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The influence of thermomechanical parameters on the earing behaviour of 1050 and 1100 aluminium alloys
JournaloC
Materials Processing Technology ELSEVIER
Journal of Materials Processing Teclmology 63 (1997) 610·613
The Influence of Thennomechanical Parameters on the Earing Behaviour of 1050 and 1100 Aluminium Alloys
M JAHAZI andM GOUDARZI Department ofMaterials Eng., Tarbiat Modarres University, P.G. Box 14155-4838 Tehran/Islamic Republic ofIran
Abstract The effect of rolling and annealing parameters on the microstructure and earing of deep drawn Aluminium alloys in the range 0.5 to 3mm thicknesses was studied. 1100 and 1050 Aluminium alloy samples were taken from the mill at different stages of hot and cold rolling as well as at intermediate annealing steps. They were subsequently deep drawn and their earing measured. Also mechanical properties and microstructure of the samples were examined at each stage. The results indicated that by decreasing the finishing temperature the 0 and 90 0 earing diminishes while 45 0 earing increases. Also, under appropriate conditions a 1.4% 0 and 90 0 earing was measured on a 6 mm thick plate after hot rolling. The earing was reduced to about zero when the thickness was brought down to 4mm by cold rolling. For the thicknesses less than 1mm by applying an intermediate annealing at 350 °C an almost zero earing was obtained. Finally, it was observed that under all experimental conditions the earing is less for the 1050 alloy than for the 1100.
product. An additional aim was to compare the behaviour of 1050 and 1100 Aluminium alloys since these two alloys are commonly used for making cooking wares in Iran.
1. Introduction
Aluminium alloy sheet intended for use as cooking wares is subject to severe and conflicting property requirements which necessitate careful optimization of production parameters. As the final product must have high strength the sheet has a heavily cold rolled microstructure, but the latter produces strong 45 earing in deep drawn sheet. A low earing tendency which is necessary for a successful product can be achieved if a strong 0/90 earing is produced in the hot rolled product before cold rolling. It is well known that crystallographic texture is the principal cause of the directionality of properties commonly found in thermomechanically treated Aluminium alloys [1-5]. The 45 earing being the result of rolling texture consisting of the {110}<112> brass position, the intermediate S component and finally the {112}<111> copper orientation [2]. The 0/90 earing is mainly associated with the most familiar of all textures i.e. the {100}<001> cube texture and to some extent to the {11O}<001> Goss orientation [7]. If a sharp cube texture is present in the hot rolled band prior to cold rolling, it is possible by a judicious choice of thermomechanica1 parameters to achieve a minimum earing in the final sheet since the initial 0/90 earing gradually transforms to 45 type, and passes through a nearly zero earing condition at an appropriate cold reduction. The principal aim of this work was then to seek experimental conditions under which the 0/90 earing is maximized after hot rolling and annealing. The cold rolling conditions where adjusted such that a minimum earing was obtained on the final 0
0
0
0
0
0
0
0924-0136/97/$15.00 @ 1997 Elsevier Science SA All rights reserved PII S0924-0136(96)02693-3
2. Experimental Procedure and materials
The influences of chemical composition, hot rolling, intermediate annealing, cold rolling and [mal annealing on the earing behaviour were studied using a standard cup drawing test. Tensile test specimens in the 0, 45 0 and 90 0 to the rolling direction were prepared and tested according to the ASTMB577M-84 standard [8]. For each experimental condition the yield strength, percentage elongation and R-Values were measured. Finally, the microstructure of the samples was studied using optical microscopy. The starting materials were commercial 1050 and 1100 Aluminium alloys, having the compositions given in Table 1. Table 1. Chemical Compositions of alloys studied, Wt% alloy 1050 1100
Fe 0.24 0.35
Si 0.08 0.14
eu 0.10 0.08
AI Rem. Rem.
Slabs 300mm in thickness were used for the hot rolling experiments. A homogenization heat treatment at 450°C for 12 hours was applied before hot rolling. The latter was carried out
M. Jahazi. M. Goudarzi I Journal of Materials Processing Technology 63 (1997) 610-613
in a reversing mill where the thickness was reduced by 97 to 98% in 17 or 19 passes, the final thickness being between 8.5 to 6.5mm respectively. Final rolling temperature, as measured immediately after rolling was 230±1O°C. Intermediate annealing temperatures between 280 to 400°C and final annealing temperatures (i.e. on the cold rolled product) between 200 to 400°C were employed. The cold rolling experiments were carried out on 75x200x300 mm billets in a 34 ton experimental rolling mill where in some cases thickness reductions down to 94% were applied.
