The effects of rolling temperature at 300

330

360 ℃ and rolling strain at three passes on the microstructure and hardness of the AZ31 magnesium alloy sheets have been investigated. The results showed that the rolling can obviously refine the grain size in the magnesium sheets and improve its hardness. The grain size in the AZ31 magnesium alloy sheets would be coarsened with raising the rolling temperature at the same strain

which results in the decrease of hardness of the alloy sheets. However

the alloy sheets exhibit better comprehensive properties with rolling at 330 ℃. The grain size of the alloy sheets is decreased and the hardness is gradually increased with increasing strain and rolling passes at 330 ℃. After three passes with 40% strain per pass

the magnesium alloy sheets with uniformly distributed structure and fine grain size as well as crack-free inside or on the surface could be obtained

where the average grain size of the sheets are decreased from 120 μm to 3

4

μm

and the hardness （HRA） is increased from 23.8 to 36.5.