采用单向拉伸实验研究温热条件下挤压态AZ31镁合金板材5个不同方向的力学性能、显微组织、断口形貌.结果表明:挤压态镁合金力学性能具有明显的各向异性,170℃时,各向异性最明显,随着拉伸方向与挤压方向所呈角度的增大,抗拉强度从217 MPa增大到271 MPa,屈服强度却从174 MPa减小到71 MPa.镁合金在温热条件下变形机制为{10-12}拉伸孪生、{10-11}压缩孪生和{0001}基面(a)滑移;沿着不同角度拉伸时,变形机制有所不同.拉伸方向与挤压方向的角度小于45°时,挤压态镁合金表现为微孔聚集型的韧性断裂;且随着角度的增大,表现为韧-脆混合断裂,其中角度为67.5°时,镁合金以解理方式断裂.
The tensile properties,microstructure,appearance of fracture in five different planar directions of extruded AZ31 magnesium alloy sheets at the warm-temperature were investigated by uniaxial compression test.The results indicate that the extruded magnesium alloy sheets show high anisotropy,and the most obvious anisotropic temperature is 170 ℃.With the increase of the angle between tensile direction and extrusion direction,the tensile strength increases from 217 MPa to 271 MPa,and the yield strength decreases from 174 MPa to 71 MPa.There are three deformation mechanisms of magnesium alloys at warm-temperature,which include {10-12} extension twinning,{10-11} compression twinning and base slip.The deformation mechanism is different at different stretching angles.When the angle between tensile direction and extrusion direction is less than 45°,the fracture mechanism of magnesium alloy is micropore aggregation fracture.With the increase of angle,it is the mixed fracture of toughness and brittleness,and the cleavage fracture occurs at the angle of 67.5°.
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