Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting
This work is aimed to assess the fatigue strength of Ti–6Al–4V smooth and circular notched samples produced by selective laser melting (SLM). Scanning electron microscopy have been used to investigate the fracture surface of the broken samples in order to identify crack initiation points and fractur...
Gespeichert in:
| Datum: | 2017 |
|---|---|
| Hauptverfasser: | , , |
| Format: | Artikel |
| Sprache: | English |
| Veröffentlicht: |
Інститут проблем міцності ім. Г.С. Писаренко НАН України
2017
|
| Schriftenreihe: | Проблемы прочности |
| Schlagworte: | |
| Online Zugang: | https://nasplib.isofts.kiev.ua/handle/123456789/173676 |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Zitieren: | Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting / S.M.J. Razavi, P. Ferro, F. Berto // Проблемы прочности. — 2017. — № 3. — С. 105-114. — Бібліогр.: 20 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-173676 |
|---|---|
| record_format |
dspace |
| spelling |
nasplib_isofts_kiev_ua-123456789-1736762025-02-09T14:29:34Z Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting Утомна міцність плоских зразків із двосторонніми напівкруглими вирізами зі сплаву ТІ-6А1-4V, виготовлених за технологією вибірної лазерної плавки Razavi, S.M.J. Ferro, P. Berto, F. Научно-технический раздел This work is aimed to assess the fatigue strength of Ti–6Al–4V smooth and circular notched samples produced by selective laser melting (SLM). Scanning electron microscopy have been used to investigate the fracture surface of the broken samples in order to identify crack initiation points and fracture mechanisms. Despite the observed fatigue strength reduction induced by circular notch compared to that of sooth specimens, notched samples showed a very low notch sensitivity attributed both to hexagonal crystal lattice characteristics of tempered alpha prime grains and to surface defects induced by the SLM process itself. Досліджується міцність від утомленості плоских зразків (гладкі і з двосторонніми напівкруглими вирізами) зі сплаву Ті–6Al–4V, які виготовлено за технологією вибірної лазерної плавки. Для ідентифікації місця зародження тріщини від утомленості та механізму руйнування фрактограми зруйнованих зразків досліджувались методом сканувальної електронної мікроскопії. Установлено, що міцність від утомленості зразків із концентратором напружень у вигляді двосторонніх напівкруглих вирізів трохи нижча, аніж гладких зразків. Показано, що чутливість даного матеріалу до концентрації напружень дуже низька через специфіку гексагональної кристалічної решітки загартованих первинних альфа-зерен і технологічних поверхневих дефектів, характерних для вибірної лазерної плавки. Исследуется усталостная прочность плоских образцов (гладкие и с двухсторонними полукруглыми вырезами) из сплава Ti–6Al–4V, изготовленных по технологии избирательной лазерной плавки. Для идентификации мест зарождения усталостной трещины и механизма разрушения фрактограммы разрушенных образцов исследовались методом сканирующей электронной микроскопии. Установлено, что усталостная прочность образцов с концентратором напряжений в виде двухсторонних полукруглых вырезов незначительно ниже, чем гладких образцов. Показано, что чувствительность данного материала к концентрации напряжений очень низкая из-за специфики гексагональной кристаллической решетки закаленных первичных альфа-зерен и технологических поверхностных дефектов, характерных для избирательной лазерной плавки. 2017 Article Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting / S.M.J. Razavi, P. Ferro, F. Berto // Проблемы прочности. — 2017. — № 3. — С. 105-114. — Бібліогр.: 20 назв. — англ. 0556-171X https://nasplib.isofts.kiev.ua/handle/123456789/173676 539.4 en Проблемы прочности application/pdf Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| topic |
Научно-технический раздел Научно-технический раздел |
| spellingShingle |
Научно-технический раздел Научно-технический раздел Razavi, S.M.J. Ferro, P. Berto, F. Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting Проблемы прочности |
| description |
This work is aimed to assess the fatigue strength of Ti–6Al–4V smooth and circular notched samples produced by selective laser melting (SLM). Scanning electron microscopy have been used to investigate the fracture surface of the broken samples in order to identify crack initiation points and fracture mechanisms. Despite the observed fatigue strength reduction induced by circular notch compared to that of sooth specimens, notched samples showed a very low notch sensitivity attributed both to hexagonal crystal lattice characteristics of tempered alpha prime grains and to surface defects induced by the SLM process itself. |
