Grain refinement of AZ31 and ZK60 Mg alloys — towards superplasticity studies

Bussiba, A.; Artzy, A. Ben; Shtechman, A.; Ifergan, S.; Kupiec, M.

doi:10.1016/s0921-5093(00)01354-x

Cited by 145 publications

(85 citation statements)

References 10 publications

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“…However, the stress concentration due to dislocation accumulation at the interfaces between the fine grains and coarse grains can still be relieved through grain rotation and grain growth of the fine grains. Hence the interface between the fine and coarse grains which is suggested as a possible site for cavity nucleation [32] does not appear to be true in the present material. It may be possible here that the stress relaxation process still remains active in the fine grain region of the bimodal structure to avoid cavitation.…”

Section: Interrelationship Between Grain Growth and Cavitationcontrasting

confidence: 59%

Effect of local strain distribution on concurrent microstructural evolution during superplastic deformation of Al–Li 8090 alloy

Pancholi¹,

Kashyap²

2003

Materials Science and Engineering: A

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Superplastic deformation of Al Á/Li 8090 alloy was carried out to study the effect of local strain developed on the microstructural variation along the gauge length of tensile specimens. For this, separate specimens were deformed to failure at a constant temperature of 530 8C and at the strain rates within the superplastic regime. The strain distribution was found to be non-uniform with more deformation towards fracture tip and less towards the shoulder section of specimens. The grain size was found to decrease with increase in local strain whereas cavity size and cavity volume fraction were found to increase. The cavity growth in longitudinal direction is suggested to be controlled by power law but the same in transverse direction is controlled by diffusional process. A model is proposed for cavity nucleation on the basis of inhomogeneity in microstructure and its implication in deformation mechanism.

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Section: Interrelationship Between Grain Growth and Cavitationcontrasting

confidence: 59%

Effect of local strain distribution on concurrent microstructural evolution during superplastic deformation of Al–Li 8090 alloy

Pancholi¹,

Kashyap²

2003

Materials Science and Engineering: A

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“…Thus, in As-received As-ECAE the investigated alloy, low temperature superplasticity occurs not only at low strain rate range but also at a relatively high strain rate of 1 Â 10 À3 s À1 compared to conventional low temperature superplastic materials. [15][16][17] In the specimens tested at 473 K and 523 K at the strain rate of 1 Â 10 À2 s À1 , large elongations of 242% and 398% are respectively obtained. That is, high strain rate superplasticity occurs at such relatively low temperatures.…”

Section: Microstructuresmentioning

confidence: 98%

Superplastic Deformation of AZ61 Magnesium Alloy having Fine Grains

et al. 2004

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Extruded Mg-6 mass%Al-1 mass%Zn (AZ61) alloy was grain-refined utilizing Equal Channel Angular Extrusion (ECAE) processing. Initially, the extruded bar of the alloy was ECAE-processed 2-times at 473 K. Subsequently, it was processed 4-times at 448 K. As a result, the grains are refined to less than 1 mm and a large amount of fine Mg 17 Al 12 compound precipitates. Subsequently, the superplastic properties of the ECAE-processed specimens were investigated. Large fracture elongations of over 300% are obtained at 423 K and 448 K, which is below T m =2 (T m : melting point of the alloy), at strain rates above 1 Â 10 À4 s À1 and 1 Â 10 À3 s À1 , respectively. That is, low temperature superplasticity occurs. Furthermore, at a high strain rate of 1 Â 10 À2 s À1 , superplasticity occurs with the elongation of 242% and 398% at relatively low temperatures of 473 K and 523 K, respectively. In the extraordinarily elongated specimens, significant grain boundary sliding is observed with strain rate sensitivity of 0:3$0:4. The activation energy for superplastic deformation is about 91 kJ/mol, which is close to that for grain boundary diffusion of pure magnesium. It is concluded that the superplastic deformation mechanism of the investigated alloy would be grain boundary sliding accommodated by dislocation slip controlled by grain boundary diffusion.

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“…However, remarkable improvements of ductility of magnesium alloys have been reported in samples that addition of lithium to magnesium 6,7) and have improved microstructure through grain refinement. [8][9][10] Also, magnesium alloys with controlled texture have been reported to exhibit improved ductility. [11][12][13] Previous researches 14,15) show that in magnesium alloys processed by Equal Channel Angular Extrusion (ECAE) 16) using specimens that have a small diameter of about 15 mm, the grains are refined and a texture in which the basal plane is inclined at 45 to the extrusion direction is obtained.…”

Section: Introductionmentioning

confidence: 99%

Microstructures and Tensile Properties of ECAE-Processed and Forged AZ31 Magnesium Alloy

et al. 2003

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In order to achieve same level of high strength and high ductility as 6061 aluminum forging alloy that is currently used for automobile applications, AZ31 magnesium alloy rod with a large diameter of 40 mm was subjected to ECAE-processing, and the microstructures and mechanical properties of the ECAE-processed specimens were investigated. Furthermore, automobile knuckle arm was produced by forging using the ECAE-processed material, and the mechanical properties of the forged product and their strain rate dependencies were investigated under impact tensile load conditions. 4pass-ECAE-processed specimen has fine and uniform microstructure and a texture whose basal planes are mainly parallel to the extrusion direction with some inclined at angles up to 45 to the extrusion direction. Therefore, they show high ductility even if the tensile direction is parallel to the extrusion direction. The knuckle arm forged using the ECAE-processed material exhibits high elongation even in the high strain rate region. Furthermore, the tensile strength, fracture elongation and absorption energy of the forged product increase with increasing strain rate and their values are higher than those of T6-treated 6061 aluminum forging alloy specified by JIS.

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Grain refinement of AZ31 and ZK60 Mg alloys — towards superplasticity studies

Cited by 145 publications

References 10 publications

Effect of local strain distribution on concurrent microstructural evolution during superplastic deformation of Al–Li 8090 alloy

Effect of local strain distribution on concurrent microstructural evolution during superplastic deformation of Al–Li 8090 alloy

Superplastic Deformation of AZ61 Magnesium Alloy having Fine Grains

Microstructures and Tensile Properties of ECAE-Processed and Forged AZ31 Magnesium Alloy

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