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Mechanical properties of aluminium alloys processed by SPD: Comparison of different alloy systems and possible product areas
Materials Science and Engineering A 410–411 (2005) 426–429
Mechanical properties of aluminium alloys processed by SPD: Comparison of different alloy systems and possible product areas Hans J. Roven a,∗ , Hakon Nesboe a , Jens C. Werenskiold a , Tanja Seibert b a b
The Norwegian University of Science and Technology, Department of Materials Technology, N-7491 Trondheim, Norway Friedrich-Alexander-Universit¨at Erlangen-N¨urnberg, Institut f¨ur Werkstoffwissenschaften, D-91058 Erlangen, Germany Received in revised form 4 May 2005
Abstract The mechanical properties of a wide range of aluminium alloys are compared after being subjected to severe plastic deformation (SPD), i.e. equal channel angular pressing (ECAP). Alloys involved are AlMg, AlMn, AlMgSi, and AlMgSc. The effect of SPD on mechanical properties is mostly beneficial with age-hardenable alloys, whereas non-age-hardenable alloys tend to be relatively less reacting to SPD as compared to conventional processing. Finally, some challenges in regard to commercialization will be discussed briefly. © 2005 Elsevier B.V. All rights reserved. Keywords: Aluminium alloys; SPD; Ultrafine grain; Mechanical properties
1. Introduction In recent years, attention has been drawn to the processing of submicron grained materials, e.g. [1–5]. A significant amount of works have been published in regard to the effect of SPD on mechanical properties of aluminium alloys, i.e. both non-agehardenable [6–8] and age-hardenable [9,10] alloy systems. The highest strength in ultrafine grained (UFG) aluminium so far is reported for a standard AlZnMg alloy, i.e. 650 and 720 MPa tensile yield and ultimate strength, respectively [11]. Generally, strength increase in combination with a reduction in ductility is typically observed after ECAP. However, recent work has shown that high strength and ductility combinations are achievable in age-hardening aluminium alloys processed in the solution heat treated condition followed by post-ECAP aging at ∼100 ◦ C [9,12]. Earlier work has shown that grain boundary sliding (GBS) can introduce super plasticity [13]. Mechanisms for good combinations of high strength and ductility have been suggested, e.g. due to bimodal grain size distributions [14] and re-arrangement (recovery) of dislocation structures [13]. In spite of the promising mechanical properties reported in the literature, conservatism and skepticism seem to domi∗
Corresponding author. Tel.: +47 73594966; fax: +47 73550203. E-mail address: [email protected] (H.J. Roven).
0921-5093/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2005.08.112
nate traditional industry. However, recent developments indicate increasing commercial interests [15]. 2. Experimental procedures Seven different aluminium alloys were subjected to ECAP by route A, i.e. see Table 1. The die had a channel intersection angle Φ = 90◦ and arc of curvature [16] Ψ = 20.6◦ and workpiece dimensions were 19.5 mm × 19.5 mm × 100 mm. The age-hardenable AlMgSi(Cu) alloys were received as cast billets, homogenized according to industrial standards, solid solution heat treated and kept in liquid nitrogen until ECAP and between passes (CCS: cryogenically cooled specimens). Nonage-hardenable alloys AlMn (3103) and AlMg (5182) were received in the hot-rolled and homogenized condition and subjected to ECAP at room temperature (RT), 5182 with inter-pass annealing (IA, 200 ◦ C/2 h). The experimental AlMgSc alloy was received in homogenized and hot extruded condition and was subjected to ECAP at RT. Vickers hardness tests were performed in the x-plane [17] and flat tensile specimens (25 mm gauge length, 10 mm width and 2 mm thickness) were machined from the y-plane [17] and tested at nominal strain rate ∼0.01 s−1 . One sample was tested for each condition, i.e. additional testing showed typical maximum variations ±2 MPa. Post-ECAP artificial aging treatments were conducted at temperatures ranging from 90 to 200 ◦ C.
H.J. Roven et al. / Materials Science and Engineering A 410–411 (2005) 426–429
427
Table 1 Chemical compositions (wt.%) of investigated materials Alloy system
Alloy
Fe
Si
Mg
Mn
Cu
Cr
Zr
Sc
Al
ECAP temperaturea
AlMn AlMg AlMgScb AlMgSi AlMgSi AlMgSi AlMgSiCuc
3103 5182 5xSc 6060 6005 6082 6xxx
0.60 0.30 0.20 0.19 0.20 0.20 0.20
– – – 0.60 0.80 1.00 0.96
– 4.00 5.10 0.74 0.56 0.64 0.70
1.10 0.35 0.40 0.03 0.47 0.52 0.60
– – – – – – 0.20
– – – 0.13 – – 0.20
– – 0.10 – – – –
– – 0.20 – – – –
Bal. Bal. Bal. Bal. Bal. Bal. Bal.