| format |
Article |
| author |
Razavi, S.M.J. Ferro, P. Berto, F. |
| author_facet |
Razavi, S.M.J. Ferro, P. Berto, F. |
| author_sort |
Razavi, S.M.J. |
| title |
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting |
| title_short |
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting |
| title_full |
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting |
| title_fullStr |
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting |
| title_full_unstemmed |
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting |
| title_sort |
fatigue assessment of ti–6al–4v circular notched specimens produced by selective laser melting |
| publisher |
Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| publishDate |
2017 |
| topic_facet |
Научно-технический раздел |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/173676 |
| citation_txt |
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by Selective Laser Melting / S.M.J. Razavi, P. Ferro, F. Berto // Проблемы прочности. — 2017. — № 3. — С. 105-114. — Бібліогр.: 20 назв. — англ. |
| series |
Проблемы прочности |
| work_keys_str_mv |
AT razavismj fatigueassessmentofti6al4vcircularnotchedspecimensproducedbyselectivelasermelting AT ferrop fatigueassessmentofti6al4vcircularnotchedspecimensproducedbyselectivelasermelting AT bertof fatigueassessmentofti6al4vcircularnotchedspecimensproducedbyselectivelasermelting AT razavismj utomnamícnístʹploskihzrazkívízdvostoronníminapívkruglimivirízamizísplavutí6a14vvigotovlenihzatehnologíêûvibírnoílazernoíplavki AT ferrop utomnamícnístʹploskihzrazkívízdvostoronníminapívkruglimivirízamizísplavutí6a14vvigotovlenihzatehnologíêûvibírnoílazernoíplavki AT bertof utomnamícnístʹploskihzrazkívízdvostoronníminapívkruglimivirízamizísplavutí6a14vvigotovlenihzatehnologíêûvibírnoílazernoíplavki |
| first_indexed |
2025-11-26T20:33:30Z |
| last_indexed |
2025-11-26T20:33:30Z |
| _version_ |
1849886468816764928 |
| fulltext |
UDC 539.4
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens Produced by
Selective Laser Melting
S. M. J. Razavi,
a
P. Ferro,
b
and F. Berto
a,1
a Department of Mechanical and Industrial Engineering, Norwegian University of Science and
Technology (NTNU), Trondheim, Norway
b Department of Engineering and Management, University of Padova, Vicenza, Italy
1 filippo.berto@ntnu.no
ÓÄÊ 539.4
Óòîìíà ì³öí³ñòü ïëîñêèõ çðàçê³â ³ç äâîñòîðîíí³ìè íàï³âêðóãëèìè âèð³çàìè
ç³ ñïëàâó Ti–6Al–4V, âèãîòîâëåíèõ çà òåõíîëî㳺þ âèá³ðíî¿ ëàçåðíî¿ ïëàâêè
Ñ. Ì. Äæ. Ðàçàâè
à
, Ï. Ôåððî
á
, Ô. Áåðòî
à
à Ìåõàí³êî-ìàøèíîáóä³âíèé ôàêóëüòåò, Íîðâåæñüêèé óí³âåðñèòåò ïðèðîäíèõ ³ òåõí³÷íèõ íàóê,
Òðîíõåéì, Íîðâåã³ÿ
á Ôàêóëüòåò ìåíåäæìåíòà òà ³íæ³í³ð³íãà, Ïàäóàíñüêèé óí³âåðñèòåò, ³÷åíöà, ²òàë³ÿ
Ñïåö³àëüí³ òåõíîëî㳿 âèðîáíèöòâà äîçâîëÿþòü åêîíîì³÷íî îá´ðóíòîâàíî âèãîòîâëÿòè äåòàë³
ñêëàäíî¿ êîíô³ãóðàö³¿ ç ì³í³ì³çàö³ºþ öèêëó â³ä ðîçðîáêè äî âèðîáíèöòâà. Äëÿ âèêîðèñòàííÿ ö³º¿
òåõíîëî㳿 äî âèñîêîíàâàíòàæåíèõ â³äïîâ³äàëüíèõ åëåìåíò³â êîíñòðóêö³é íåîáõ³äíî âèâ÷èòè
ñïåöèô³êó ¿¿ âïëèâó íà õàðàêòåðèñòèêè óòîìè îòðèìàíèõ ìàòåð³àë³â íà ì³êðî-, ìàêðî- ³ ìåçî-
ð³âí³. Äîñë³äæóºòüñÿ ì³öí³ñòü â³ä óòîìëåíîñò³ ïëîñêèõ çðàçê³â (ãëàäê³ ³ ç äâîñòîðîíí³ìè
íàï³âêðóãëèìè âèð³çàìè) ç³ ñïëàâó Ò³–6Al–4V, ÿê³ âèãîòîâëåíî çà òåõíîëî㳺þ âèá³ðíî¿ ëàçåðíî¿
ïëàâêè. Äëÿ ³äåíòèô³êàö³¿ ì³ñöÿ çàðîäæåííÿ òð³ùèíè â³ä óòîìëåíîñò³ òà ìåõàí³çìó ðóéíó-
âàííÿ ôðàêòîãðàìè çðóéíîâàíèõ çðàçê³â äîñë³äæóâàëèñü ìåòîäîì ñêàíóâàëüíî¿ åëåêòðîííî¿
ì³êðîñêîﳿ. Óñòàíîâëåíî, ùî ì³öí³ñòü â³ä óòîìëåíîñò³ çðàçê³â ³ç êîíöåíòðàòîðîì íàïðó-
æåíü ó âèãëÿä³ äâîñòîðîíí³õ íàï³âêðóãëèõ âèð³ç³â òðîõè íèæ÷à, àí³æ ãëàäêèõ çðàçê³â. Ïîêà-
çàíî, ùî ÷óòëèâ³ñòü äàíîãî ìàòåð³àëó äî êîíöåíòðàö³¿ íàïðóæåíü äóæå íèçüêà ÷åðåç ñïåöè-
ô³êó ãåêñàãîíàëüíî¿ êðèñòàë³÷íî¿ ðåø³òêè çàãàðòîâàíèõ ïåðâèííèõ àëüôà-çåðåí ³ òåõíîëî-
ã³÷íèõ ïîâåðõíåâèõ äåôåêò³â, õàðàêòåðíèõ äëÿ âèá³ðíî¿ ëàçåðíî¿ ïëàâêè.
Êëþ÷îâ³ ñëîâà: ñïåö³àëüí³ òåõíîëî㳿 âèðîáíèöòâà, íàï³âêðóãëèé âèð³ç, óòîìà, âèá³ðíà
ëàçåðíà ïëàâêà.
Introduction. Additive manufacturing (AM) is a process that allows a part to be built
layer-by-layer by using a combination of energy delivery and material deposition. Metallic
parts are obtained starting from powders that are melted by a laser or electron beam source.
