Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water
Rotary bending fatigue tests were conducted in laboratory air and distilled water using three extruded magnesium (Mg) alloys AZ80, AZ61, and AM60 with different chemical compositions. In laboratory air, thefatigue strengths at high stress levels were similar in all alloys because cracks initiated at...
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| Опубліковано в: : | Проблемы прочности |
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| Дата: | 2008 |
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| Мова: | Англійська |
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
2008
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| Цитувати: | Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water / Y. Uematsu, K. Tokaji, T. Ohashi // Проблемы прочности. — 2008. — № 1. — С. 141-145. — Бібліогр.: 3 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859725593796411392 |
|---|---|
| author | Uematsu, Y. Tokaji, K. Ohashi, T. |
| author_facet | Uematsu, Y. Tokaji, K. Ohashi, T. |
| citation_txt | Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water / Y. Uematsu, K. Tokaji, T. Ohashi // Проблемы прочности. — 2008. — № 1. — С. 141-145. — Бібліогр.: 3 назв. — англ. |
| collection | DSpace DC |
| container_title | Проблемы прочности |
| description | Rotary bending fatigue tests were conducted in laboratory air and distilled water using three extruded magnesium (Mg) alloys AZ80, AZ61, and AM60 with different chemical compositions. In laboratory air, thefatigue strengths at high stress levels were similar in all alloys because cracks initiated at Al-Mn intermetallic compounds, whereas AZ80 with the largest Al content exhibited the highestfatigue strength at low stress levels, which was attributed to the crack initiation due to cyclic slip deformation in the matrix microstructure. In distilled water, fatigue strengths were considerably decreased due to theformation of corrosion pits in all alloys, and the difference of fatigue strength at low stress levels among the alloys disappeared, indicating that the addition ofAl that improved the fatigue strength in laboratory air was detrimental to corrosion fatigue.
С использованием методики сварки трения были получены соединения двух алюминиевых сплавов: литого (АС4СН-Т6) и обработанного давлением (А6061-Т6). Исследовалось влияние микроструктуры и послетепературной обработки на сопротивление усталости различных сварных соединений. Центральная часть зоны сварки характеризуется более низкими значения твердости по Виккерсу, чем зоны основных металлов, при чем минимальные значения твердости были зафиксированы на пути перемещения сварочного инструмента. Статическое разрушение сварных соединений при растяжении имело место со стороны основного сплава А6061, где твердость была минимальна, при чем статическая прочность сварного соединения из разнородных сплавов была ниже, чем у сплавов АС4СН и А6061. Усталостное разрушение имело место для основного сплава АС4СН, что связано с наличием в нем литейных дефектов, причем усталостная прочность сварного соединения из разнородных сплавов оказалась такой же, как сплава АС4СН, но ниже, чем сплава А6061. При менение методики сварки трением и после- температурной обработки позволило повысить усталостную прочность сварных соединений разнородных сплавов до уровня основного сплава А6061.
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| first_indexed | 2025-12-01T11:17:05Z |
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| fulltext |
UDC 539. 4
C o r r o s io n F a t ig u e B e h a v io r o f E x tr u d e d A Z 8 0 , A Z 6 1 , a n d A M 6 0 M a g n e s iu m
A llo y s in D is t i l le d W a te r
Y . U em a tsu ,1a K . T o k a ji,1b and T . O h ash i2
1 Gifu University, Gifu, Japan
2 Brother Industries Ltd, Nagoya, Japan
a yuematsu@gifu-u.ac.jp, b tokaji@gifu-u.ac.jp
Rotary bending fatigue tests were conducted in laboratory air and distilled water using three
extruded magnesium (Mg) alloys AZ80, AZ61, and AM60 with different chemical compositions. In
laboratory air, the fatigue strengths at high stress levels were similar in all alloys because cracks
initiated at Al-Mn intermetallic compounds, whereas AZ80 with the largest Al content exhibited the
highest fatigue strength at low stress levels, which was attributed to the crack initiation due to
cyclic slip deformation in the matrix microstructure. In distilled water, fatigue strengths were
considerably decreased due to the formation o f corrosion p its in all alloys, and the difference o f
fatigue strength at low stress levels among the alloys disappeared, indicating that the addition o f Al
that improved the fatigue strength in laboratory air was detrimental to corrosion fatigue.
K eyw ords: fatigue, corrosion fatigue, m agnesium alloy, crack initiation.
In trod u ction . M g alloys have recently received considerable attention due to their
excellent properties such as light w eight, h igh specific strength and stiffness, etc. W rought
M g alloys have superior m echanical properties to cast M g alloys, but various fatigue
properties should be evaluated in detail for their applications to load-bearing com ponents
[1]. Furthermore, it is w ell know n that M g alloys have poor corrosion resistance [2].
