This paper explored how the work hardening process enhances the yield strength (YS) of magnesium alloy and established a novel quantitative relationship between microstructure and YS. The YS of an extruded Mg–Nd–Zn–Zr alloy was nearly tripled by rotary swaging at 200 ℃, attributing to dislocation accumulation, grain fragmentation, and basal texture formation. A modified Hall–Petch relationship (GM–HP) was established by introducing the equivalent orientation factor and dislocation density to accurately quantify the YS and the contribution of each strengthening mechanism. The contributions of dislocation hardening and grain boundary strengthening were multiplied by the strong basal texture. This paper offered valuable insights and guidance for designing and optimizing high-strength wrought magnesium alloys and their plastic processing methods.

Multi-direction impact forging (MDIF) was applied to the as-extruded ZK60 Mg alloy, and the microstructure, texture evolution and yield strength symmetry were investigated in the current study. The results showed that the average grain size of forged piece was greatly refined to 5.3 µm after 120 forging passes, which was ascribed to the segmenting effect of {10–12} twins and the subsequent multiple rounds of dynamic recrystallization (DRX). A great deal of {10–12} twins were activated at the beginning of MDIF process, which played an important role in grain refinement. With forging proceeding, continuous and discontinuous DRX were successively activated, resulting in the fully DRXed microstructure. Meanwhile, the forged piece exhibited a unique four-peak texture, and the initial <10−10>//ED fiber texture component gradually evolved into multiple texture components composed of <0001>//FFD (first forging direction) and <11–20>//FFD texture. The special strain path was the key to the formation of the unique four-peak texture. The {10–12} twinning and basal slip were two dominant factors to the evolution of texture during MDIF process. Grain strengthening and dislocation strengthening were two main strengthening mechanisms of the forged piece. Besides, the symmetry of yield strength was greatly improved by MDIF process.