This results in a high sensitivity of material properties to process parameters. According to
source parameters, the material can experience different thermal histories and thus different
microstructures [1–4]. The microstructure of AM parts can be highly anisotropic and can
reach a density greater than 99.5% [5, 6]. For example, columnar grains are shown to grow
epitaxially through the deposition layers due to cooling [5].
Compared to traditional shaping processes, AM offers different advantages such as a
shorter time-to market, a near-net-shape fabrication without the need of expensive moulds
and tools, a high efficiency in material utilization, the possibility to directly produce
© S. M. J. RAZAVi, P. FERRO, F. BERTO, 2017
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3 105
geometries with high level of flexibility based on CAD models. On the other hand, AM
parts suffer the presence of defects often related to non-optimal scan parameters (unmolten
particles, spherical entrapped gas bubbles, lack of fusion) [7]. Among the AM processes, a
particular attention is paid on selective laser melting (SLM), a powder bed fusion-laser
(PBF-L) method [8, 9]. The possibility to create structures with complex geometries out of
high performance materials has made SLM particularly interesting for aerospace and
biomedical industry, where titanium alloys, and in particular Ti–6Al–4V, are widely used.
Titanium alloys are in fact characterized by excellent corrosion resistance, high specific
strength, low density and low elastic modulus.
Both in aerospace and biomedical applications, fatigue is the primary mechanism of
rupture in components such as turbine blade, hip prosthesis and mechanical heart valve
[10–12]. For this reason, the fatigue strength of additive manufactured parts is widely
studied in literature. In their work about high cycle fatigue (HCF) behavior of SLM-
processed Ti–6Al–4V, Leuders et al. [13] found that porosity acts as strong stress raiser and
lead to failure. In order to improve the fatigue strength of titanium alloy Ti–6Al–4V
manufactured by SLM, reduction of porosity was thus considered by authors much more
important than microstructure optimization. In a more recent work [14], Kasperovich and
Hausmann found a reduction in fatigue resistance of SLM processed TiAl6V4 compared to
the wrought alloy due to a combination of the unfavourable martensitic microstructure,
unmolten particles, pores, and microcracks. Finally, they found that in order to restore the
fatigue resistance of the conventionally processed TiAl6V4, SLM-processed, specimens
need to be subjected to hot isostatic pressing (HIP), which reduces porosity, and surface
machining which reduces surface roughness. As a matter of fact, for AM parts that cannot
be machined on all surfaces, the rough ‘as built’ surface should be considered as crack
initiator in the fatigue design process leading to their lower fatigue strength. Finally, in that
work, heat treatments were found to give no significant improvement on HCF strength.
Due to some specific design requirements such as connecting different parts together
and repairing cracked or damaged structures, the majority of engineering components and
structures contain notches of different shapes. By their utility, notches are prone to crack
nucleation due to the intensified stress at their neighbourhood. Nucleated cracks may
propagate and lead to final failure of the notched component. Hence, it is commonly
attempted in design of notched components to prevent or delay the crack nucleation from
the notch edge [15–19]. For this aim, failure mechanisms in presence of notches should be
deeply studied.
Examination of the state-of-the-art shows that fatigue assessment and quality assurance
of additively manufactured components cannot be performed accurately due to a lack of
bespoke methodologies allowing the specific microstructural features as well as the specific
mechanical/cracking behavior of additively manufactured materials to be modelled
effectively. Therefore, owing to the growing importance of additive manufacturing
technologies, fundamental theoretical understanding of fatigue properties and behavior of
additively manufactured metals is a necessary step that must be taken as a matter of
urgency. In this challenging scenario, the problem is complicated by the fact that, as far as
components having complex geometries are concerned, no specific design criteria have
been proposed so far to take into account stress concentration phenomena arising from
geometrical discontinuities/features (here termed notches). Further, no fatigue data generated
by testing additively manufactured notched metals can be found in the technical literature.
This lack of specific knowledge makes it difficult for industry to take full advantage of the
unique features of adittive manufacturing, with this preventing this powerful technology
from being injected effectively into every-day manufacturing practises. In this context, this
work aims to contribute to the fundamental understanding of the mechanical/cracking
behavior of additively manufactured Ti–6Al–4V specimens weakened by circular notches
and subjected to fatigue loading.
S. M. J. Razavi, P. Ferro, and F. Berto
106 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3
1. Material, Geometries, and Experimental Procedure. The analyzed Ti–6Al–4V
specimens were produced by means of SLM by using optimized process parameters that
guaranteed a density greater than 99.7%. After specimens’ production, specimens were
sandblasted at 6 bar using corundum sand with a mean grain size of 220 �m. They were
then stress relief heat-treated in non-controlled atmosphere (heating rate: 10.8 �C/min;
holding time: 3h at 650�C; cooling rate: 2 �C/min) and after cutting off the base plate they
were re-sandblasted at 6 bar using corundum sand. All specimens were obtained by using a
layer thickness of 60 �m. Figure 1 shows the geometries of smooth and circular notched
specimens. The radius at the notch is 5 mm while the thickness of the specimens is 3 mm.
Fatigue tests were carried out by using a universal MTS machine (250 kN). All tests
have been carried out under load control, using a sinusoidal signal in uniaxial tension with
a frequency of 10 Hz and load ratio R � 0. The run out limit was set equal to 106 cycles.
The microstructure and the fracture surface of the specimens were investigated by optical
microscope (OM) and environmental scanning electron microscope (ESEM) (FEI
QUANTA 400), respectively.
Kroll’s Reagent (2 ml HF, 2 ml HNO3, 100 ml H2O) was used as metallographic
etchant. The alpha prime and acicular alpha structures of titanium alloy will appear white
after etching while intergranular beta structure and beta grains will be darkened.
