This paper describes the main results from an experimental investigation into the consequence of cyclic bending under tension on elongation-to-fracture (ETF) and strength of AZ31 sheets. The deformation is imparted on test specimens of the alloy using a recently built continuous-bending-under-tension (CBT) apparatus conceived to increase ETF relative to simple tension (ST). The apparatus pulls the specimen in tension with a certain velocity while the specimen reciprocates through a set of three rollers, which impart a given amount of bending. The parameter space consisting of bending depth, crosshead velocity, and sheet thickness is explored to achieve the greatest ETF for the alloy. However, only moderate improvements in ETF are obtained. The small improvements are attributed to the relatively uniform elongation of the alloy during both CBT and ST with a small amount of the remaining ductility to deplete throughout the sheet by CBT after exhausting the uniform elongation. Measurements of the grain structure and texture evolution using electron-backscattered diffraction and neutron diffraction reveal slip dominated deformation with some twinning followed by de-twinning. The behavior of the alloy upon CBT processing to a certain number of CBT cycles followed by heat treatments (HT) is also investigated to achieve tradeoffs in strength and ductility. Results and insights from these investigations are presented and discussed. Significantly, it is shown that the strength of the alloy can be increased for over 30% while preserving at least 5% of its ductility.

本文介绍了对拉伸下循环弯曲对 AZ31 板材的断裂伸长率 (ETF) 和强度的影响的实验研究的主要结果。使用最近建造的连续弯曲-张力 (CBT) 设备对合金的试样施加变形，该设备旨在增加相对于简单张力 (ST) 的 ETF。该装置以一定的速度拉动试样，同时试样通过一组三个辊子往复运动，这些辊子赋予给定的弯曲量。探索了由弯曲深度、十字头速度和板材厚度组成的参数空间，以实现合金的最大 ETF。然而，ETF 只获得了适度的改进。小的改进归因于在 CBT 和 ST 期间合金的相对均匀的伸长率，在均匀伸长率耗尽后，少量剩余的延展性通过 CBT 耗尽整个板材。使用电子背散射衍射和中子衍射对晶粒结构和织构演化的测量揭示了滑动主导的变形，其中一些孪晶随后去孪晶。还研究了合金在 CBT 加工到一定数量的 CBT 循环后进行热处理 (HT) 后的行为，以实现强度和延展性的权衡。对这些调查的结果和见解进行了介绍和讨论。值得注意的是，表明合金的强度可以提高 30% 以上，同时保持至少 5% 的延展性。