RT RT + IA RT CCS CCS CCS CCS
a b c
RT: room temperature, IA: interpass annealing 220 ◦ C for 2 h, CCS: cryogenically cooled specimens. Alloy AlMgSc is similar to the AlMg. AlMgSiCu is similar to alloy 6082.
3. Results
3.3. Artificial aging of SPD materials
3.1. Strength development during ECA pressing
Aging at temperatures 90–130 ◦ C increases the ductility whereas strength shows a minor reduction (Fig. 1a). Conventional artificial aging at 175 ◦ C shows rapid softening in the ECA pressed AlMgSi alloy (Fig. 1b), whereas aged at 110 ◦ C a classical age hardening behavior is seen (Fig. 1b). The hardness increase due to age hardening is low in materials subjected to ECAP—even at low aging temperatures (Fig. 1b). As expected, age hardening kinetics increases with increasing aging temperature and the number of ECAP passes.
All investigated alloys exhibit a significant hardness increase after the first ECAP pass. Beyond one pass the hardness increase is less pronounced. Among the non-age-hardenable alloys, the Sc-containing alloy (5xSc) achieves the highest hardness, whereas the AlMg alloy (inter-pass annealed) softens beyond six passes. For the age-hardenable alloys highest hardness values are obtained in the experimental alloy (6xxx) subjected to cryogenic cooling between passes.
4. Discussion
3.2. Comparison SPD versus conventional processing
4.1. Discussion of results
Firstly, it is obvious from the present comparison to conventional processing that SPD by ECAP for non-age-hardenable alloys is not very promising with regard to yield stress and tensile strength, as these alloys only exhibit minor improvements (Table 2). Secondly, age-hardenable AlMgSi alloys have a substantial increase in strength after SPD compared to conventional processing, i.e. ranging 18–36% and 16–28% for yield stress and tensile strength, respectively. Another observation is that the increase in tensile strength is less than for the yield stress, and this trend is more pronounced the lower the alloying contents.
A comparison of different alloys in regard to their response to SPD has not been studied to any great detail in the past, although an attempt based on literature data has been reported by Markushev and Murashkin [19]. This work claims that: (a) SPD of non-age-hardenable alloys does not result in noticeable improvement in strength compared to standard methods of work hardening, (b) SPD is efficient for improving strength in lowalloy age-hardenable alloys, but does not increase the strength in higher-alloyed age-hardenable alloys. The present tensile tests results (Table 2) clearly indicate that the strength increase as compared to conventional processing in non-age-hardenable alloys is very limited, in agreement to [19]. In contrast, age-
Fig. 1. (a) Effect of aging temperature on strength and ductility in AlMgSi alloy (6082) after N = 6 passes and subsequently aged to maximum hardness (143 HV) and (b) hardness evolution at 110 and 175 ◦ C after N = 0 and 6 passes.
H.J. Roven et al. / Materials Science and Engineering A 410–411 (2005) 426–429
428
Table 2 Mechanical properties after ECAP (N = number of passes) and comparison to conventionally processed materials (‘conv.’) Rp0.2 (MPa)
UTS (MPa)
Conv. H18 ECAP, N = 6
230 250
250 270
– 6
– +9% (8%)
5182
Conv. H19 ECAP, N = 3
395 430
420 470
– 8
– +9% (12%)
5xScc
ECAP, N = 1
417
472
7
+6% (12%)
6xxx
Cast T6 ECAP, N = 3d
110 ◦ C/16 h
330 410
360 426
7 18
– +24% (8%)e
6082
Conv. T6 ECAP, N = 6d
90 ◦ C/192 h
370 437
385 447
10 17
– +18% (16%)
6060
Conv. T6 ECAP, N = 9d
110 ◦ C/72 h
230 310
250 320
7 14
– +35% (28%)
6005
Conv. T6 ECAP, N = 7d
110 ◦ C/72 h
280 380
310 395
9 12
– +36% (27%)
Alloy
Processinga
3103
Aging conditions
δ (%)b
Increase in Rp0.2 (UTS)
Conventional data are taken from [18]. a ECAP using route A, N = number of passes. ε ∼ 1 for each pass. b Total fracture elongation. c Alloy with Sc is compared to the alloy 5182 (which is similar in composition), the latter in a H19 condition. d ECAP in room temperature die and specimens cooled to −196 ◦ C before and between passes. e Increase measured against cast material.