A numerical model under plain stress condition was carried out using ANSYS®
numerical code, in order to calculate the stress concentration factor, K t . The Young
modulus and Poisson’s ratio were set equal to 110 GPa and 0.34, respectively. By taking
advantage of the double symmetry, only one fourth of the specimen was modelled by using
a mapped mesh (Fig. 2a). Figure 2b shows the principal stress distribution induced by a
remotely applied tension (� n ) of 213 MPa.
2. Results.
2.1. Fatigue Test Results. Results obtained from the statistical elaboration of fatigue
tests data for smooth and notched specimens are reported in Figs. 3 and 4, respectively.
Values of stress amplitude related to a survival probability of 50%, the slope of the Wöhler
curve and the scatter index T� (the ratio between the stress amplitudes corresponding to 10
and 90% of survival probability) are reported in the above figures. Specimens survived
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens ...
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3 107
Fig. 1. Geometries of smooth and circular notched specimens and built axis (Z) (dimensions in mm).
108 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3
S. M. J. Razavi, P. Ferro, and F. Berto
a b
Fig. 2. Mesh of the specimen with a double circular notch (a) and principal stress (S1) distribution
induced by a remotely applied tension (�n) of 213 MPa.
Fig. 3. Fatigue curve of Ti–6Al–4V smooth specimens.
Fig. 4. S–N curve of Ti–6Al–4V double blunt V-nothced specimens.
over 1 million cycles are considered as run out and marked up with an arrow. It can be
noted that the difference between the Wohler curves are related only to the mean value of
the stress amplitude at 1 106� cycles, but not to the scatter index T� . The fatigue strength of
double circular notched specimens at 1 million cycles was 213 MPa compared to a value of
243 MPa related to the fatigue strength of smooth samples
2.2. Microstructure and Fractography. A preliminary microstructure investigation by
means of OM showed an almost porosity-free material. Some occasional porosity was
found which dimension was less than 50 �m. OM and ESEM micrographs are shown in
Fig. 5. The grains appear acicular with a prevalence of �� plates surrounded by a little
percentage of phase. In Fig. 5a the primary equiassic morphology of phase prior to the
�
� transformation can be also observed. In Fig. 5b the Al-reach black zones correspond
to �� phase, tempered by stress-relief heat treatment, while the white zones, reach in
vanadium, correspond to phase. Such a microstructure is due to the high cooling rate that
characterizes the SLM process and the subsequent heat treatment below 800�C.
ESEM fractographs of the smooth and blunt circular notched specimens are shown in
Figs. 6 and 7, respectively. It is noted that fatigue cracks nucleate at the specimen surface
both in smooth and double U-notched specimens where severe intrusions (Fig. 6d), due to
the roughness induced by the process, act as crack initiation points (Figs. 6d and 7). The
fracture nucleates at one point at the surface of the smooth specimen (Fig. 6d) and
propagates towards the opposite edge covering almost the entire cross section of the
specimen until the final rupture. The final fracture surface, characterized by dimples
(Fig. 6c), was found to be inclined by about 45� with respect to the load direction (Fig 6a).
No porosity was observed on fracture surface of all specimens. In a similar way, fatigue
cracks nucleate at both the notch tip of the double circular notched specimen. Thus, the
final fracture surface appears in between the two propagation zones and still inclined by
about 45� with respect to the load direction. Figure 7 shows a typical deep intrusion where a
crack nucleated.
Finally, despite the several detected high intrusions at the surface that act as easy
crack nucleation zones, it was found that fatigue cycles spent for crack nucleation were
much higher than those spent for crack propagation (Fig. 8).
In Fig. 8 the stiffness of both a smooth and a circular notched specimen loaded with
the same remotely applied stress (� n � 360 MPa) was plotted against the cycles number. It
is noted that the stiffness of both specimens remains constant for about 90% of the fatigue
life. In particular, the crack nucleation period was set equal to the number of cycles beyond
which all the experimental points fall down under the interpolation straight line shown in
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3 109
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens ...
Fig. 5. Optical microscope (a) and environmental scanning electron microscope (b) micrographs of
the analyses material.
Fig. 8. By analyzing all specimens with this procedure, it was found that the percentages of
fatigue life spent for crack nucleation were 93 and 81% for smooth and circular notched
specimen, respectively.
3. Discussion. By using the obtained experimental data, the notch sensitivity has been
calculated. The notch sensitivity (q) is defined by Eq. (1):
q
K
K
f
t
�
�
�
1
1
, (1)
110 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3
S. M. J. Razavi, P. Ferro, and F. Berto
Fig. 6. ESEM fractographs of the smooth specimen (�� � 360 MPa, N � 106,374 cycles).
Fig. 7. ESEM fractographs of the double circular notched specimen (�� � 360 MPa, N � 64,427
cycles).
where K f is the fatigue notch factor (K f A
smooth
A
V nothc� �� �� � ) and K t is the stress
concentration factor defined by maximum local stress to nominal stress ratio (K t �
� � �max )nom [20]. The nominal stress is defined as the mean stress across the reduced
cross-section of the specimen in the presence of the notch. In general, 0 1
q . When the
theoretical stress concentration factor equals the fatigue notch factor (i.e., K Kf t� ), q� 1. If
the notch has no adverse effect on the fatigue limit (i.e., K f � 1), q� 0. By using the fatigue
data obtained in this work, K f � 1.141. K t was found equal to 3.925 by a numerical
simulation. This results in a q value equal to 0.048.
