An industrial plastic deformation method involving large strain induction, known as ring rolling (RR), was applied after initial upsetting to produce an ultra-fine-grained Mg ring part with superior hydrogen storage capabilities at industrial scale. The microstructure evolution and hydrogen storage characteristics of the Mg–3Zn–1Ca-0.5Mn alloy (ZX31) were analyzed to establish a correlation between grain structure and hydrogen storage behavior. The enhanced hydrogen storage performance of the ring-rolled material was compared to the upset-only condition using Sievert testing. Results revealed that hydrogen absorption and desorption kinetics are governed by the level of plastic strain and the associated microstructure/substructure modifications induced during processing. Grain refinement achieved through hybrid hot upsetting-ring rolling promoted the formation of effective interfaces, leading to improved hydrogen uptake kinetics. Transmission electron microscopy (TEM) of the severely deformed samples showed the development of dislocation substructures, highlighting their critical role in controlling hydrogen storage performance. Finally, the relationship between hydrogen storage and release kinetics and the microstructure-substructure features was discussed.

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