Effect of dislocation transmutation on modeling hardening mechanisms by twinning in magnesium

Oppedal, A.L.; Kadiri, Haitham El; Tomé, Carlos N.; Kaschner, G.C.; Vogel, Sven C.; Baird, James C.; Horstemeyer, M.F.

doi:10.1016/j.ijplas.2011.09.002

Cited by 194 publications

(83 citation statements)

References 31 publications

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“…The quilted structure forms through the blocking and propagation of the above-mentioned active twinning systems. These features have been widely observed within orthotropic materials [21][22][23][24][25][26][27][28][29]. Twin broadening was observed from the top surface to a depth of * 400 lm.…”

Section: Resultsmentioning

confidence: 53%

Response of Ti microstructure in mechanical and laser forming processes

et al. 2018

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Microstructural deformation mechanisms present during three different forming processes in commercially pure Ti were analysed. Room temperature mechanical forming, laser beam forming and a combination of these two processes were applied to thick metal plates in order to achieve the same final shape. An electron backscatter diffraction technique was used to study the plate microstructure before and after applying the forming processes. Substantial differences among the main deformation mechanisms were clearly detected. In pure mechanical forming at room temperature, mechanical twinning predominates in both compression and tensile areas. A dislocation slip mechanism inside the compression and tensile area is characteristic of the pure laser forming process. Forming processes which subsequently combine the laser and mechanical approaches result in a combination of twinning and dislocation mechanisms. The Schmid factor at an individual grain level, the local temperature and the strain rate are factors that determine which deformation mechanism will prevail at the microscopic level. The final microstructures obtained after the different forming processes were applied are discussed from the point of view of their influence on the performance of the resulting formed product. The observations suggest that phase transformation in Ti is an additional microstructural factor that has to be considered during laser forming.

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Section: Resultsmentioning

confidence: 53%

Response of Ti microstructure in mechanical and laser forming processes

et al. 2018

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“…[25] Although models are now available for these other hardening effects, [25,26] it is not obvious how these can be adapted to include the effect of precipitates. In this study, a simpler, semi-quantitative approach is taken by modifying the effective CRSS for f10 " 12g twinning derived from model calibration in a precipitate-free case to consider the additional increment in CRSS that would be expected from precipitates.…”

Section: Origin and Elimination Of Asymmetrymentioning

confidence: 99%

Effect of Precipitate Shape and Habit on Mechanical Asymmetry in Magnesium Alloys

Robson

Stanford

Barnett

2012

Metall Mater Trans A

104

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Asymmetric yield behavior in tension and compression is a common and usually undesirable feature of wrought magnesium alloys. To prevent yield asymmetry, it is necessary to favor slip over twinning, as it is the unidirectional nature of twinning combined with the strong textures produced in wrought magnesium alloys that produce yield asymmetry. In this article, the potential to use precipitates to strengthen selectively against twin growth is discussed. The effect of precipitate's shape and habit on strengthening of slip and twinning is calculated using simple Orowan-based models. It is shown that basal plate precipitates, although being poor strengtheners against basal slip, are good strengtheners against twin growth. This is because they produce the maximum unrelaxed back-stress when they remain unsheared inside the twin. The predictions of the model have been validated against experiments for two alloys that form different precipitate types: AZ91 (basal plates). and Z5 (c-axis rods). Crystal plasticity modeling has been used to predict that an optimized distribution of basal plate precipitates is expected to strongly reduce yield asymmetry, even in strongly textured magnesium alloy.

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“…[3][4][5][6][7] Jiang et al [8] and Yang and Zhang [9] reported that different twin variants and twin-twin intersections are associated with the deformation stage with a higher strain hardening rate in AZ31 Mg alloy which is subjected to compression along the extrusion direction. Ma et al [10] and Oppedal et al [11] found that multivariants are activated to accommodate large straining and the subsequent twin-twin interaction contributes to a significant strain hardening. El Kadiri et al [12] compared twin growth behavior in two grains that contain different numbers of * Corresponding authors.…”

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confidence: 99%