Superplasticity and grain boundary sliding characteristics in two stage deformation of Mg–3Al–1Zn alloy sheet

Tan, J.C.; Tan, Ming Jen

doi:10.1016/s0921-5093(02)00097-7

Cited by 110 publications

(37 citation statements)

References 20 publications

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“…Wu and Liu [17] reported that even large grained AZ31 exhibits superplastic deformation when deformed at 500 °C due to the occurrence of DRX in the initial stages of deformation resulting in a stable fine grain size. Alternately, Tan and Tan [18] reported a two stage method of first refining the grain size by a lower temperature (250 °C) deformation and then by deforming at much higher temperatures (400 °C or 450 °C). In both the above methods, not only does the grain size change but also the texture, both of which influence the response to hot deformation [10].…”

Section: Introductionmentioning

confidence: 99%

Hot Deformation Mechanisms in AZ31 Magnesium Alloy Extruded at Different Temperatures: Impact of Texture

Rao

Prasad²,

Dzwonczyk

et al. 2012

Metals

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Abstract:The hot deformation characteristics of AZ31 magnesium alloy rod extruded at temperatures of 300 °C, 350 °C and 450 °C have been studied in compression. The extruded material had a fiber texture with > < 0 1 10 parallel to the extrusion axis. When extruded at 450 °C, the texture was less intense and the > < 0 1 10 direction moved away from the extrusion axis. The processing maps for the material extruded at 300 °C and 350 °C are qualitatively similar to the material with near-random texture (cast-homogenized) and exhibited three dynamic recrystallization (DRX) domains. In domains #1 and #2, prismatic slip is the dominant process and DRX is controlled by lattice self-diffusion and grain boundary self-diffusion, respectively. In domain #3, pyramidal slip occurs extensively and DRX is controlled by cross-slip on pyramidal slip systems. The material extruded at 450 °C exhibited two domains similar to #1 and #2 above, which moved to higher temperatures, but domain #3 is absent. The results are interpreted in terms of the changes in > < 0 1 10 fiber texture with extrusion temperature. Highly intense > < 0 1 10 texture, as in the rod extruded at 350 °C, will enhance the occurrence of prismatic slip in domains #1 and #2 and promotes pyramidal slip at temperatures >450 °C (domain #3).

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Section: Introductionmentioning

confidence: 99%

Hot Deformation Mechanisms in AZ31 Magnesium Alloy Extruded at Different Temperatures: Impact of Texture

Rao

Prasad²,

Dzwonczyk

et al. 2012

Metals

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“…At higher temperatures, additional slip systems are activated to enhance flow. [3,4] Superplasticity has also been reported at high temperatures and low strain rates for coarse-grained Mg alloys, [5,6] but surface oxidation can be severe at elevated temperatures, thus increasing the time and cost associated with cleaning operation, and complicating part manufacturing process. Therefore, warm forming of Mg at low levels of elevated temperature (£250°C) is a desirable goal.…”

Section: Introductionmentioning

confidence: 99%

Formability of Ultrafine-Grain Mg Alloy AZ31B at Warm Temperatures

Yang

Ghosh

2008

Metall Mater Trans A

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Warm formability of ultrafine-grain (UFG) AZ31B Mg alloy in the range of 150°C to 311°C is investigated. Refinement of grain size significantly improves the formability primarily through increasing strain rate sensitivity of flow stress and increasing diffuse quasi-stable flow, as compared with the coarse-grain AZ31B alloy. Strain rate sensitivity increases with increasing temperatures, and seems to be connected with dynamic recovery and grain boundary processes. For fine-grain sizes, twinning is inhibited. At 200°C and strain rates below 2 9 10 -4 s -1 , the UFG AZ31B alloy demonstrates a high rate of strain hardening up to a true strain of 0.6, in addition to its high strain rate sensitivity, which is responsible for its enhanced formability. Examination of the microstructure shows that there is competition between dynamic grain growth and grain refinement during deformation at modest warm forming temperatures, the former causing hardening and the latter causing softening. Increasing the test strain rate and starting with larger grain size initiates deformation twinning during forming, and assists in the refinement of the coarser grains followed by recrystallization.

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“…[11] Inspection of available data in Mg alloys reveals several inconsistencies. [12][13][14][15][16][17][18][19][20][21] For example, measurements reported in relatively coarse-grained Mg alloys, with d > 75 lm, under dislocation creep conditions have frequently yielded values of n ‡ 50 pct. [12][13][14][15][16] On the other hand, measurements in fine-grained materials with d < 20 lm under dislocation creep conditions have led to n < 50 pct, [18] whereas the contribution is >50 pct under superplastic conditions.…”

Section: Introductionmentioning

confidence: 99%

Grain Boundary Sliding during Diffusion and Dislocation Creep in a Mg-0.7 Pct Al Alloy

Kottada

Chokshi

2007

Metall Mater Trans A

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Early studies on grain boundary sliding (GBS) in Mg alloys have suggested frequently that the contribution of GBS to creep is high even under conditions corresponding to dislocation creep. The role of creep strain and grain size in influencing the experimental measurements has not been clearly identified. Grain boundary sliding measurements were conducted in detail over experimental conditions corresponding to diffusion creep as well as dislocation creep in a singlephase Mg-0.7 wt pct Al alloy. The results indicated clearly that the GBS contribution to creep was very high during diffusion creep at low stresses (~75 pct) and substantially reduced during dislocation creep at high stresses (~15 pct). These measurements were consistent with the observation of significant intragranular slip band activity observed in most grains at high stresses and very little slip band activity at low stresses. The experimental measurements and analysis indicated also that the GBS contribution to creep was high during the initial stages of creep and decreased to a steady-state value at large strains.

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Superplasticity and grain boundary sliding characteristics in two stage deformation of Mg–3Al–1Zn alloy sheet

Cited by 110 publications

References 20 publications

Hot Deformation Mechanisms in AZ31 Magnesium Alloy Extruded at Different Temperatures: Impact of Texture

Hot Deformation Mechanisms in AZ31 Magnesium Alloy Extruded at Different Temperatures: Impact of Texture

Formability of Ultrafine-Grain Mg Alloy AZ31B at Warm Temperatures

Grain Boundary Sliding during Diffusion and Dislocation Creep in a Mg-0.7 Pct Al Alloy

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