Therefore, understanding the corrosion fatigue behavior o f M g alloys is also very
important [3]. In the present study, rotary bending fatigue tests have been perform ed in
laboratory air and distilled water using three extruded M g alloys A Z 80, A Z 61, and A M 60
w ith different chem ical com positions, w here the A l and Zn contents are considerably
different. The effect o f chem ical com position o f M g alloys on corrosion fatigue behavior
w as discussed.
E xp er im en ta l D etails. M a teria ls a n d S pecim en . The materials used are extruded
A Z 80, A Z 61, and A M 60 alloys. Their chem ical com positions (wt.%) and m echanical
properties are listed in Tables 1 and 2, respectively. The tensile strength increases w ith
increasing the A l content. The average grain sizes are 12, 17.9, and 8.7 fxm for A Z80,
A Z 61, and A M 60, respectively. Sm ooth fatigue specim ens w ith a diameter o f 8 m m and a
gauge length o f 10 m m were m achined from the extruded materials. A ll specim ens were
sam pled from the sam e lo t extruded bars in order to avoid large scatter in S — N data.
P ro ced u res . Fatigue tests w ere performed using a 98 N m capacity rotary bending
fatigue testing m achine operating at a frequency o f 20 H z in laboratory air. Corrosion
fatigue tests were conducted using the sam e testing m achine w here distilled water w as
dropped onto the centre o f gauge length by a m etering pump w h ose flow rate w as 140
m l/m in.
R esu lts and D iscu ssion . F atigu e B eh a v io r in L a b o ra to ry A ir. F atigue Strength. In
the fo llow ing Figures 1, 5 and 6, the test results in laboratory air and distilled water are
show n by open and solid sym bols, respectively. The S — N diagram is revealed in Fig. 1.
The fatigue strengths at h igh stress levels are similar in all alloys, indicating that chem ical
com position has little effect. H ow ever, the fatigue lim its defined as the fatigue strengths at
N = 107 cycles are 80 M Pa for A Z61 and A M 60 and 100 M Pa for A Z80. Therefore, the
addition o f A l can im prove not on ly tensile strength but also fatigue limit.
© Y. U EM A TSU , K. TO K A JI, T. O H A SH I, 2008
ISSN 0556-171X. Проблемы прочности, 2008, № 1 141
mailto:yuematsu@gifu-u.ac.jp
mailto:tokaji@gifu-u.ac.jp
Y. Uematsu, K. Tokaji, and T. Ohashi
T a b l e 1
Chemical Compositions of Materials (wt.%)
Material Al Zn Mn Ni Cu Fe Si Pb Ca Sn Mg
AZ80 8.З 0.60 0.23 0.0010 0.0020 0.002 0.0З0 — — — Bal.
AZ61 б.4 0.74 0.35 0.0012 0.0029 0.001 0.015 0.001 0.001 <0.001 Bal.
AM60 6.0 0.02 0.32 0.0005 0.00З0 0.00З 0.0З0 — — — Bal.
T a b l e 2
Mechanical Properties of Materials
Material 0.2% proof stress
°0.2 , MPa
Tensile strength
Ob, MPa
Elongation
&,%
Reduction o f area
V , %
AZ80 196 273 14.б 1З.1
AZ61 186 248 14.0 2З.8
AM60 196 24б 1З.1 З2.б
Fig. 1. S — N diagram.
• V' й
Fig. 2. EDX analysis results at crack initiation
site in AM60 (a = 140 MPa): (a) SEM image,
(b) Mg, (c) Al, (d) Mn.
C rack Initiation Behavior. Figure 2a indicates SEM micrograph o f crack initiation
site in A M 60, where the stress level, a , w as 140 MPa. The crack is initiated due to the
breakage o f an inclusion. The results o f E D X m apping analysis are also show n in the
figure, w hich indicates that the inclusion m ainly consists o f aluminum and m anganese,
thus it w as identified as A l-M n -based intermetallic com pound. Sim ilar inclusions were
also recognized in A Z 80 and A Z61. The SEM micrographs o f fracture surface near crack
initiation site are revealed in Figs. 3 and 4 for h igh and low stress levels, respectively.
Inclusions are recognized at the crack initiation site in all alloys as shown by arrow in Fig. 3
at h igh stress level ( a = 150 M Pa), w hile not in Fig. 4 at low stress level ( a = 110 MPa).
Inclusions were observed at the crack initiation sites in all alloys on ly w hen stress levels
w ere higher than 130 MPa. Therefore, it is concluded that cracks are initiated from
inclusion at h igh stress levels, w h ile due to cyclic slip deform ation in the matrix
microstructure w hen stress levels were low er than 130 M Pa as show n in Fig. 4.
