| Friction stir processing(FSP) is a new fine grained material fabricated technology. Grain size, texture and second phase have a significant effect on mechanical behavior of magnesium alloys. In this paper, AZ80 magnesium alloy, which can be heat treated strengthening, was studied. Fine-grain magnesium alloys with different grain sizes and orientations were prepared by FSP technology, the microstructure and texture characters of the stir zone(SZ) were analyzed, and the effects of grain size, texture and second phase on the mechanical properties of fine-grain magnesium alloys were discussed. The main conclusions of the paper are as follows:When the rotating speed is from 400 r/min to 1600 r/min and traveling speed is from 50 mm/min to 400 mm/min, good processing surface can be obtained, the rotating speed has a greater influence on the microstructure; AZ80 magnesium alloy sheet was subjected to friction stir processing to generate average grain sizes ranging from 1.65 μm to 9.22 μm, as the grain size refinement, Zener-Holloman parameters, hardness and yield strength increase, the initial work-hardening rate decreases; The stirring zone(SZ) exhibited a strong basal texture(0002), c-axis of base texture along Normal Direction(ND) to Processing Direction(PD) 30°~40° deflection, the tensile properties along transverse direction(TD) and PD were significantly anisotropic at room temperature; the tensile deformation mechanisms were dominated by prismatic slip and basal slip along TD and PD, respectively, the third stage of softening rate along TD is 4~6 times along PD.The law of effect of aging temperature on hardness: the time of peak aging at 240℃ is shorter, the second is 180℃, and the longest is 120℃; When 180 ℃ ageing, the second phase volume fraction, yield strength and hardness were all stable after the first increase trend with the extension of aging time, elongation rate decreased gradually with the aging time. |
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