hardenable alloys are seen to be the most responding to SPD in the present work. Strength increase as compared to conventional processing can reach up to ∼40%, and at the same time ductility can be recovered and enters promising levels when aged at low temperatures, in agreement to Kim et al. [9] and Kim et al. [12]. Hence, the age-hardenable alloys benefit strongly from SPD and demonstrate highest strengthening potential, both in the present work (Table 2) and in the literature [11]. In the present work, the increase rate in yield stress versus alloying contents is highest below 2 wt.%, where the age-hardenable alloys are located (Fig. 2a). Although alloying range is limited, the strength of agehardenable alloys seems proportional to the alloying content, and non-age-hardenable alloys fall below a prediction line based on the former alloy type (Fig. 2b). A similar consideration of ductility against alloying content indicates a maximum around 2 wt.% when aged or annealed at around 100 ◦ C after ECAP, suggesting that precipitation and a mild recovery together with SPD
gives optimum strength combined with reasonable ductility in the age-hardenable alloys. 4.2. Commercialization and products The present investigation on aluminium alloys indicates that SPD can give rise to significantly improved mechanical properties in age-hardenable alloys. Three main challenges need to be overcome in order to be cost competitive, i.e. development of processes for ultra-high strains, robust up-scaled SPD forming equipment and processes which are continuous and have multiple shape possibilities. Also, further investigations in combination with special alloy design should address the temperature stability of SPD alloys and post-processing possibilities. However, the potentials for non-age-hardenable alloys in regard to mechanical properties are less since cost-effective commercial processes such as cold-rolling already benefits from highly
Fig. 2. Yield strength vs. amount of alloying elements. R2 = 1.0 indicates 100% match. (a) As-pressed condition, logarithmic curve fitting based on all alloys and (b) linear curve fitting based only on age-hardenable alloys (after aging).
H.J. Roven et al. / Materials Science and Engineering A 410–411 (2005) 426–429
deformed microstructures in solute-containing alloys. On the other hand, these alloys might have superior post-SPD forming characteristics. In general, aluminium alloys have large potential for super plastic forming [13], e.g. can be cost-effective and even superior today’s commercialized technology. Commercialization through today’s strong focus on nanotechnology is therefore likely [15]. 5. Conclusion The present observations may indicate that the effect of SPD on mechanical properties is mostly beneficial for age-hardenable alloys, whereas non-age-hardenable alloys tend to be relatively less reacting to SPD as compared to conventional processing. However, more work needs to explore the post-SPD processing opportunities, especially for the non-age-hardenable alloys. A widespread commercialization of SPD aluminium technology is likely. Acknowledgements The study was supported by the Norwegian Research Council (No. 162291/i40), Hydro Aluminium AS, Nammo AS and European Aeronautic Defence and Space Company (EADS). References [1] T.C. Lowe, R. Valiev (Eds.), NATO Advanced Research Workshop on Investigations and Applications on Severe Plastic Deformation, Moscow, Russia, August 2–7, 1999, Kluwer Academic Press, The Netherlands, 2000. [2] Y.T. Zhu, T.G. Langdon, R.S. Mishra, S.L. Semiatin, M.J. Saran, T.C. Lowe (Eds.), TMS Symposium: Ultrafine Grained Materials II, TMS, Warrendale, PA, USA, 2002.