Sm all C rack G rowth Behavior. The surface crack length, 2c, is represented in Fig. 5
as a function o f cycle ratio, N /N f (N f is fatigue life). Cracks initiated at an early stage
o f fatigue life, indicating that fatigue life w as dom inated m ainly by sm all crack growth.
Figure 6 show s the relationship betw een crack growth rate, d a /d N , and m axim um stress
intensity factor, K max. The crack growth rates becom e slightly slow er in the order o f
142 ISSN Ü556-171X. Проблемы прочности, 2ÜÜ8, № l
Corrosion Fatigue Behavior o f Extruded
A M 60, A Z 61, and A Z 80, revealing that the addition o f A l can im prove sm all crack
growth resistance.
It is believed that crack initiation from inclusion at h igh stress levels results in the
similar fatigue strength regardless o f chem ical com position, w hile w hen lo w stresses were
applied, cracks initiated due to cyclic slip deform ation. Therefore, A Z 80 w ith the highest
A l content and tensile strength has the highest fatigue limit.
Fig. 3. SEM micrographs showing crack initiation site in laboratory air (a = 150 MPa): (a) AZ80,
(b) AZ61, (c) AM60.
Fig. 4. SEM micrographs showing crack initiation site in laboratory air (a :
(b) AZ61, (c) AM60.
: 110 MPa): (a) AZ80,
Fig. 5 Fig. 6
Fig. 5. Relationship between surface crack length and cycle ratio.
Fig. 6. Relationship between crack growth rate and maximum stress intensity factor.
F atigu e B eh a v io r in D is tille d Water. F atigue Strength. The fatigue strengths at high
stress levels in distilled water are similar to those in laboratory air, w hile fatigue fracture
occurs even i f stress levels are low er than the fatigue lim it in laboratory air. The fatigue
strengths o f all alloys are nearly the sam e, thus A Z 80 that exhibited the highest fatigue
lim it in laboratory air is m ost sensitive to the corrosive environment.
C rack Initiation Behavior. Figure 7 show s SEM micrographs o f fracture surface near
crack initiation site at a stress level o f 50 M Pa that is low er than the fatigue lim it in
laboratory air. The specim en w as tilted about an angle o f 45° in order to observe the
ISSN 0556-171X. npoôëeMbi npounocmu, 2008, N 1 143
Y. Uematsu, K. Tokaji, and T. Ohashi
specim en surface. It is clear that the specim en surface is covered by cracked corrosion
product, and corrosion pit show n by allow is recognized at the crack initiation site. Figure 8
represents the specim en surfaces o f A M 60 tested at a stress level o f 50 M Pa in distilled
water. In all alloys, the specim en surfaces are covered by corrosion product and m any
corrosion pits are form ed as typically seen in Fig. 8. H ow ever, corrosion pits w ere not
recognized on the specim en surface or the crack initiation site w hen higher stresses were
applied, nam ely test period w as short. Therefore, it can be concluded that corrosion pit is
form ed at low stress levels, w here test period w as long, and cracks initiate from the
corrosion pit, leading to the fatigue failure b elow the fatigue lim it in laboratory air.
Fig. 7. SEM micrographs showing crack initiation site in distilled water (a = 50 MPa): (a) AZ80,
(b) AZ61, (c) AM60.
Fig. 8. Specimen surfaces o f AM60 (a = 50 MPa).
Sm all C rack G rowth Behavior. The relationship betw een 2c and N / N f in Fig. 5
reveals that cracks initiated at the stage w here N / N f w as larger than 0.4 in distilled
water, w hile at an early stage in laboratory air. It im plies that corrosion pits are form ed in
an early stage o f fatigue life in distilled water. Crack growth rates are show n in Fig. 6 as a
function o f K max. The crack growth rates in distilled water are nearly the sam e as those
in laboratory air, and the dependence o f crack growth rate on chem ical com position
observed in laboratory air disappears in distilled water.
Fig. 9. Anode polarization curves in distilled water.
144 ISSN 0556-171X. npoôëeMbi npounocmu, 2008, N 1
Corrosion Fatigue Behavior o f Extruded
E ffect o f C hem ical C om position. Figure 9 indicates the anode polarization curves in
distilled water. The corrosion potentials are alm ost the sam e in all a lloys, w hile the
corrosion rate is fastest in A Z80. It is b elieved that the h ighest sensitivity o f A Z 80 to
corrosive environm ent is attributed to the electrochem ical nature o f A Z 80. Therefore, it
can be concluded that the addition o f A l can contribute to im proving the fatigue lim it in
laboratory air, w hile enhances the sensitivity against corrosive environment. Fatigue
behavior in laboratory air and d istilled water w as similar betw een A Z61 and A M 60, thus
the addition o f Zn has no effect on fatigue strength and corrosion resistance.