~
611
r;======::;;;============::;::======::;1
15
-k2 hours
0
0:: 0/90
----
1 hour
L5 W
0
(!)
« I-
-5
Z W
U 45°
0::: W
-15
....J
L..-
a.
300
280
320
340
360
380
400
3. Results and Discussion
ANNEALING TEMPERATURE, DC
3.1. Hot rolling
After hot rolling, the bands were normally in an unrecrystallized or only very slightly recrystallized state and generally showed an elongated and deformed microstructure. The influence of the amount of total reduction on the earing is shown in Fig.l.
1.0,-------------------, 0.9 0.8
" Z
i:i:
i1i
Co
23
0.7 0.6 0.5
0.4 0.3 0.2
01 0.01.-------------------' 97.0 97.2 97.4 97.6 97.8 98.0
PERCENT HOT REDUCTION Fig. 1. Percentage earing measured on hot rolled sheets.
It can be seen that by increasing the amount of reduction the tendency to have 0/90° earing decreases and 45° earing increases. This behaviour is expected to be associated with a decreasing proportion of the cube texture. Infact, when higher reductions are given, because of the time interval required to give this deformation the finish rolling temperatures fall to lower values. Consequently, the resulting microstructure is composed of more elongated deformed grains and much less recrystallized ones. Such a microstructure provides much less impetus toward 0/90 earing behaviour as fewer cube oriented grains are present in the material [9].
Fig. 2.
A comparison between Figs. 1 and 2 shows that after 1 hour annealing at 280°C the sample presents noticeable 45" earing while after 97.5% hot reduction 0/90° earing is still measurable, indicating that some recrystallized grains are present in the hot rolled band. Increasing the temperature from 280 to 300 and 320°C shows a decrease in 45° earing, suggesting that even recovery or a fairly small amount of recrystallizaion has a significant influence on the earing behaviour. As recrystallization proceeds so do the 0/90° earing indicating that cube oriented grains are more and more present in the material. An almost zero earing was also measured at 340°C which is expected to be the recrystallization temperature for this alloy. The influence of annealing time is also shown in Fig.2. It can be seen that under these conditions the zero earing occurs at 320°C demonstrating that recrystallization takes place at lower temperatures. The effect of various amounts of cold working after one hour annealing at different temperatures is shown in Fig.3.
~
Figure 2 shows the influences of annealing time and temperature on the earing behaviour of 7.5 mm thick sheets (i.e. 97.5% hot reduction) 60% cold rolled prior to annealing and 33% after it, reaching a [mal thickness of2.5 mm before deep drawing. The microstructure before annealing was heavily deformed resulting on 45° earing on the cold rolled product.
15
Z
i:i: 0/90
rr===ijr====~====~===;-,
0
« W
5
W ~
o
Z
-5
~
--II-
--.-
16% Red.
33% Red.
W (J
0:::
3.2. Intermediate annealing
Percentage earing measured on sheets annealed for different times before cold rolling.
45"
W
a.
-15
...J
L..-
280
300
320
340
360
380
400
ANNEALING TEMPERATURE, DC Fig. 3.
Percentage earing measured on sheets annealed at various temperatures before cold rolling to different reductions.
M. Jahazi. M. Goudarzi / Journal of Materials Processing Technology 63 (1997) 610-613
612
As expected, increasing cold rolling reduction at all temperatures caused a transition from 0/90° earing to 45° earing. However, this transition is slower when low annealing temperatures and cold reductions are used simultaneously. Infact, a comparison between the results obtained at 300° and 400°C for 16 and 33% reductions shows that the variation in percent earing is stronger at 400°C than at 300°C, which indicates that the cube texture produced during recrsytallization at 400°C is fairly stable during subsequent rolling.
3.4. Chemical composition
The variations of percent earing for 1050 and 1100 Aluminium alloys for various annealing temperatures are shown in Fig. 5.
Z
~ 0/90
1050
0
3.3. Cold rolling and final annealing
Samples 7.5 mm thick were cold rolled down to 2.5, 2 and 1.5 mm thicknesses and then annealed between 200 to 450°C for 15,45,60 and 120 minutes. The evolution of percent earing for 2mm thick samples (73% reduction) is shown in Fig. 4.
C)
15
Z
Ci: 0/90° e:(
W
5
W C)
0
~
Z
W
(J
0:::
w a.
