Improvements in elongation and tradeoffs in strength and ductility of several Mg sheet alloys through cyclic bending under tension and annealing
Improvements in elongation and tradeoffs in strength and ductility of several Mg sheet alloys through cyclic bending under tension and annealing
复制标题
DOI：
10.1007/s12289-023-01776-x
复制
发表时间：
2023-09-01
影响因子：
2.4
通讯作者：
Knezevic，Marko
中科院分区：
文献类型：
--
作者：
Matukhno，Nikolai;Kljestan，Nemanja;Knezevic，Marko
本文介绍了从实验研究中获得的结果，以确定循环弯曲下拉伸（CBT）和退火的影响，断裂伸长率（ETF）和权衡强度和塑性的三种镁合金板：ZEK100，BioMg250，Mg4Li。CBT工艺通过使片材试样经受与十字头运动同时的张力和与一组沿试样沿着往复运动的辊一起的弯曲，来递增地赋予比在简单张力（ST）中可实现的更大的均匀变形。初步探索了ZEK100合金实现最大弯曲变形量的工艺参数空间，包括十字头速度和弯曲深度。使用CBT相对于ST获得约40%的ETF的改进。给定由CBT赋予的大塑性应变的均匀变形，接下来通过使合金板在优化的参数和随后的退火下经受一定数量的CBT循环来研究合金的强度和延展性的折衷。发现合金的强度沿着板最强方向（轧制方向）增加1.4倍，沿着板最软方向（横向）增加2倍。由于强度沿着软方向比沿着硬方向提高得更多，合金的各向异性减小。值得注意的是，强度可以沿软方向增加约沿着40%，同时降低各向异性并在每个方向上保持至少10%的合金延展性。利用电子背散射衍射和织构演化的微观结构演变的表征，采用中子衍射揭示滑移为主的变形的合金。BioMg250和Mg4Li板材合金的类似处理和测试在提高伸长率和改善对比强度和延展性方面产生了更好的结果。全面的数据为三种合金和见解的调查和讨论。
This paper presents results acquired from experimental investigations into determining the influence of cyclic-bending-under-tension (CBT) and annealing on elongation-to-fracture (ETF) and tradeoffs in strength and ductility of three Mg sheet alloys: ZEK100, BioMg250, and Mg4Li. The CBT process imparts uniform deformation greater than achievable in simple tension (ST) incrementally by subjecting a sheet specimen to simultaneous tension with a crosshead motion and bending with a set of rollers reciprocating along the specimen. The space of process parameters including crosshead velocity and bending depth is explored initially to achieve the greatest ETF of ZEK100 alloy. Improvements in ETF of about 40% are attained using CBT relative to ST. Given the uniform deformation imparted by CBT to large plastic strains, tradeoffs in strength and ductility of the alloy are investigated next by subjecting the alloy sheets to a certain number of CBT cycles under the optimized parameters and subsequent annealing. Strength of the alloy is found to increase by a factor of 1.4 along the sheet strongest direction, the rolling direction, and a factor of 2 along the sheet softest direction, the transverse direction. Since the strength improved more along the soft direction than along the hard direction, the alloy anisotropy reduces. Significantly, the strength can increase for about 40% along the soft direction, while reducing the anisotropy and preserving at least 10% of the alloy ductility in every direction. Characterization of microstructural evolution using electron-backscattered diffraction and texture evolution using neutron diffraction revealed slip dominated deformation of the alloy. Similar processing and testing of BioMg250 and Mg4Li sheet alloys produced even better results in terms of enhancing elongation and improving the contrasting strength and ductility properties. Comprehensive data for the three alloys and insights from the investigations are presented and discussed.