429
[3] M. Zehetbauer, R.Z. Valiev (Eds.), Nanomaterials by Severe Plastic Deformation—NANOSPD2, Vienna, December 9–13, 2002, Wiley/VCH, Wainheim, Germany, 2004. [4] Y.T. Zhu, T.G. Langdon, R.Z. Valiev, S.L. Semiatin, D.H. Shin, T.C. Lowe (Eds.), TMS Symposium: Ultrafine Grained Materials III, TMS, Warrendale, PA, USA, 2004. [5] NATO Advanced Research Workshop: Nanostructured Materials by High Pressure Severe Plastic Deformation, Donetsk, Ukraine, September 22–26, 2004, Unpublished. [6] T. Mukai, M. Kawazoe, K. Higashi, Mater. Sci. Eng. A 247 (1998) 270–274. [7] Z.C. Wang, P.B. Prangnell, Mater. Sci. Eng. A 326 (2002) 87–97. [8] Z. Horita, T. Fujinami, M. Nemoto, T.G. Langdon, Metall. Mater. Trans. 31A (2000) 691–701. [9] J.K. Kim, H.G. Jeong, S.I. Hong, Y.S. Kim, W.J. Kim, Scripta Mater. 45 (2001) 901–907. [10] C. Xu, M. Furukawa, Z. Horita, T.G. Langdon, Acta Mater. 51 (2003) 6139–6149. [11] Y.H. Zhao, X.Z. Liao, Z. Jin, R.Z. Valiev, Y.T. Zhu, Acta Mater. 52 (2004) 4589–4599. [12] W.J. Kim, C.S. Chung, D.S. Ma, S.I. Hong, H.K. Kim, Scripta Mater. 49 (2003) 333–338. [13] R. Valiev, Nat. Mater. 3 (2004) 511–516. [14] Y. Wang, M. Chen, F. Zhou, E. Ma, Nature 419 (2002) 912–915. [15] T.C. Lowe, Y.T. Zhu, in: M. Zehetbauer, R.Z. Valiev (Eds.), Nanomaterials by Severe Plastic Deformation—NANOSPD2, Wiley/VCH, Weinheim, Germany, 2004, pp. 789–797. [16] Y. Iwahashi, J. Wang, Z. Horita, M. Nemoto, Scripta Mater. 35 (1996) 143–146. [17] M. Furukawa, Y. Iwahashi, Z. Horita, M. Nemoto, T.G. Langdon, Mater. Sci. Eng. A 257 (1998) 328–332. [18] Hydro Aluminium AS, Internal Data Sheets, Materials Technology R&D Centre Sunndalsora, Norway, 2004. [19] M.V. Markushev, M.Y. Murashkin, in: Y.T. Zhu, T.G. Langdon, R.S. Mishra, S.L. Semiatin, M.J. Saran, T.C. Lowe (Eds.), TMS Symposium: Ultrafine Grained Materials II, TMS, Warrendale, PA, USA, 2002, pp. 371–380.
Mechanical properties of aluminium alloys processed by SPD: Comparison of different alloy systems and possible product areas Hans J. Roven a,∗ , Hakon Nesboe a , Jens C. Werenskiold a , Tanja Seibert b a b
The Norwegian University of Science and Technology, Department of Materials Technology, N-7491 Trondheim, Norway Friedrich-Alexander-Universit¨at Erlangen-N¨urnberg, Institut f¨ur Werkstoffwissenschaften, D-91058 Erlangen, Germany Received in revised form 4 May 2005
Abstract The mechanical properties of a wide range of aluminium alloys are compared after being subjected to severe plastic deformation (SPD), i.e. equal channel angular pressing (ECAP). Alloys involved are AlMg, AlMn, AlMgSi, and AlMgSc. The effect of SPD on mechanical properties is mostly beneficial with age-hardenable alloys, whereas non-age-hardenable alloys tend to be relatively less reacting to SPD as compared to conventional processing. Finally, some challenges in regard to commercialization will be discussed briefly. © 2005 Elsevier B.V. All rights reserved. Keywords: Aluminium alloys; SPD; Ultrafine grain; Mechanical properties
1. Introduction In recent years, attention has been drawn to the processing of submicron grained materials, e.g. [1–5]. A significant amount of works have been published in regard to the effect of SPD on mechanical properties of aluminium alloys, i.e. both non-agehardenable [6–8] and age-hardenable [9,10] alloy systems. The highest strength in ultrafine grained (UFG) aluminium so far is reported for a standard AlZnMg alloy, i.e. 650 and 720 MPa tensile yield and ultimate strength, respectively [11]. Generally, strength increase in combination with a reduction in ductility is typically observed after ECAP. However, recent work has shown that high strength and ductility combinations are achievable in age-hardening aluminium alloys processed in the solution heat treated condition followed by post-ECAP aging at ∼100 ◦ C [9,12]. Earlier work has shown that grain boundary sliding (GBS) can introduce super plasticity [13]. Mechanisms for good combinations of high strength and ductility have been suggested, e.g. due to bimodal grain size distributions [14] and re-arrangement (recovery) of dislocation structures [13]. In spite of the promising mechanical properties reported in the literature, conservatism and skepticism seem to domi∗
Corresponding author. Tel.: +47 73594966; fax: +47 73550203. E-mail address: [email protected] (H.J. Roven).