A low notch sensitivity of the wrought Ti–6Al–4V alloy was already observed by
Hosseini [20]. She justified such alloy behavior through alpha hexagonal close packed
(hcp) crystal lattice characteristics. Compared to cubic lattices, such as face central cubic
(fcc) or body central cubic (bcc) lattice, the slip planes in hcp lattice are all parallel to each
other (planes (0001) in Miller–Bravais system). The slip systems number for dislocations in
a hcp lattice are thus very low if compared to those in a cubic crystal (CC). Now,
dislocations play a key role in the fatigue crack nucleation phase. It has been revealed that
after a large number of fatigue loading cycles, dislocations pile up and form structures
called persistent slip bands (PSB). Such PSB can be formed more easily in a crystal grain
that has an unfavourable orientation of its slip planes relative to the planes of maximum
applied shear stresses (Fig. 9). Because of its few slip systems, for a hcp lattice, such
unfavourable orientations are very few. In this situation, many potential damage initiation
sites occur within the volume of a smooth specimen but, at the sharp notch, it is possible
that almost no damage initiation site occurs in the small region around the notch tip where
the stress is near its peak value. Hence, considering the local notch stress, the notched
member can be more resistant to fatigue.
As shown in Figs. 6 and 7, fatigue cracks were observed to initiate on severe surface
intrusions due to the high roughness induced by the process itself. Such intrusions are
covered by an oxide layer which was formed during the stress-relief heat treatment and
non-cleaned up by the grinding treatment. Now, the number of potential crack initiation
intrusions is thought to be much higher in smooth specimens than in the sharp V-notch
specimen where there is the possibility that no such critical surface defects occur in the
small region near the notch tip. It is thought that this effect and the alpha prime hcp lattice
characteristics may justify the very low notch sensitivity of the SLM-processed Ti–6Al–4V
alloy observed by experiments.
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3 111
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens ...
Fig. 8. Specimen stiffness as a function of cycles number of a smooth and a circular notched
specimen, both loaded with a nominal stress (�n) value of 360 MPa.
In order to better comprehend the mechanism of crack nucleation in alpha phase, the
fatigue test of a specimen with double circular notch was interrupted when its stiffness
values started to fall down. The resulting fatigue cracks were then observed by means of
electron backscattered diffraction (EBSD) technique. Figure 10 shows SEM and EBSD
micrographs of a fatigue crack and corresponding alpha grains orientation at the initiation
and propagation zones. It is observed how the basal slip planes of the alpha grain at the
crack initiation zone are oriented about 45� compared to the load direction.
112 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3
S. M. J. Razavi, P. Ferro, and F. Berto
Fig. 9. Schematic representation of PSB formed in a crystal grain that has an unfavourable orientation
of its (0001) slip planes relative to the planes of maximum applied shear stresses.
Fig. 10. SEM and EBSD micrograph of a fatigue crack in a circular notched specimen.
Conclusions. The fatigue strength of Ti–6Al–4V circular notched specimens produced
by SLM was assessed. Results were compared with those corresponding to smooth
specimens and scanning electron microscopy have been used to investigate the fracture
surface of broken specimens in order to identify crack initiation points and fracture
mechanisms. Despite the fatigue specimens were weakened by the sharp circular notch, a
very low notch sensitivity was measured. This was attributed both to the hexagonal crystal
lattice of tempered alpha prime grains and to the high roughness detected on specimen
surface.
Ð å ç þ ì å
Ñïåöèàëüíûå òåõíîëîãèè ïðîèçâîäñòâà ïîçâîëÿþò ýêîíîìè÷åñêè îáîñíîâàíî èçãî-
òîâëÿòü äåòàëè ñëîæíîé êîíôèãóðàöèè ñ ìèíèìèçàöèåé öèêëà îò ðàçðàáîòêè äî ïðî-
èçâîäñòâà. Äëÿ ïðèìåíåíèÿ ýòîé òåõíîëîãèè ê âûñîêîíàãðóæåííûì îòâåòñòâåííûì
ýëåìåíòàì êîíñòðóêöèé íåîáõîäèìî èçó÷èòü ñïåöèôèêó åå âëèÿíèÿ íà õàðàêòåðèñ-
òèêè óñòàëîñòè ïîëó÷åííûõ ìàòåðèàëîâ íà ìèêðî-, ìàêðî- è ìåçîóðîâíå. Èññëåäóåòñÿ
óñòàëîñòíàÿ ïðî÷íîñòü ïëîñêèõ îáðàçöîâ (ãëàäêèå è ñ äâóõñòîðîííèìè ïîëóêðóã-
ëûìè âûðåçàìè) èç ñïëàâà Ti–6Al–4V, èçãîòîâëåííûõ ïî òåõíîëîãèè èçáèðàòåëüíîé
ëàçåðíîé ïëàâêè. Äëÿ èäåíòèôèêàöèè ìåñò çàðîæäåíèÿ óñòàëîñòíîé òðåùèíû è ìåõà-
íèçìà ðàçðóøåíèÿ ôðàêòîãðàììû ðàçðóøåííûõ îáðàçöîâ èññëåäîâàëèñü ìåòîäîì
ñêàíèðóþùåé ýëåêòðîííîé ìèêðîñêîïèè. Óñòàíîâëåíî, ÷òî óñòàëîñòíàÿ ïðî÷íîñòü
îáðàçöîâ ñ êîíöåíòðàòîðîì íàïðÿæåíèé â âèäå äâóõñòîðîííèõ ïîëóêðóãëûõ âûðåçîâ
íåçíà÷èòåëüíî íèæå, ÷åì ãëàäêèõ îáðàçöîâ. Ïîêàçàíî, ÷òî ÷óâñòâèòåëüíîñòü äàííîãî
ìàòåðèàëà ê êîíöåíòðàöèè íàïðÿæåíèé î÷åíü íèçêàÿ èç-çà ñïåöèôèêè ãåêñàãîíàëüíîé
êðèñòàëëè÷åñêîé ðåøåòêè çàêàëåííûõ ïåðâè÷íûõ àëüôà-çåðåí è òåõíîëîãè÷åñêèõ
ïîâåðõíîñòíûõ äåôåêòîâ, õàðàêòåðíûõ äëÿ èçáèðàòåëüíîé ëàçåðíîé ïëàâêè.
