ENCYCLOPÉDIE DE LA RECHERCHE SUR L’ALUMINIUM AU QUÉBEC 2013 | Page 38
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NOUVEAUX PRODUITS ET MATÉRIAUX À BASE D'ALUMINIUM
NEW ALUMINIUM BASED PRODUCTS AND MATERIALS
Effect of Pretreatment on Static Recrystallization
EFFET DU PRÉTRAITEMENT THERMIQUE SUR LE COMPORTEMENT
Behavior of AA 7150 Alloy
À LA RECRISTALLISATION STATIQUE DE L’ALLIAGE AA7150
Effet du prétraitement thermique sur le comportement à la
EFFECT OF PRETREATMENT ON STATIC
recristallisation statique de l’alliage AA 7150
RECRYSTALLIZATION BEHAVIOR OF AA 7150 ALLOY
Zhanying Guo, X.-Grant Chen
NSERC/Rio Tinto Alcan Industrial Research Chair
in Metallurgy of Aluminum Transformation, UQAC
As recrystallization inhibitor, small quantities of Zr are added into
7xxx series Al alloys, which forms fine Al3Zr dispersoids during
homogenization. However, the Zr segregates toward the center of the
grains. In current study, a pretreatment process before
homogenization was designed to improve Al3Zr distribution for the
enhancement of the recrystallization inhibiting effect of Zr in AA 7150
Al alloy.
Alloy Base Alloy
Zn
6.15
1
6.10
Investigating the effect of pretreatment on the static recrystallization
behavior of AA 7150 aluminum alloy containing trace of Zr .
2
5.99
2.10
2.11
0
2.00
2.15
0.04
1.91
2.10
0.09
Fe
Si
Ti
0.13
0.11
0.01
0.13
0.11
0.01
0.13
0.11
0.01
Al
Bal.
Bal.
Bal.
Pretreatment
300 ºC x 48 h, 72 h
400 ºC x 48 h, 72 h
470 ºC x 24 h
(a)
(c)
(e)
=200 µm; Map3; Step=3 µm; Grid360x250
40
60
30
20
55
10
0.02
0.04
0.06
Zr content (wt%)
0.08
50
0.10
Fig.3. Recrystallized fraction and grain size
of AA 7150 Al alloy without pretreatment as a
function of Zr content.
(h)
=200 µm; Map3; Step=3 µm; Grid360x250
=200 µm; Map3; Step=3 µm; Grid360x250
50
46
44
46
40
40
30
20
17
18
9
10
9
2
0
3
2
2
0.09 Zr%
0.09 Zr%
0.04 Zr%
0.04 Zr%
Pretreated for 48h Pretreated for 72h Pretreated for 48h Pretreated for 72h
(a)
80
60
70
Without Pretreatment
Pretreated at 300 C
Pretreated at 400 C
100
84
82
72
72
55
52
50
52
40
25 26
20
23 22
50
46
46
40
44
40
30
20
17 18
9
10
9
2
0
0.04 Zr%
0.04 Zr%
0.09Zr%
0.09Zr%
Pretreated for 48h Pretreated for 72h Pretreated for 48h Pretreated for 72h
(b)
Fig.4. Recrystallized fraction and Recrystallized
grain size as a function of pretreaed temperature:
(a) recrystallied fraction; (b) recrystallized grain size.
120
Without Pretreatment
Pretreated for 48h
Pretreated for 72h
60
Recrystallized Fraction (%)
65
50
=200 µm; Map3; Step=3 µm; Grid341x260
=200 µm; Map3; Step=3 µm; Grid360x250
=200 µm; Map3; Step=3 µm; Grid360x250
Recrystallized Grainsize (m)
60
Without Pretreatment
Pretreated at 300 C
Pretreated at 400 C
60
Recrystallized Fraction (%)
70
70
Recrystallized Grain Size (m)
Recrystallized fraction
Recrystallized grain size
80
Recrystallized Fraction (%)
(g)
=200 µm; Map3; Step=3 µm; Grid357x250
120
70
75
90
0.00
(f)
(d)
Fig.2. Orientation map for AA 7150 Al alloy with pretreatment: (a), (b) AA 7150 Al alloy with 0.04 Zr%
pretreated at 300 ºC for 48 h and 72 h respectively; (c), (d) AA 7150 Al alloy with 0.04 Zr% pretreated at 400
ºC for 48 h and 72 h respectively; (e), (f) AA 7150 Al alloy with 0.09 Zr% pretreated at 300 ºC for 48 h and 72
h respectively; (g), (h) AA 7150 Al alloy with 0.09Zr% pretreated at 400 ºC for 48 h and 72 h respectively.
Fig.1. Orientation map for AA 7150 Al alloy
with different Zr content without pretreatment:
(a) without Zr; (b) 0.04 Zr %; (c) 0.09Zr %.
0
=200 µm; Map3; Step=3 µm; Grid346x210
Recrystallization
Analysis
470 ºc x 2 h
(c)
(b)
=200 µm; Map3; Step=3 µm; Grid340x230
=200 µm; Map3; Step=3 µm; Grid360x250
Solution Treatment
Temperature: 400 ºc
Strain Rate: 1 s-1
True Strain: 0.8
(a)
=200 µm; Map3; Step=3 µm; Grid360x250
(b)
Compression
Homogenization
0
2
3
2
0.09 Zr%
0.04 Zr%
0.04 Zr%
0.09 Zr%
Pretreated at 300 C Pretreated at 400 C Pretreated at 300 C Pretreated at 400 C
(a)
Recrystallized Grain Size (m)
Mg
Cu
Zr
Zhanying Guo
X.-Grant Chen
Chaire industrielle
de recherche
CRSNG/Rio Tinto Alcan
sur les nouvelles avenues en
métallurgie de la
transformation de l’aluminium
(CIMTAL)
Investigating static recrystaqllization behavior of AA 7150 aluminum
alloy with trace addition of Zr (ranging from 0.04 to 0.09 Zr wt.%).
Without Pretreatment
Pretreated for 48 h
Pretreated for 72 h
100
80
60
82 84
72
72
55
52
50
52
40
25 23
20
26
22
0
0.09 Zr %
0.09 Zr %
0.04 Zr %
0.04 Zr %
Pretreated at 300 C Pretreated at 400 C Pretreated at 300 C Pretreated at 400 C
(b)
Fig.4. Recrystallized fraction and Recrystallized grain
size of as a function of pretreaed holding time: (a)
recrystallied fraction; (b) rcrystallized grain size.
1. Both recrystallized fraction and recrystallized grain size, for AA 7150 Al alloy without pretreatment, decrease with the increase of Zr content.
2. When the alloy contains 0.04% Zr and is pretreated at 300 ºC, both recrystallized fraction and recrystallized grain size dramatically decrease,
compared to those without pretre