New Process Produces Superplastic Aerospace/Automotive Aluminum Alloy

Troeger, Lillianne P.; Starke, E.A.

doi:10.1002/1527-2648(200012)2:12<802::aid-adem802>3.0.co;2-y

Cited by 10 publications

(12 citation statements)

References 6 publications

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“…The reduction per ARB cycle is usually r ¼50%, which results in an equivalent strain of about 0.8/cycle. Aluminium and its alloys have great potential in automotive and aerospace industry applications due to their light-weight nature, good formability, good corrosion resistance and low cost [9][10][11]. However, the application is limited mostly due to their low strength compared with other metallic materials like steels.…”

Section: Introductionmentioning

confidence: 99%

Investigation of ultrafine grained AA1050 fabricated by accumulative roll bonding

Lü

et al. 2014

Materials Science and Engineering: A

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Accumulative roll bonding (ARB) is an effective method to produce ultrafine-grained (UFG) sheet materials with high strength. In this work, fully annealed AA1050 sheet with an initial thickness of 1.5. mm was processed by ARB up to five cycles. The microstructure was examined by optical microscopy (OM) and transmission electron microscopy (TEM). The results revealed that ARB is a promising process for fabricating ultrafine grained structures in aluminium sheets and the average grain size after 5-cycle ARB reached approximately 300. nm. Meanwhile, a remarkable enhancement in the strength was achieved and the value was about three times the strength of starting material. The microstructure at the bond interface introduced during ARB was investigated and its influence was discussed in detail. In addition, the microstructure and mechanical properties after ARB were compared with that after deformation by equal channel angular pressing (ECAP) up to the same strain. It has been found that ARB is more efficient in grain refinement and strengthening, which can be attributed to the different deformation modes of the two techniques. Accumulative roll bonding (ARB) is an effective method to produce ultrafine-grained (UFG) sheet materials with high strength. In this work, fully annealed AA1050 sheet with an initial thickness of 1.5 mm was processed by ARB up to five cycles. The microstructure was examined by optical microscopy (OM) and transmission electron microscopy (TEM). The results revealed that ARB is a promising process for fabricating ultrafine grained structures in aluminium sheets and the average grain size after 5-cycle ARB reached approximately 300 nm. Meanwhile, a remarkable enhancement in the strength was achieved and the value was about three times the strength of starting material. The microstructure at the bond interface introduced during ARB was investigated and its influence was discussed in detail. In addition, the microstructure and mechanical properties after ARB were compared with that after deformation by equal channel angular pressing (ECAP) up to the same strain. It has been found that ARB is more efficient in grain refinement and strengthening, which can be attributed to the different deformation modes of the two techniques.

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Section: Introductionmentioning

confidence: 99%

Investigation of ultrafine grained AA1050 fabricated by accumulative roll bonding

Lü

et al. 2014

Materials Science and Engineering: A

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“…There are two different TMP routes to achieve grain refinement in wrought aluminum alloys. One of these routes termed as overaging/recrystallization TMP, 1,[3][4][5][6] involves overaging treatment to produce coarse precipitate particles, which become sites for particle-stimulated nucleation of static recrystallization after cold rolling. The other route, which can be termed as recrystallization/recrystallization TMP, [7][8][9] involves two sequential procedures of warm/cold rolling followed by recrystallization annealing.…”

Section: Introductionmentioning

confidence: 99%

“…Second, aluminum alloys with initial unrecrystallized structure consisting of cells or recovered subgrains and containing fine dispersoids as Al 3 Zr are capable of superplasticity. 1,5,6) These aluminum alloys are subjected to extensive cold or warm rolling followed by heating to temperatures of superplastic deformation.…”

