology, 53(7):981–991, 2016. h ps://doi.o g/10.1080/00223131.2015.1085814
[22] M. Rincón O íz, M.A. Rod íguez, R.M. Ca anza and R.B. Rebak. De e mina ion o he c e ice co osion s abiliza ion
and epassi a ion po en ials o a co osion- esis an alloy. Co osion, 66(10):105002, 2010.
h ps://doi.o g/10.5006/1.3500830
[23] K. Nose, K. Miyamo o and T. Yoshinobu. Es ima ion o po en ial dis ibu ion du ing c e ice co osion h ough analysis
o I–V cu es ob ained by LAPS. Senso s, 20(10):2873, 2020. h ps://doi.o g/10.3390/s20102873
[24] Mi subishi Hea y Indus ies, L d., Technical Headqua e s, Nagasaki Resea ch & De elopmen Cen e , In e nal Repo
1979.
[25] J.C. Newman and I.S. Raju. S ess-In ensi y Fac o Equa ions o C acks in Th ee-Dimensional Fini e Bodies. NASA
Technical Memo andum 83200, 1981.
[26] K. Tanaka. The P opaga ion o Small Fa igue C acks, Zai you, Vol. 33, No. 371. 961-972, 1989.
[27] R. Eba a, T. Tamada and H. Kawano. Co osion a igue p ocess o 12C s ainless s eel. ISIJ In e na ional, 30(7), 535–
539, 1990.
