| Magnesium alloy have the advantage of lightweight but the limited ability in plastic forming. The cost of sheet rolling keeps high due to the huge investment in equipment for blooming roller and the multi-rolling and annealing in the forming of sheet. Only the domestic defense industry and aerospace area can afford the cost of high-performance sheet, which is still depend on import. Since the method of extrusion blooming before rolling is a efffective way to deform the metal with poor formability, it is very important to carry on a deep research on this method. In this paper, the processes of extrusion- longitudinal rolling and extrusion- transverse rolling were investigated with the alloy of ZM21 and other two alloys with lwo and high content of Ce. With experiments of the commercial extrusion and rolling, mechanical properties test at room temperature, microstructure analysis, and the scanning electron microscopy observation for fracture morphology, the possibility of blooming extrusion followed by rolling for magnesium alloy is proved. The effects of alloy content, rolling direction and rolling reduction on the mircostructure and mechannical propertise and their anisotropy were investigated. Test results show that:A refine uniform structure of recrystallization can be obtained by extrusion blooming at the temperature of 420℃, with a extrusion ratio of 175 and a homogenization treatment of 420℃×12h. With the increase of Ce content, the grain becomes smaller in size. The grain size of ME0 (the Ce-free alloy (ZM21) )is about 21μm, and for Low Ce (0.19%) alloy ME3 the size is about 18um, for high-Ce (0.57%) alloy ME7 is about 13um; Tensile strength: the strength of ME0 in 0°and 90°direction are close to each orther, between 245MPa and 250MPa, 10MPa higher than 45°direction. The strength increases more than 10MPa in all directions and decalines in relative differences for the alloy with Ce addition, with the except that the ME7 only has little increasing in 0°direction. Yield strength: except that the strength of ME3 in 0°direction and that of 90°in ME7 are close 150MPa, other strength of the alloys in different directions are all between 135-140MPa. Elongation: ME0 in 0°and 90°direction are about 10%, 45°direction for the 22%..With the addition of Ce, the elongation of all directions has a improvement of 5-10% while the 90°direction of ME7 dropped to 12%. Comparing the IPA indexes of different alloys shows, ME3 is the best for a good combination of strength and elongation IPA, with the IPA of tensile strength is 1.82%, the IPA of yield strength is 8.1%, and the IPA of elongation is 23%. Among the three alloy with different Ce content, the ME7 has relative high IPA. The ME0 and ME3 alloy have a better exhibition of be identical in all directions.The fibrous structure from extrusion is maintained in the ME0 alloys after transverse rolling or longitudinal rolling at reduction of 31.0%, while the structure become equiaxed in view of both sideway and endways at reduction of 44.8%. Grain size after rolling are mainly in the 10-20um. The strength of ME0 alloy improves with the increase of deformation, sepecialy for the yield strength. By longitudinal rolling, the tensile strength and yield strength of the direction of 90°are the highest and that of 0°direction is the lowest, with a difference of about 40MPa. The elongation increases firstly and then decreases with the increase of deformation, while that of 45°direction is always about 5% higher than the other two directions. By transverse rolling, the strength in the 90°direction is slightly higher than others with about 40MPa at small amount of deformation. When the deformation to 44.8%, the tensile strength is about 280MPa, and the yield strength is around 220MPa, with the difference of that in different directions is not more than 10MPa. The elongation of 90°direction is as higher as bouble of the direction of 0°in the low deformation, while the elongations in all directions are basically equivalent when the deformation achieve to 45%. The transverse rolling is better than the longitudinal rolling to keep the isotropy of mechanical propertiseAfter longitudinal rolling and transverse rolling, ME3 alloy need to a deformation of over 44.8% so that to get fully equiaxed structure, with very fine grains of size mainly about 5μm. The strength increases firstly with the longitudinal rolling and transverse rolling deformation increasing, and then when the deformation is over 44.8% decreases. The elongation for longitudinal rolling has a strong consistency, and the elongation of the three directions is all in 17% to 18% when the deformation is 65.5%. The elongation of transverse rolling in 45°direction is always the highest and increases slowly from 12% to 16% with the increasing of deformation, while that of 90°direction is the lowest when the deformation is smaller than 44.8% and it will keep up with that of the 45°direction when the deformation is 65.5%. The longitudinal rolling is better than the transverse rolling to keep the isotropy of mechanical propertise of ME3.With the deformation increasing of longitudinal rolling to ME7 alloy, the tensile strength changes in the scope of 270-310MPa, the yield strength improves obviously from 180 MPa to 230MPa when the deformation changes from 44.8% to 65.5%, the elongation weakens seriously especially for the 0°direction. After transverse rolling, the average strength of all direction is 70MPa higher than that of as extruded, and the strength increases littile as the dieformation increases. The elongaton of the rolled sheet decreases heavily, almost as half as that of as extruded salb in the 90°direction。Comparison with transverse rolling and longitudinal rolling, it can be found that transverse rolling is good for getting more uniform micro-structure of 90°and 0°direction, especially when the transverse rolling deformation is low, that is helpful to control the anisotropy. In contrast, the large deformation for longitudinal rolling is good for make all mechanical propertise coincident in different directions.By Comparing of IPA for rolled sheet of three alloys; we can find that the anisotropy of ME7 plates was significantly serious than the other two alloys, ME0 and ME3, their sheet are not so different in IPA. ME0 alloy is suitable to transverse rolled. When the reduction achieved in more than 44.8% the mechanical properties in different directions get a strong consistency, while the tensile strength of the three directions is all between 258Mpa and 295MPa, and the yield strength is in 173Mpa-203Mpa, and the elongation is in 11.2% -22%. ME3 alloy is suitable to longitudinal rolled, with the reduction increasing the consistency of elongation significantly improved and strength consistency is good too. When the reduction is 66.5%, tensile strength is between 244MPa and 267MPa, yield strength is between 135MPa and 138MPa, elongation is between 17.3% and 18.1%.
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