0921-5093/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2005.08.112
nate traditional industry. However, recent developments indicate increasing commercial interests [15]. 2. Experimental procedures Seven different aluminium alloys were subjected to ECAP by route A, i.e. see Table 1. The die had a channel intersection angle Φ = 90◦ and arc of curvature [16] Ψ = 20.6◦ and workpiece dimensions were 19.5 mm × 19.5 mm × 100 mm. The age-hardenable AlMgSi(Cu) alloys were received as cast billets, homogenized according to industrial standards, solid solution heat treated and kept in liquid nitrogen until ECAP and between passes (CCS: cryogenically cooled specimens). Nonage-hardenable alloys AlMn (3103) and AlMg (5182) were received in the hot-rolled and homogenized condition and subjected to ECAP at room temperature (RT), 5182 with inter-pass annealing (IA, 200 ◦ C/2 h). The experimental AlMgSc alloy was received in homogenized and hot extruded condition and was subjected to ECAP at RT. Vickers hardness tests were performed in the x-plane [17] and flat tensile specimens (25 mm gauge length, 10 mm width and 2 mm thickness) were machined from the y-plane [17] and tested at nominal strain rate ∼0.01 s−1 . One sample was tested for each condition, i.e. additional testing showed typical maximum variations ±2 MPa. Post-ECAP artificial aging treatments were conducted at temperatures ranging from 90 to 200 ◦ C.
H.J. Roven et al. / Materials Science and Engineering A 410–411 (2005) 426–429
427
Table 1 Chemical compositions (wt.%) of investigated materials Alloy system
Alloy
Fe
Si
Mg
Mn
Cu
Cr
Zr
Sc
Al
ECAP temperaturea
AlMn AlMg AlMgScb AlMgSi AlMgSi AlMgSi AlMgSiCuc
3103 5182 5xSc 6060 6005 6082 6xxx
0.60 0.30 0.20 0.19 0.20 0.20 0.20
– – – 0.60 0.80 1.00 0.96
– 4.00 5.10 0.74 0.56 0.64 0.70
1.10 0.35 0.40 0.03 0.47 0.52 0.60
– – – – – – 0.20
– – – 0.13 – – 0.20
– – 0.10 – – – –
– – 0.20 – – – –
Bal. Bal. Bal. Bal. Bal. Bal. Bal.
RT RT + IA RT CCS CCS CCS CCS
a b c
RT: room temperature, IA: interpass annealing 220 ◦ C for 2 h, CCS: cryogenically cooled specimens. Alloy AlMgSc is similar to the AlMg. AlMgSiCu is similar to alloy 6082.
3. Results
3.3. Artificial aging of SPD materials
3.1. Strength development during ECA pressing
Aging at temperatures 90–130 ◦ C increases the ductility whereas strength shows a minor reduction (Fig. 1a). Conventional artificial aging at 175 ◦ C shows rapid softening in the ECA pressed AlMgSi alloy (Fig. 1b), whereas aged at 110 ◦ C a classical age hardening behavior is seen (Fig. 1b). The hardness increase due to age hardening is low in materials subjected to ECAP—even at low aging temperatures (Fig. 1b). As expected, age hardening kinetics increases with increasing aging temperature and the number of ECAP passes.
All investigated alloys exhibit a significant hardness increase after the first ECAP pass. Beyond one pass the hardness increase is less pronounced. Among the non-age-hardenable alloys, the Sc-containing alloy (5xSc) achieves the highest hardness, whereas the AlMg alloy (inter-pass annealed) softens beyond six passes. For the age-hardenable alloys highest hardness values are obtained in the experimental alloy (6xxx) subjected to cryogenic cooling between passes.
4. Discussion
3.2. Comparison SPD versus conventional processing
4.1. Discussion of results
Firstly, it is obvious from the present comparison to conventional processing that SPD by ECAP for non-age-hardenable alloys is not very promising with regard to yield stress and tensile strength, as these alloys only exhibit minor improvements (Table 2). Secondly, age-hardenable AlMgSi alloys have a substantial increase in strength after SPD compared to conventional processing, i.e. ranging 18–36% and 16–28% for yield stress and tensile strength, respectively. Another observation is that the increase in tensile strength is less than for the yield stress, and this trend is more pronounced the lower the alloying contents.