--.- -.-
---
15 Min.
45 Min.
60 Min.
250
300
350
400
450
0
ANNEALING TEMPERATURE, C
Fig.
0
Z
1100
-5
~ 45° w a. -15
c::
200
250
300
350
400
ANNEALING TEMPERATURE,
450
°c
Fig. 5. Percentage earing measured for 1050 and 1100 alloys.
45° 200
5
W C)
-+120 Min.
-5
-15
W
j::
--.-
---
15
C)
4. Percentage earing measured on sheets 70% cold rolled and annealed at different temperatures for various times.
A transition from 4SO to 0/90° earing is observed with increasing the annealing temperature or the holding time in spite of the fact that in some areas the conditions are not favorable for recrystallization and only recovery is present. This confirms our previous [mding that even recovery can affect seriously the evolution of earing. Such influence of recovery on earing has also been reported by other workers [9]. However in the lower temperature range (200, 250°C) the variations in percent earing with holding time (Llli) are not very sharp indicating the lower sensitivity of the rolling texture to time rather than to temperature. As the recrystallization range is approached the four curves become parallel to each other and Llli remains almost constant for each temperature. This probably indicates that large volumes of the deformed matrix should have almost the same orientation leading to the nucleation of grains with similar recrystallization orientations. It is also worth noting that an almost zero earing is obtained on samples annealed for 15 minutes at 450°C while the same situation is obtained for 60 minutes at 350° and 120 minutes at 320°C. These data are important form the industrial point of view as they determine the quality of the final product.
As it can be seen, under similar experimental conditions the 1100 alloy keeps the rolling texture for longer times than the 1050 alloy. It seems then the lower iron and silicon contents in the 1050 alloy have favored the 0/90° earing. In fact it was reported that very small amounts of iron in solid solution have a great effect in reducing the recrystallization kinetics influencing by this way the texture evolution [10-12]. On the other hand, silicon when present in the alloy combines with iron in AlFeSi second phases during the annealing stage reducing by this way the amount of iron in solid solution. The size distribution of these second phase particles plays an important role in controlling the extent of the recrystallization process [13]. It was reported that the presence of second phase particles of size greater than 1 micron diminishes the 0/90° earing tendency [9,14]. As the frequency and size distribution of such particles increases in proportion to the content of iron and silicon in the alloy, the higher amounts of iron and silicon in the 1100 alloy favors the formation of larger particles resulting on the nucleation of new grains around them with different orientations from the cube texture [14]. Conclusions 1. Decreasing the finishing temperature diminishes the 0/90° earing in expense of 45° earing, 2. A transition from 45° to 0/90° earing is observed with increasing the annealing temperature or the holding time. 3. Under appropriate conditions determined in this investigation it is possible to obtain zero earing on 1.4 or 6 mm thick sheets.
References [1] J. Grewen and M. Heimendahl, Z. Metallkd, 59 (1968) 205. [2] R.T. Thorley and G.E.G. Tucker, J. [nst. Met., 86 (1957) 353.
M. Jahazi, M. Goudarzi / Journal of Materials Processing Technology 63 (1997) 610-613
[3] [4] [5] [6]
J. Grewen, Z. Metallkd, 59 (1968) 236. J. C. Blade,J. Inst. Met., 90 (1961) 374. W. Bunk and P. Esslinger, Z. Metallkd., 50 (1959) 278. G.J. Davis ,J.S. Kallend and T. Ruberg, Proc. 3rd European Colloquium on Textures (ed R. Penelle), Pont a Mousson, (1973) 299. [7] W.E. Hutchinson and H.E. Ekstrom, J. Mat. Sci. Tech., 6 (1990) 1103. [8] J.C. Wright, J. Inst. Met., 93 (1990) 289. [9] A. Oscarsson, W. B. Hutchinson, and H-E. Ekstrom, Mat. Sci. tech., 7 (1991) 554
[10] [11] [12] [13] [14]
613
K. Ito, R. Musick, and K. Lucke, Acta. Met., 31 (1983) 2137. K. Ito, K. Lucke and R. Rixen, Z. Metallkd, 67 (1976) 338. K. Ito, F. Seki, H. Abe, and K. Lucke, Z. Metallkd, 74 (1983) 772. E. Nes, Proc. Microstructural Control in Aluminium Alloys (ed. E. H. Chia et al) AIME New York, (1985) 95. J. Humphreys , Proc. Recrystallization and Grain Growth in Multiphase and Particle Containing Materials, (ed. N. Hansen et al.) Roskilde, Denmark, Ris0 National Laboratory, (1980) 35.