Section: Introductionmentioning

confidence: 99%

The Role of Grain Boundary Sliding in Microstructural Evolution during Superplastic Deformation of a 7055 Aluminum Alloy

et al. 2002

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The microstructure evolution in a 7055 aluminum alloy subjected to thermomechanical processing (TMP) was studied at 450 • C anḋ ε = 1.7 × 10 −3 s −1 at which the material exhibits superplastic behavior with a total elongation of 720% and the coefficient m = 0.58. Partially recrystallized initial structure of the as-processed 7055 Al consisted of bands of recrystallized grains with a mean size of 11 µm alternating with bands of recovered subgrains with a mean size of 2 µm. The true stress-true strain curve exhibits a well-defined peak stress, followed by gradual strain softening. The coefficient of strain rate sensitivity, m, remains unchanged at ε ≤ 1 and tends to decrease with strain at ε > 1. The initial microstructure persists near the peak strain. Following strain leads to evolution of initial partially recrystallized structure into uniform fully recrystallized structure due to occurrence of continuous dynamic reactions, i.e. continuous dynamic recrystallization (CDRX). The data of microstructural observation and misorientation analysis show that low-angle boundaries (LAB) gradually convert to high-angle boundaries (HAB) resulting in an extensive flow softening. It was shown that grain boundary sliding (GBS) provides superplastic flow at all strains. Concurrently, GBS plays an important role in the dynamic evolution of new grains facilitating conversion of LABs to HABs.

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“…[1][2][3][4] Commercial 6013 and 6066 alloys with standard chemical composition have been demonstrated to exhibit moderate superplastic properties [1][2][3] at T ≤ 540 • C. Fine grain structure was introduced in these materials by thermomechanical processing (TMP). 2,3) It was established that the low stability of fine grains in the 6XXX aluminum alloys under superplastic deformation limits ductility. 2,4) Recent work has demonstrated that it is possible to enhance superplastic ductilities of Al-Mg alloys subjected to TMP by minor alloying additives.…”

Section: Introductionmentioning

confidence: 99%

“…2,3) It was established that the low stability of fine grains in the 6XXX aluminum alloys under superplastic deformation limits ductility. 2,4) Recent work has demonstrated that it is possible to enhance superplastic ductilities of Al-Mg alloys subjected to TMP by minor alloying additives. 5,6) Additions of transition-element-dispersion particles in the aluminum alloys provide increased stability of fine grains under superplasticity that is extremely important for the manifestation of superior superplastic properties.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cu and Zr Additions on the Superplastic Behavior of 6061 Aluminum Alloy

et al. 2002

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Experiments were conducted to evaluate the influence of zirconium and copper additions on superplastic behavior of a 6061 aluminum alloy. Fine grains were produced in a commercial grade of 6061 Al and a 0.15%Zr + 0.7%Cu-modified 6061 alloy by two-step thermomechanical processing. The superplastic properties and microstructure evolution of both alloys were examined in tension at temperatures ranging from 475 to 620 • C and strain rates ranging from 7 × 10 −6 to 2.8 × 10 −2 s −1 . It was shown using differential thermal analysis that both alloys exhibit the highest superplastic characteristics in a partially melted state. The 0.15%Zr + 0.7%Cu-modified 6061 aluminum alloy exhibits a maximum elongation-to-failure of 1300% at 590 • C and an initial strain rate of 2.8 × 10 −4 s −1 . In contrast, the highest total elongation of 350% (m ∼ 0.6) was achieved in the commercial grade 6061 alloy at 600 • C and a strain rate of 1.4 × 10 −4 s −1 . The results suggest the addition of Zr provides high stability of the fine-grained structure under superplastic deformation at high temperatures by precipitation of Al 3 Zr dispersoids. Apparently, the increased amount of liquid phase caused by the copper addition can enhance the superplastic properties of the 6061 alloy.

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New Process Produces Superplastic Aerospace/Automotive Aluminum Alloy

Cited by 10 publications

References 6 publications

Investigation of ultrafine grained AA1050 fabricated by accumulative roll bonding

Investigation of ultrafine grained AA1050 fabricated by accumulative roll bonding

The Role of Grain Boundary Sliding in Microstructural Evolution during Superplastic Deformation of a 7055 Aluminum Alloy

Effect of Cu and Zr Additions on the Superplastic Behavior of 6061 Aluminum Alloy

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