1. M. Todai, T. Nakano, T. Liu, et al., “Effect of building direction on the microstructure
and tensile properties of Ti-48Al-2Cr-2Nb alloy additively manufactured by electron
beam melting,” Addit. Manuf., 13, 61–70 (2017).
2. A. Domashenkov, A. Plotnikova, I. Movchan, et al., “Microstructure and physical
properties of a Ni/Fe-based superalloy processed by Selective Laser Melting,” Addit.
Manuf., 15, 66–77 (2017).
3. Y. S. Lee and W. Zhang, “Modeling of heat transfer, fluid flow and solidification
microstructure of nickel-base superalloy fabricated by laser powder bed fusion,”
Addit. Manuf., 12, Part B, 178–188 (2016).
4. L. E. Lindgren, A. Lundbäck, M. Fisk, et al., “Simulation of additive manufacturing
using coupled constitutive and microstructure models,” Addit. Manuf., 12, Part B,
144–158 (2016).
5. X. Wu, J. Liang, J. Mei, et al., “Microstructures of laser-deposited Ti–6Al–4V,”
Mater. Design, 25, No. 2, 137–144 (2014).
6. E. Wycisk, S. Siddique, D. Herzog, et al., “Fatigue performance of laser additive
manufactured Ti–6A–4V in very high cycle fatigue regime up to 109 cycles,” Front.
Mater., 2 (2015), DOI: 10.3389/fmats.2015.00072.
7. T. Vilaro, C. Colin, and J. D. Bartout, “As-fabricated and heat-treated microstructures
of the Ti-6Al-4V alloy processed by selective laser melting,” Metall. Mater. Trans. A,
42, No. 10, 3190–3199 (2011).
8. J. P. Kruth, P. Mercelis, J. Van Vaerenbergh, et al., “Binding mechanism in selective
laser sintering and selective laser melting,” Rapid Prototyp. J., 11, No. 1, 26–36
(2005).
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3 113
Fatigue Assessment of Ti–6Al–4V Circular Notched Specimens ...
9. B. Vrancken, L. Thijs, J. P. Kruth, and J. V. Humbeeck, “Heat treatment of T6Al4V
produced by selective laser melting: microstructure and mechanical properties,” J.
Alloy. Compd., 541, 177–185 (2012).
10. N. E. Cherolis, “Fatigue in the aerospace industry: Striations,” J. Fail. Anal. Preven.,
8, No. 3, 255–258 (2008).
11. X. Song, L. Wang, M. Niinomi, et al., “Microstructure and fatigue behaviors of a
biomedical Ti–Nb–Ta–Zr alloy with trace CeO2 additions,” Mater. Sci. Eng. A, 619,
112–118 (2014).
12. Z. Sun, M. Chemkhi, P. Kanoute, and D. Retraint, “Fatigue properties of a biomedical
316L steel processed by surface mechanical attrition,” IOP Conf. Ser.: Mater. Sci.
Eng., 63, 012021 (2014), DOI: 10.1088/1757-899X/63/1/012021.
13. S. Leuders, M. Thöne, A. Riemer, et al., “On the mechanical behaviour of titanium
alloy TiAl6V4 manufactured by selective laser melting: fatigue resistance and crack
growth performance,” Int. J. Fatigue, 48, 300–307 (2013).
14. G. Kasperovich and J. Hausmann, “Improvement of fatigue resistance and ductility of
TiAl6V4 processed by selective laser melting,” J. Mater. Process. Tech., 220, 202–
214 (2015).
15. F. Berto and E. Barati, “Fracture assessment of U-notches under three point bending
by means of local energy density,” Mater. Design, 32, No. 2, 822–830 (2011).
16. F. Berto, P. Lazzarin, and M. R. Ayatollahi, “Brittle fracture of sharp and blunt
V-notches in isostatic graphite under pure compression loading,” Carbon, 63, 101–
116 (2013).
17. F. Berto, P. Lazzarin, and C. Marangon, “Fatigue strength of notched specimens made
of 40CrMoV13. 9 under multiaxial loading,” Mater. Design, 54, 57–66 (2014).
18. S. M. J. Razavi, M. R. Ayatollahi, C. Sommitsch, and C. Moser, “Retardation of
fatigue crack growth in high strength steel S690 using a modified stop-hole technique,”
Eng. Fract. Mech., 169, 226–237 (2017).
19. M. R. Ayatollahi, S. M. J. Razavi, C. Sommitsch, and C. Moser, “Fatigue life
extension by crack repair using double stop-hole technique,” Mater. Sci. Forum, 879,
3–8 (2017).
20. S. Hosseini, “Fatigue of Ti-6Al-4V,” in: R. Hudak, M. Penhaker, and J. Majernik
(Eds.), Biomedical Engineering – Technical Applications in Medicine, Ch. 3, InTech,
Rijeka (2012), pp. 75–92, ISBN 978-953-51-0733-0.