Materials Processing Technology ELSEVIER
Journal of Materials Processing Teclmology 63 (1997) 610·613
The Influence of Thennomechanical Parameters on the Earing Behaviour of 1050 and 1100 Aluminium Alloys
M JAHAZI andM GOUDARZI Department ofMaterials Eng., Tarbiat Modarres University, P.G. Box 14155-4838 Tehran/Islamic Republic ofIran
Abstract The effect of rolling and annealing parameters on the microstructure and earing of deep drawn Aluminium alloys in the range 0.5 to 3mm thicknesses was studied. 1100 and 1050 Aluminium alloy samples were taken from the mill at different stages of hot and cold rolling as well as at intermediate annealing steps. They were subsequently deep drawn and their earing measured. Also mechanical properties and microstructure of the samples were examined at each stage. The results indicated that by decreasing the finishing temperature the 0 and 90 0 earing diminishes while 45 0 earing increases. Also, under appropriate conditions a 1.4% 0 and 90 0 earing was measured on a 6 mm thick plate after hot rolling. The earing was reduced to about zero when the thickness was brought down to 4mm by cold rolling. For the thicknesses less than 1mm by applying an intermediate annealing at 350 °C an almost zero earing was obtained. Finally, it was observed that under all experimental conditions the earing is less for the 1050 alloy than for the 1100.
product. An additional aim was to compare the behaviour of 1050 and 1100 Aluminium alloys since these two alloys are commonly used for making cooking wares in Iran.
1. Introduction
Aluminium alloy sheet intended for use as cooking wares is subject to severe and conflicting property requirements which necessitate careful optimization of production parameters. As the final product must have high strength the sheet has a heavily cold rolled microstructure, but the latter produces strong 45 earing in deep drawn sheet. A low earing tendency which is necessary for a successful product can be achieved if a strong 0/90 earing is produced in the hot rolled product before cold rolling. It is well known that crystallographic texture is the principal cause of the directionality of properties commonly found in thermomechanically treated Aluminium alloys [1-5]. The 45 earing being the result of rolling texture consisting of the {110}<112> brass position, the intermediate S component and finally the {112}<111> copper orientation [2]. The 0/90 earing is mainly associated with the most familiar of all textures i.e. the {100}<001> cube texture and to some extent to the {11O}<001> Goss orientation [7]. If a sharp cube texture is present in the hot rolled band prior to cold rolling, it is possible by a judicious choice of thermomechanica1 parameters to achieve a minimum earing in the final sheet since the initial 0/90 earing gradually transforms to 45 type, and passes through a nearly zero earing condition at an appropriate cold reduction. The principal aim of this work was then to seek experimental conditions under which the 0/90 earing is maximized after hot rolling and annealing. The cold rolling conditions where adjusted such that a minimum earing was obtained on the final 0
0
0
0
0
0
0
0924-0136/97/$15.00 @ 1997 Elsevier Science SA All rights reserved PII S0924-0136(96)02693-3
2. Experimental Procedure and materials
The influences of chemical composition, hot rolling, intermediate annealing, cold rolling and [mal annealing on the earing behaviour were studied using a standard cup drawing test. Tensile test specimens in the 0, 45 0 and 90 0 to the rolling direction were prepared and tested according to the ASTMB577M-84 standard [8]. For each experimental condition the yield strength, percentage elongation and R-Values were measured. Finally, the microstructure of the samples was studied using optical microscopy. The starting materials were commercial 1050 and 1100 Aluminium alloys, having the compositions given in Table 1. Table 1. Chemical Compositions of alloys studied, Wt% alloy 1050 1100
Fe 0.24 0.35
Si 0.08 0.14
eu 0.10 0.08
AI Rem. Rem.
Slabs 300mm in thickness were used for the hot rolling experiments. A homogenization heat treatment at 450°C for 12 hours was applied before hot rolling. The latter was carried out
M. Jahazi. M. Goudarzi I Journal of Materials Processing Technology 63 (1997) 610-613
in a reversing mill where the thickness was reduced by 97 to 98% in 17 or 19 passes, the final thickness being between 8.5 to 6.5mm respectively. Final rolling temperature, as measured immediately after rolling was 230±1O°C. Intermediate annealing temperatures between 280 to 400°C and final annealing temperatures (i.e. on the cold rolled product) between 200 to 400°C were employed. The cold rolling experiments were carried out on 75x200x300 mm billets in a 34 ton experimental rolling mill where in some cases thickness reductions down to 94% were applied.
