Strain rate-induced crystallographic texture development in tensile deformation of a rapidly solidified thin-strip cast AA5182 Al-Mg alloy

Abstract

This study investigates the evolution of ultimate crystallographic texture in AA5182 Al-Mg alloy under uniaxial tensile deformation at quasi-static strain rates (10 −3 and 10 −1 s −1 ), focusing on two casting routes of thin-strip (TS) and direct-chill (DC) casting. The TS sample, solidified at ∼10 3 K/s, exhibited an initial average grain size of 49.7 μm, significantly finer than the 114.5 μm observed in the DC counterpart solidified at a cooling rate of ∼10 1 –10 2 K/s. The fraction of intermetallic particles in the TS sample (∼2.74 %) was markedly lower than in the DC sample (∼6.07 %), contributing to enhanced solute supersaturation and reduced strain localization, which is linked to a lower frequency of low-angle misorientations within the matrix. Texture analysis revealed that TS samples experienced an approximately 28 % increase in texture index (from 1.32 to 1.69) with increasing strain rate, compared to a 15 % rise in DC samples (from 1.75 to 2.01), indicating more pronounced strain-induced texture development in the TS sample. Taylor factor (M) analysis showed a greater fraction of favorably oriented grains (M ≤ 2.5) in as-cast TS samples, increasing from 11.5 % to 14.0 % after deformation, compared to an increase from 7.5 % to 14.6 % in the DC samples. However, the DC sample exhibited greater strain localization and a higher kernel average misorientation (KAM, 0.83 vs. 0.67), consistent with its higher density of intergranular/interdendritic intermetallic particles and coarser structure. It was demonstrated that in the TS sample, strain accommodation primarily occurred through grain rotation and dislocation annihilation, facilitated by lower particle density and higher solute supersaturation. By contrast, the DC sample accommodated strain mainly through dislocation pile-ups and boundary-mediated mechanisms, resulting in more constrained deformation behavior. The unique microstructure in the TS sample enabled a broader range of grain rotation trajectories, resulting in a higher number of distinct texture evolution pathways. These findings underscore the critical role of casting routes in governing texture development and highlight the superior potential of the TS sample for enhanced ductility and formability under dynamic loading conditions.

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