A comparison of different alloys in regard to their response to SPD has not been studied to any great detail in the past, although an attempt based on literature data has been reported by Markushev and Murashkin [19]. This work claims that: (a) SPD of non-age-hardenable alloys does not result in noticeable improvement in strength compared to standard methods of work hardening, (b) SPD is efficient for improving strength in lowalloy age-hardenable alloys, but does not increase the strength in higher-alloyed age-hardenable alloys. The present tensile tests results (Table 2) clearly indicate that the strength increase as compared to conventional processing in non-age-hardenable alloys is very limited, in agreement to [19]. In contrast, age-
Fig. 1. (a) Effect of aging temperature on strength and ductility in AlMgSi alloy (6082) after N = 6 passes and subsequently aged to maximum hardness (143 HV) and (b) hardness evolution at 110 and 175 ◦ C after N = 0 and 6 passes.
H.J. Roven et al. / Materials Science and Engineering A 410–411 (2005) 426–429
428
Table 2 Mechanical properties after ECAP (N = number of passes) and comparison to conventionally processed materials (‘conv.’) Rp0.2 (MPa)
UTS (MPa)
Conv. H18 ECAP, N = 6
230 250
250 270
– 6
– +9% (8%)
5182
Conv. H19 ECAP, N = 3
395 430
420 470
– 8
– +9% (12%)
5xScc
ECAP, N = 1
417
472
7
+6% (12%)
6xxx
Cast T6 ECAP, N = 3d
110 ◦ C/16 h
330 410
360 426
7 18
– +24% (8%)e
6082
Conv. T6 ECAP, N = 6d
90 ◦ C/192 h
370 437
385 447
10 17
– +18% (16%)
6060
Conv. T6 ECAP, N = 9d
110 ◦ C/72 h
230 310
250 320
7 14
– +35% (28%)
6005
Conv. T6 ECAP, N = 7d
110 ◦ C/72 h
280 380
310 395
9 12
– +36% (27%)
Alloy
Processinga
3103
Aging conditions
δ (%)b
Increase in Rp0.2 (UTS)
Conventional data are taken from [18]. a ECAP using route A, N = number of passes. ε ∼ 1 for each pass. b Total fracture elongation. c Alloy with Sc is compared to the alloy 5182 (which is similar in composition), the latter in a H19 condition. d ECAP in room temperature die and specimens cooled to −196 ◦ C before and between passes. e Increase measured against cast material.
hardenable alloys are seen to be the most responding to SPD in the present work. Strength increase as compared to conventional processing can reach up to ∼40%, and at the same time ductility can be recovered and enters promising levels when aged at low temperatures, in agreement to Kim et al. [9] and Kim et al. [12]. Hence, the age-hardenable alloys benefit strongly from SPD and demonstrate highest strengthening potential, both in the present work (Table 2) and in the literature [11]. In the present work, the increase rate in yield stress versus alloying contents is highest below 2 wt.%, where the age-hardenable alloys are located (Fig. 2a). Although alloying range is limited, the strength of agehardenable alloys seems proportional to the alloying content, and non-age-hardenable alloys fall below a prediction line based on the former alloy type (Fig. 2b). A similar consideration of ductility against alloying content indicates a maximum around 2 wt.% when aged or annealed at around 100 ◦ C after ECAP, suggesting that precipitation and a mild recovery together with SPD
gives optimum strength combined with reasonable ductility in the age-hardenable alloys. 4.2. Commercialization and products The present investigation on aluminium alloys indicates that SPD can give rise to significantly improved mechanical properties in age-hardenable alloys. Three main challenges need to be overcome in order to be cost competitive, i.e. development of processes for ultra-high strains, robust up-scaled SPD forming equipment and processes which are continuous and have multiple shape possibilities. Also, further investigations in combination with special alloy design should address the temperature stability of SPD alloys and post-processing possibilities. However, the potentials for non-age-hardenable alloys in regard to mechanical properties are less since cost-effective commercial processes such as cold-rolling already benefits from highly
Fig. 2. Yield strength vs. amount of alloying elements. R2 = 1.0 indicates 100% match. (a) As-pressed condition, logarithmic curve fitting based on all alloys and (b) linear curve fitting based only on age-hardenable alloys (after aging).