~
611
r;======::;;;============::;::======::;1
15
-k2 hours
0
0:: 0/90
----
1 hour
L5 W
0
(!)
« I-
-5
Z W
U 45°
0::: W
-15
....J
L..-
a.
300
280
320
340
360
380
400
3. Results and Discussion
ANNEALING TEMPERATURE, DC
3.1. Hot rolling
After hot rolling, the bands were normally in an unrecrystallized or only very slightly recrystallized state and generally showed an elongated and deformed microstructure. The influence of the amount of total reduction on the earing is shown in Fig.l.
1.0,-------------------, 0.9 0.8
" Z
i:i:
i1i
Co
23
0.7 0.6 0.5
0.4 0.3 0.2
01 0.01.-------------------' 97.0 97.2 97.4 97.6 97.8 98.0
PERCENT HOT REDUCTION Fig. 1. Percentage earing measured on hot rolled sheets.
It can be seen that by increasing the amount of reduction the tendency to have 0/90° earing decreases and 45° earing increases. This behaviour is expected to be associated with a decreasing proportion of the cube texture. Infact, when higher reductions are given, because of the time interval required to give this deformation the finish rolling temperatures fall to lower values. Consequently, the resulting microstructure is composed of more elongated deformed grains and much less recrystallized ones. Such a microstructure provides much less impetus toward 0/90 earing behaviour as fewer cube oriented grains are present in the material [9].
Fig. 2.
A comparison between Figs. 1 and 2 shows that after 1 hour annealing at 280°C the sample presents noticeable 45" earing while after 97.5% hot reduction 0/90° earing is still measurable, indicating that some recrystallized grains are present in the hot rolled band. Increasing the temperature from 280 to 300 and 320°C shows a decrease in 45° earing, suggesting that even recovery or a fairly small amount of recrystallizaion has a significant influence on the earing behaviour. As recrystallization proceeds so do the 0/90° earing indicating that cube oriented grains are more and more present in the material. An almost zero earing was also measured at 340°C which is expected to be the recrystallization temperature for this alloy. The influence of annealing time is also shown in Fig.2. It can be seen that under these conditions the zero earing occurs at 320°C demonstrating that recrystallization takes place at lower temperatures. The effect of various amounts of cold working after one hour annealing at different temperatures is shown in Fig.3.
~
Figure 2 shows the influences of annealing time and temperature on the earing behaviour of 7.5 mm thick sheets (i.e. 97.5% hot reduction) 60% cold rolled prior to annealing and 33% after it, reaching a [mal thickness of2.5 mm before deep drawing. The microstructure before annealing was heavily deformed resulting on 45° earing on the cold rolled product.
15
Z
i:i: 0/90
rr===ijr====~====~===;-,
0
« W
5
W ~
o
Z
-5
~
--II-
--.-
16% Red.
33% Red.
W (J
0:::
3.2. Intermediate annealing
Percentage earing measured on sheets annealed for different times before cold rolling.
45"
W
a.
-15
...J
L..-
280
300
320
340
360
380
400
ANNEALING TEMPERATURE, DC Fig. 3.
Percentage earing measured on sheets annealed at various temperatures before cold rolling to different reductions.
M. Jahazi. M. Goudarzi / Journal of Materials Processing Technology 63 (1997) 610-613
612
As expected, increasing cold rolling reduction at all temperatures caused a transition from 0/90° earing to 45° earing. However, this transition is slower when low annealing temperatures and cold reductions are used simultaneously. Infact, a comparison between the results obtained at 300° and 400°C for 16 and 33% reductions shows that the variation in percent earing is stronger at 400°C than at 300°C, which indicates that the cube texture produced during recrsytallization at 400°C is fairly stable during subsequent rolling.
3.4. Chemical composition
The variations of percent earing for 1050 and 1100 Aluminium alloys for various annealing temperatures are shown in Fig. 5.
Z
~ 0/90
1050
0
3.3. Cold rolling and final annealing
Samples 7.5 mm thick were cold rolled down to 2.5, 2 and 1.5 mm thicknesses and then annealed between 200 to 450°C for 15,45,60 and 120 minutes. The evolution of percent earing for 2mm thick samples (73% reduction) is shown in Fig. 4.
C)
15
Z
Ci: 0/90° e:(
W
5
W C)
0
~
Z
W
(J
0:::
w a.
--.- -.-
---
15 Min.
45 Min.
60 Min.
250
300
350
400
450
0
ANNEALING TEMPERATURE, C
Fig.
