Constrained groove pressing (CGP) is a novel severe plastic deformation (SPD) method suitable for fabricating ultra-fine grained (UFG) sheet metals. In this work, two passes of CGP were conducted to AZ31 magnesium alloy sheets at 523 K, and three routes including traditional CGP, 180° cross-CGP and 90° cross-CGP were employed to investigate the effects of pressing number and strain path on microstructure, texture and mechanical properties of the alloy sheets. The results show that, irrespective of CGP routes, a bimodal microstructure is developed in the deformed materials and the capability of CGP in fabricating UFG magnesium alloy sheets is confirmed by TEM observation. The superior grain refinement and microstructure homogenization is achieved in traditional CGP route from the as-annealed 9.85 μm–5.04 μm after one pass while no further improvement is observed after two passes. The average grain sizes are 5.69 μm and 5.18 μm after two passes of 180° cross-CGP and 90° cross-CGP, respectively. The average misorientation angle is mainly determined by the fraction of very high angle grain boundaries and texture and microstructure mechanisms dominate the generation of high angle grain boundaries in traditional and cross-CGP routes, respectively. The coexistence of strain free recrystallized grains and substructured/deformed grains is observed after one pass of traditional CGP due to incomplete dynamic recovery and dynamic recrystallization and promotes the subsequent activation of strain induced grain boundary migration, which may be postponed by employing cross-CGP routes. A double-peak basal texture with the basal poles inclined from ND to RD is developed in traditional CGP route while an inclination of the basal poles from ND to TD accompanied by a redistribution of the prismatic intensity toward RD is observed in cross-CGP routes due to the change of shear deformation direction. The texture softening plays a more important role in decreased strength than grain refinement in traditional CGP route while both grain refinement and texture modification contribute to the improvement of tensile properties in cross-CGP routes. Due to the inherent nature of CGP, the reverse loading condition between successive pressings cannot be changed even in cross-CGP routes. The relatively high processing efficiency in 90° cross-CGP route should be attributed to the unique strain accumulation sequence.

约束凹槽压制（CGP）是一种适用于制造超细晶粒（UFG）钣金的新型严重塑性变形（SPD）方法。在这项工作中，在523 K下对AZ31镁合金薄板进行了两次CGP加工，并采用了传统CGP，180°交叉CGP和90°交叉CGP三种路径来研究挤压次数和应变路径对合金薄板的显微组织，织构和力学性能。结果表明，与CGP路径无关，在变形材料中形成了双峰微观结构，并且通过TEM观察证实了CGP制备UFG镁合金薄板的能力。在传统的CGP工艺中，从退火后的9.85 μm–5可以实现卓越的晶粒细化和微观结构均质化。一次通过后为04μm，而两次通过后未观察到进一步的改善。经过两次180°交叉CGP和90°交叉CGP的平均晶粒尺寸分别为5.69μm和5.18μm。平均取向差角主要由非常高角度的晶界的比例决定，在传统和交叉CGP路线中，质地和微观结构机制分别主导着高角度晶界的产生。由于不完全动态恢复和动态再结晶，传统CGP经过一遍后，观察到无应变的再结晶晶粒与亚结构/变形晶粒共存，并促进了应变诱发的晶界迁移的后续活化，这可能通过采用跨CGP的路线而推迟。在传统的CGP路线中形成了一个基极从ND向RD倾斜的双峰基质，而在CGP交叉路线中，观察到了从ND到TD的基极倾斜以及棱柱强度向RD的重新分布。改变剪切变形方向。与传统的CGP路线中的晶粒细化相比，纹理软化在强度降低中起着更重要的作用，而晶粒细化和纹理修饰都有助于跨CGP路线中的拉伸性能的改善。由于CGP的固有特性，即使在跨CGP路线中，连续压制之间的反向加载条件也无法更改。90°CGP交叉路径中相对较高的处理效率应归因于独特的应变积累序列。