Microstructures And Mechanical Properties Of AM60 Magnesium Alloy Sheet Processed By Equal Channel Angular Rolling

Increase usage of magnesium components in the industries has propelled considerable research interest on the development of magnesium alloy,especially deformation magnesium alloy with excellent composite properties. However,the secondary deformation abilities are badly restricted by the (0002) basal texture of magnesium alloy sheets with normal rolling. Therefore,Mg-6%Al-0.5%Zn-0.5%Mn (AM60) alloy was subjected to Equal Channel Angular Rolling(ECAR)processing with 105omodul at 400℃. Microstructure observations and mechanical properties were carried out using optical microscope and tensile was tested. Annealing treatments were carried out with different periods. The study shows that(1) Twins refinement are observed in AM60 magnesium alloy with ECAR and the grain size decreases. The grain size is 10μm and 5μm before and after ECAR. The grain shapes of ECAR AM60 magnesium alloy sheet are not regular. Typical severe plastic deformation microstructure appeares.(2) It is found that the"c"axis orientation of the sheet processed by ECAR is changed and the crystal orientation evolves from (0002) basal plane orientation to non-basal plane. Non-basal texture of grains appeares. The existence of non-basal texture is advantageous to secondary deformation.(3) The rheological behavior is affected by refined grains and non-basal texture. The rheological behavior after ECAR changes obviously especially along rolling direction. The grain boundary deformation ability gets enhanced after ECAR,strength and plasticity of ECAR AM60 sheets get enhanced too,the ultimate tensile strength increases from 222 to 372 MPa and the yield strength increases from 156 to 260 MPa along rolling direction,the ultimate tensile strength increases from 268 to 380 MPa and the yield strength increases from 188 to 265 MPa along transverse direction.(4) Symmetrical axis grains and shape grains appeare after annealing treatment. Grains begin to grow up,twins begins to disappear with the annealing time going on. After 60 minutes annealing treatments,the grain boundary with 120o appears and shape grains begin to be symmetrical axis grains.(5) Sheet strength decreases after annealing treatments,because grains grew up and twins refinement began to disappear. The decreased density of the locations makes the strength low too. Twins decreases but symmetrical axis grains appeares after annealing treatment. So,strength decreases,plasticity get enhanced more. The amounts of the twins decrease obviously but the non-basal orientation of the grains processed by ECAR changes little. The effect of annealing treatments with 30 minutes at 300℃is observed better in our results.