0
Z
1100
-5
~ 45° w a. -15
c::
200
250
300
350
400
ANNEALING TEMPERATURE,
450
°c
Fig. 5. Percentage earing measured for 1050 and 1100 alloys.
45° 200
5
W C)
-+120 Min.
-5
-15
W
j::
--.-
---
15
C)
4. Percentage earing measured on sheets 70% cold rolled and annealed at different temperatures for various times.
A transition from 4SO to 0/90° earing is observed with increasing the annealing temperature or the holding time in spite of the fact that in some areas the conditions are not favorable for recrystallization and only recovery is present. This confirms our previous [mding that even recovery can affect seriously the evolution of earing. Such influence of recovery on earing has also been reported by other workers [9]. However in the lower temperature range (200, 250°C) the variations in percent earing with holding time (Llli) are not very sharp indicating the lower sensitivity of the rolling texture to time rather than to temperature. As the recrystallization range is approached the four curves become parallel to each other and Llli remains almost constant for each temperature. This probably indicates that large volumes of the deformed matrix should have almost the same orientation leading to the nucleation of grains with similar recrystallization orientations. It is also worth noting that an almost zero earing is obtained on samples annealed for 15 minutes at 450°C while the same situation is obtained for 60 minutes at 350° and 120 minutes at 320°C. These data are important form the industrial point of view as they determine the quality of the final product.
As it can be seen, under similar experimental conditions the 1100 alloy keeps the rolling texture for longer times than the 1050 alloy. It seems then the lower iron and silicon contents in the 1050 alloy have favored the 0/90° earing. In fact it was reported that very small amounts of iron in solid solution have a great effect in reducing the recrystallization kinetics influencing by this way the texture evolution [10-12]. On the other hand, silicon when present in the alloy combines with iron in AlFeSi second phases during the annealing stage reducing by this way the amount of iron in solid solution. The size distribution of these second phase particles plays an important role in controlling the extent of the recrystallization process [13]. It was reported that the presence of second phase particles of size greater than 1 micron diminishes the 0/90° earing tendency [9,14]. As the frequency and size distribution of such particles increases in proportion to the content of iron and silicon in the alloy, the higher amounts of iron and silicon in the 1100 alloy favors the formation of larger particles resulting on the nucleation of new grains around them with different orientations from the cube texture [14]. Conclusions 1. Decreasing the finishing temperature diminishes the 0/90° earing in expense of 45° earing, 2. A transition from 45° to 0/90° earing is observed with increasing the annealing temperature or the holding time. 3. Under appropriate conditions determined in this investigation it is possible to obtain zero earing on 1.4 or 6 mm thick sheets.
References [1] J. Grewen and M. Heimendahl, Z. Metallkd, 59 (1968) 205. [2] R.T. Thorley and G.E.G. Tucker, J. [nst. Met., 86 (1957) 353.
M. Jahazi, M. Goudarzi / Journal of Materials Processing Technology 63 (1997) 610-613
[3] [4] [5] [6]
J. Grewen, Z. Metallkd, 59 (1968) 236. J. C. Blade,J. Inst. Met., 90 (1961) 374. W. Bunk and P. Esslinger, Z. Metallkd., 50 (1959) 278. G.J. Davis ,J.S. Kallend and T. Ruberg, Proc. 3rd European Colloquium on Textures (ed R. Penelle), Pont a Mousson, (1973) 299. [7] W.E. Hutchinson and H.E. Ekstrom, J. Mat. Sci. Tech., 6 (1990) 1103. [8] J.C. Wright, J. Inst. Met., 93 (1990) 289. [9] A. Oscarsson, W. B. Hutchinson, and H-E. Ekstrom, Mat. Sci. tech., 7 (1991) 554
[10] [11] [12] [13] [14]
613
K. Ito, R. Musick, and K. Lucke, Acta. Met., 31 (1983) 2137. K. Ito, K. Lucke and R. Rixen, Z. Metallkd, 67 (1976) 338. K. Ito, F. Seki, H. Abe, and K. Lucke, Z. Metallkd, 74 (1983) 772. E. Nes, Proc. Microstructural Control in Aluminium Alloys (ed. E. H. Chia et al) AIME New York, (1985) 95. J. Humphreys , Proc. Recrystallization and Grain Growth in Multiphase and Particle Containing Materials, (ed. N. Hansen et al.) Roskilde, Denmark, Ris0 National Laboratory, (1980) 35.