Received 12. 12. 2016
114 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2017, ¹ 3
S. M. J. Razavi, P. Ferro, and F. Berto
<<
/ASCII85EncodePages false
/AllowTransparency false
/AutoPositionEPSFiles true
/AutoRotatePages /None
/Binding /Left
/CalGrayProfile (Dot Gain 20%)
/CalRGBProfile (sRGB IEC61966-2.1)
/CalCMYKProfile (U.S. Web Coated \050SWOP\051 v2)
/sRGBProfile (sRGB IEC61966-2.1)
/CannotEmbedFontPolicy /Error
/CompatibilityLevel 1.4
/CompressObjects /Tags
/CompressPages true
/ConvertImagesToIndexed true
/PassThroughJPEGImages true
/CreateJobTicket false
/DefaultRenderingIntent /Default
/DetectBlends true
/DetectCurves 0.0000
/ColorConversionStrategy /CMYK
/DoThumbnails false
/EmbedAllFonts true
/EmbedOpenType false
/ParseICCProfilesInComments true
/EmbedJobOptions true
/DSCReportingLevel 0
/EmitDSCWarnings false
/EndPage -1
/ImageMemory 1048576
/LockDistillerParams false
/MaxSubsetPct 100
/Optimize true
/OPM 1
/ParseDSCComments true
/ParseDSCCommentsForDocInfo true
/PreserveCopyPage true
/PreserveDICMYKValues true
/PreserveEPSInfo true
/PreserveFlatness true
/PreserveHalftoneInfo false
/PreserveOPIComments false
/PreserveOverprintSettings true
/StartPage 1
/SubsetFonts true
/TransferFunctionInfo /Apply
/UCRandBGInfo /Preserve
/UsePrologue false
/ColorSettingsFile ()
/AlwaysEmbed [ true
]
/NeverEmbed [ true
]
/AntiAliasColorImages false
/CropColorImages true
/ColorImageMinResolution 300
/ColorImageMinResolutionPolicy /OK
/DownsampleColorImages true
/ColorImageDownsampleType /Bicubic
/ColorImageResolution 1200
/ColorImageDepth -1
/ColorImageMinDownsampleDepth 1
/ColorImageDownsampleThreshold 1.50000
/EncodeColorImages false
/ColorImageFilter /DCTEncode
/AutoFilterColorImages true
/ColorImageAutoFilterStrategy /JPEG
/ColorACSImageDict <<
/QFactor 0.15
/HSamples [1 1 1 1] /VSamples [1 1 1 1]
>>
/ColorImageDict <<
/QFactor 0.15
/HSamples [1 1 1 1] /VSamples [1 1 1 1]
>>
/JPEG2000ColorACSImageDict <<
/TileWidth 256
/TileHeight 256
/Quality 30
>>
/JPEG2000ColorImageDict <<
/TileWidth 256
/TileHeight 256
/Quality 30
>>
/AntiAliasGrayImages false
/CropGrayImages true
/GrayImageMinResolution 300
/GrayImageMinResolutionPolicy /OK
/DownsampleGrayImages true
/GrayImageDownsampleType /Bicubic
/GrayImageResolution 1200
/GrayImageDepth -1
/GrayImageMinDownsampleDepth 2
/GrayImageDownsampleThreshold 1.50000
/EncodeGrayImages false
/GrayImageFilter /DCTEncode
/AutoFilterGrayImages true
/GrayImageAutoFilterStrategy /JPEG
/GrayACSImageDict <<
/QFactor 0.15
/HSamples [1 1 1 1] /VSamples [1 1 1 1]
>>
/GrayImageDict <<
/QFactor 0.15
/HSamples [1 1 1 1] /VSamples [1 1 1 1]
>>
/JPEG2000GrayACSImageDict <<
/TileWidth 256
/TileHeight 256
/Quality 30
>>
/JPEG2000GrayImageDict <<
/TileWidth 256
/TileHeight 256
/Quality 30
>>
/AntiAliasMonoImages false
/CropMonoImages true
/MonoImageMinResolution 1200
/MonoImageMinResolutionPolicy /OK
/DownsampleMonoImages true
/MonoImageDownsampleType /Bicubic
/MonoImageResolution 1200
/MonoImageDepth -1
/MonoImageDownsampleThreshold 1.50000
/EncodeMonoImages false
/MonoImageFilter /CCITTFaxEncode
/MonoImageDict <<
/K -1
>>
/AllowPSXObjects false
/CheckCompliance [
/None
]
/PDFX1aCheck false
/PDFX3Check false
/PDFXCompliantPDFOnly false
/PDFXNoTrimBoxError true
/PDFXTrimBoxToMediaBoxOffset [
0.00000
0.00000
0.00000
0.00000
]
/PDFXSetBleedBoxToMediaBox true
/PDFXBleedBoxToTrimBoxOffset [
0.00000
0.00000
0.00000
0.00000
]
/PDFXOutputIntentProfile (None)
/PDFXOutputConditionIdentifier ()
/PDFXOutputCondition ()
/PDFXRegistryName ()
/PDFXTrapped /False
/CreateJDFFile false
/Description <<
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
/BGR <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>
/CHS <FEFF4f7f75288fd94e9b8bbe5b9a521b5efa7684002000410064006f006200650020005000440046002065876863900275284e8e9ad88d2891cf76845370524d53705237300260a853ef4ee54f7f75280020004100630072006f0062006100740020548c002000410064006f00620065002000520065006100640065007200200035002e003000204ee553ca66f49ad87248672c676562535f00521b5efa768400200050004400460020658768633002>
/CHT <FEFF4f7f752890194e9b8a2d7f6e5efa7acb7684002000410064006f006200650020005000440046002065874ef69069752865bc9ad854c18cea76845370524d5370523786557406300260a853ef4ee54f7f75280020004100630072006f0062006100740020548c002000410064006f00620065002000520065006100640065007200200035002e003000204ee553ca66f49ad87248672c4f86958b555f5df25efa7acb76840020005000440046002065874ef63002>
/CZE <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>
/DAN <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>
/DEU <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>
/ESP <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>
/ETI <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>
/FRA <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>
/GRE <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>
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
/HRV (Za stvaranje Adobe PDF dokumenata najpogodnijih za visokokvalitetni ispis prije tiskanja koristite ove postavke. Stvoreni PDF dokumenti mogu se otvoriti Acrobat i Adobe Reader 5.0 i kasnijim verzijama.)
