DIC를 활용한 선압축과 후열처리 공정을 거친 AZ31 마그네슘 압연재의인장 변형 거동 분석

This study investigates the effects of precompression and subsequent annealing on the tensile deformation behavior of a rolled AZ31 Mg alloy at room temperature using digital image correlation (DIC). When the as-rolled sample (AR sample) is subjected to precompresssion along the rolling direction (RD) and transverse direction (TD), the sample's texture changes from the typical normal direction (ND)-oriented basal texture to the RD- and TD-oriented basal textures, respectively, because of the lattice reorientation by {10-12} twinning. During tension along the RD, the AR sample and the sample precompressed along the TD and subsequently annealed at 250 ^oC (TDCA sample) accomodate the tensile strain via dislocation slip, resulting in high yield strengths and slip-dominant strain-hardening behaviors. In contrast, the sample precompressed along the RD and subsequently annealed at 250 ^oC (RDCA sample) exhibits a low yield strength and twinning-dominant strain-hardening behavior, owing to the vigorous activation of {10-12} twinning during tension. DIC results reveal that in the AR sample, noticeable strain localization occurs at an early stage of tensile deformation due to the difficulty of accommodating strain along the thickness direction. In the RDCA sample, strain distribution is relatively homogeneous via {10-12} twinning, but the rapid strain hardening caused by abundant {10-12} twins causes premature crack initiation. Because the basal planes of most grains of the TDCA sample are aligned parallel to the thickness direction, the thickness strain is effectively accommodated via prismatic slip, resulting in the highest tensile elongation among the three samples.