C on clu sions. Rotary bending fatigue tests w ere conducted in laboratory air and
distilled water using three extruded M g alloys A Z 80, A Z 61, and A M 60 w ith different
chem ical com positions. In laboratory air, A Z 80 w ith the largest A l content had the highest
fatigue limit, because crack initiation w as due to cyclic slip deform ation at low stress
levels. H ow ever, corrosion fatigue strengths w ere alm ost the sam e in all alloys, indicating
that the sensitivity against corrosive environm ent w as enhanced by the addition o f Al.
1. Y. Uematsu, K. Tokaji, M. Kamakura, et al., Mater. Sci. Eng., A434, 131 (2006).
2. R. S. Stameppa, R. P. M. Procter, and V. Ashworth, Corrosion Science, 24, 325 (1984).
3. Y. Unigovski, A. Eliezer, E. Abramov, et al., Mater. Sci. Eng., A360, 132 (2003).
Received 28. 06. 2007
ISSN 0556-171X. npoôneMbi npoHHocmu, 2008, № 1 145
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| id | nasplib_isofts_kiev_ua-123456789-48425 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0556-171X |
| language | English |
| last_indexed | 2025-12-01T11:17:05Z |
| publishDate | 2008 |
| publisher | Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| record_format | dspace |
| spelling | Uematsu, Y. Tokaji, K. Ohashi, T. 2013-08-19T14:03:02Z 2013-08-19T14:03:02Z 2008 Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water / Y. Uematsu, K. Tokaji, T. Ohashi // Проблемы прочности. — 2008. — № 1. — С. 141-145. — Бібліогр.: 3 назв. — англ. 0556-171X https://nasplib.isofts.kiev.ua/handle/123456789/48425 539.4 Rotary bending fatigue tests were conducted in laboratory air and distilled water using three extruded magnesium (Mg) alloys AZ80, AZ61, and AM60 with different chemical compositions. In laboratory air, thefatigue strengths at high stress levels were similar in all alloys because cracks initiated at Al-Mn intermetallic compounds, whereas AZ80 with the largest Al content exhibited the highestfatigue strength at low stress levels, which was attributed to the crack initiation due to cyclic slip deformation in the matrix microstructure. In distilled water, fatigue strengths were considerably decreased due to theformation of corrosion pits in all alloys, and the difference of fatigue strength at low stress levels among the alloys disappeared, indicating that the addition ofAl that improved the fatigue strength in laboratory air was detrimental to corrosion fatigue. С использованием методики сварки трения были получены соединения двух алюминиевых сплавов: литого (АС4СН-Т6) и обработанного давлением (А6061-Т6). Исследовалось влияние микроструктуры и послетепературной обработки на сопротивление усталости различных сварных соединений. Центральная часть зоны сварки характеризуется более низкими значения твердости по Виккерсу, чем зоны основных металлов, при чем минимальные значения твердости были зафиксированы на пути перемещения сварочного инструмента. Статическое разрушение сварных соединений при растяжении имело место со стороны основного сплава А6061, где твердость была минимальна, при чем статическая прочность сварного соединения из разнородных сплавов была ниже, чем у сплавов АС4СН и А6061. Усталостное разрушение имело место для основного сплава АС4СН, что связано с наличием в нем литейных дефектов, причем усталостная прочность сварного соединения из разнородных сплавов оказалась такой же, как сплава АС4СН, но ниже, чем сплава А6061. При менение методики сварки трением и после- температурной обработки позволило повысить усталостную прочность сварных соединений разнородных сплавов до уровня основного сплава А6061. en Інститут проблем міцності ім. Г.С. Писаренко НАН України Проблемы прочности Научно-технический раздел Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water Коррозионная усталость экструзионных магниевых сплавов AZ80, AZ61 и AM60 в дистиллированной воде Article published earlier |
| spellingShingle | Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water Uematsu, Y. Tokaji, K. Ohashi, T. Научно-технический раздел |
| title | Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water |
| title_alt | Коррозионная усталость экструзионных магниевых сплавов AZ80, AZ61 и AM60 в дистиллированной воде |
| title_full | Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water |
| title_fullStr | Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water |
| title_full_unstemmed | Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water |
| title_short | Corrosion fatigue behavior of extruded AZ80, AZ61, and AM60 magnesium alloys in distilled water |
| title_sort | corrosion fatigue behavior of extruded az80, az61, and am60 magnesium alloys in distilled water |
| topic | Научно-технический раздел |
| topic_facet | Научно-технический раздел |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/48425 |
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