/HUN <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>
/ITA <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>
/JPN <FEFF9ad854c18cea306a30d730ea30d730ec30b951fa529b7528002000410064006f0062006500200050004400460020658766f8306e4f5c6210306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103055308c305f0020005000440046002030d530a130a430eb306f3001004100630072006f0062006100740020304a30883073002000410064006f00620065002000520065006100640065007200200035002e003000204ee5964d3067958b304f30533068304c3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002>
/KOR <FEFFc7740020c124c815c7440020c0acc6a9d558c5ec0020ace0d488c9c80020c2dcd5d80020c778c1c4c5d00020ac00c7a50020c801d569d55c002000410064006f0062006500200050004400460020bb38c11cb97c0020c791c131d569b2c8b2e4002e0020c774b807ac8c0020c791c131b41c00200050004400460020bb38c11cb2940020004100630072006f0062006100740020bc0f002000410064006f00620065002000520065006100640065007200200035002e00300020c774c0c1c5d0c11c0020c5f40020c2180020c788c2b5b2c8b2e4002e>
/LTH <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>
/LVI <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>
/NLD (Gebruik deze instellingen om Adobe PDF-documenten te maken die zijn geoptimaliseerd voor prepress-afdrukken van hoge kwaliteit. De gemaakte PDF-documenten kunnen worden geopend met Acrobat en Adobe Reader 5.0 en hoger.)
/NOR <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>
/POL <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>
/PTB <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>
/RUM <FEFF005500740069006c0069007a00610163006900200061006300650073007400650020007300650074010300720069002000700065006e007400720075002000610020006300720065006100200064006f00630075006d0065006e00740065002000410064006f006200650020005000440046002000610064006500630076006100740065002000700065006e0074007200750020007400690070010300720069007200650061002000700072006500700072006500730073002000640065002000630061006c006900740061007400650020007300750070006500720069006f006100720103002e002000200044006f00630075006d0065006e00740065006c00650020005000440046002000630072006500610074006500200070006f00740020006600690020006400650073006300680069007300650020006300750020004100630072006f006200610074002c002000410064006f00620065002000520065006100640065007200200035002e00300020015f00690020007600650072007300690075006e0069006c006500200075006c0074006500720069006f006100720065002e>
/SKY <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>
/SLV <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>
/SUO <FEFF004b00e40079007400e40020006e00e40069007400e4002000610073006500740075006b007300690061002c0020006b0075006e0020006c0075006f00740020006c00e400680069006e006e00e4002000760061006100740069007600610061006e0020007000610069006e006100740075006b00730065006e002000760061006c006d0069007300740065006c00750074007900f6006800f6006e00200073006f00700069007600690061002000410064006f0062006500200050004400460020002d0064006f006b0075006d0065006e007400740065006a0061002e0020004c0075006f0064007500740020005000440046002d0064006f006b0075006d0065006e00740069007400200076006f0069006400610061006e0020006100760061007400610020004100630072006f0062006100740069006c006c00610020006a0061002000410064006f00620065002000520065006100640065007200200035002e0030003a006c006c00610020006a006100200075007500640065006d006d0069006c006c0061002e>
/SVE <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>
/TUR <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>
/UKR <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>
/ENU (Use these settings to create Adobe PDF documents best suited for high-quality prepress printing. Created PDF documents can be opened with Acrobat and Adobe Reader 5.0 and later.)
/RUS <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>
>>
/Namespace [
(Adobe)
(Common)
(1.0)
]
/OtherNamespaces [
<<
/AsReaderSpreads false
/CropImagesToFrames true
/ErrorControl /WarnAndContinue
/FlattenerIgnoreSpreadOverrides false
/IncludeGuidesGrids false
/IncludeNonPrinting false
/IncludeSlug false
/Namespace [
(Adobe)
(InDesign)
(4.0)
]
/OmitPlacedBitmaps false
/OmitPlacedEPS false
/OmitPlacedPDF false
/SimulateOverprint /Legacy
>>
<<
/AddBleedMarks false
/AddColorBars false
/AddCropMarks false
/AddPageInfo false
/AddRegMarks false
/ConvertColors /ConvertToCMYK
/DestinationProfileName ()
/DestinationProfileSelector /DocumentCMYK
/Downsample16BitImages true
/FlattenerPreset <<
/PresetSelector /MediumResolution
>>
/FormElements false
/GenerateStructure false
/IncludeBookmarks false
/IncludeHyperlinks false
/IncludeInteractive false
/IncludeLayers false
/IncludeProfiles false
/MultimediaHandling /UseObjectSettings
/Namespace [
(Adobe)
(CreativeSuite)
(2.0)
]
/PDFXOutputIntentProfileSelector /DocumentCMYK
/PreserveEditing true
/UntaggedCMYKHandling /LeaveUntagged
/UntaggedRGBHandling /UseDocumentProfile
/UseDocumentBleed false
>>
]
>> setdistillerparams
<<
/HWResolution [2400 2400]
/PageSize [612.000 792.000]
>> setpagedevice
|