H.J. Roven et al. / Materials Science and Engineering A 410–411 (2005) 426–429
deformed microstructures in solute-containing alloys. On the other hand, these alloys might have superior post-SPD forming characteristics. In general, aluminium alloys have large potential for super plastic forming [13], e.g. can be cost-effective and even superior today’s commercialized technology. Commercialization through today’s strong focus on nanotechnology is therefore likely [15]. 5. Conclusion The present observations may indicate that the effect of SPD on mechanical properties is mostly beneficial for age-hardenable alloys, whereas non-age-hardenable alloys tend to be relatively less reacting to SPD as compared to conventional processing. However, more work needs to explore the post-SPD processing opportunities, especially for the non-age-hardenable alloys. A widespread commercialization of SPD aluminium technology is likely. Acknowledgements The study was supported by the Norwegian Research Council (No. 162291/i40), Hydro Aluminium AS, Nammo AS and European Aeronautic Defence and Space Company (EADS). References [1] T.C. Lowe, R. Valiev (Eds.), NATO Advanced Research Workshop on Investigations and Applications on Severe Plastic Deformation, Moscow, Russia, August 2–7, 1999, Kluwer Academic Press, The Netherlands, 2000. [2] Y.T. Zhu, T.G. Langdon, R.S. Mishra, S.L. Semiatin, M.J. Saran, T.C. Lowe (Eds.), TMS Symposium: Ultrafine Grained Materials II, TMS, Warrendale, PA, USA, 2002.
429
[3] M. Zehetbauer, R.Z. Valiev (Eds.), Nanomaterials by Severe Plastic Deformation—NANOSPD2, Vienna, December 9–13, 2002, Wiley/VCH, Wainheim, Germany, 2004. [4] Y.T. Zhu, T.G. Langdon, R.Z. Valiev, S.L. Semiatin, D.H. Shin, T.C. Lowe (Eds.), TMS Symposium: Ultrafine Grained Materials III, TMS, Warrendale, PA, USA, 2004. [5] NATO Advanced Research Workshop: Nanostructured Materials by High Pressure Severe Plastic Deformation, Donetsk, Ukraine, September 22–26, 2004, Unpublished. [6] T. Mukai, M. Kawazoe, K. Higashi, Mater. Sci. Eng. A 247 (1998) 270–274. [7] Z.C. Wang, P.B. Prangnell, Mater. Sci. Eng. A 326 (2002) 87–97. [8] Z. Horita, T. Fujinami, M. Nemoto, T.G. Langdon, Metall. Mater. Trans. 31A (2000) 691–701. [9] J.K. Kim, H.G. Jeong, S.I. Hong, Y.S. Kim, W.J. Kim, Scripta Mater. 45 (2001) 901–907. [10] C. Xu, M. Furukawa, Z. Horita, T.G. Langdon, Acta Mater. 51 (2003) 6139–6149. [11] Y.H. Zhao, X.Z. Liao, Z. Jin, R.Z. Valiev, Y.T. Zhu, Acta Mater. 52 (2004) 4589–4599. [12] W.J. Kim, C.S. Chung, D.S. Ma, S.I. Hong, H.K. Kim, Scripta Mater. 49 (2003) 333–338. [13] R. Valiev, Nat. Mater. 3 (2004) 511–516. [14] Y. Wang, M. Chen, F. Zhou, E. Ma, Nature 419 (2002) 912–915. [15] T.C. Lowe, Y.T. Zhu, in: M. Zehetbauer, R.Z. Valiev (Eds.), Nanomaterials by Severe Plastic Deformation—NANOSPD2, Wiley/VCH, Weinheim, Germany, 2004, pp. 789–797. [16] Y. Iwahashi, J. Wang, Z. Horita, M. Nemoto, Scripta Mater. 35 (1996) 143–146. [17] M. Furukawa, Y. Iwahashi, Z. Horita, M. Nemoto, T.G. Langdon, Mater. Sci. Eng. A 257 (1998) 328–332. [18] Hydro Aluminium AS, Internal Data Sheets, Materials Technology R&D Centre Sunndalsora, Norway, 2004. [19] M.V. Markushev, M.Y. Murashkin, in: Y.T. Zhu, T.G. Langdon, R.S. Mishra, S.L. Semiatin, M.J. Saran, T.C. Lowe (Eds.), TMS Symposium: Ultrafine Grained Materials II, TMS, Warrendale, PA, USA, 2002, pp. 371–380.