复合挤压对Mg-4Sn-2Al-1Zn合金组织及力学性能的影响

Effect of Compound Extrusion on Microstructure and Mechanical Properties of Mg-4Sn-2Al-1Zn Alloy

针对镁合金室温强度低、塑性差的问题,采用复合挤压工艺在250℃对Mg-4Sn-2Al-1Zn合金进行了挤压,研究了复合挤压对合金的组织演变、织构及力学性能的影响。结果表明,复合挤压能将Mg-4Sn-2Al-1Zn合金的晶粒尺寸由45.2μm细化至3.1μm,组织均匀。挤压后的合金硬度提升,均匀性改善,屈服强度、抗拉强度和断后伸长率分别为204 MPa、287 MPa和21.0%,较匀质态分别提高了140.0%、91.3%和156.1%。动态再结晶是晶粒细化的主要机制,晶粒细化以及挤压后基面织构增强、织构向挤压方向均匀扩展使合金强度、塑性提高,挤压过程中Mg2Sn相破碎进一步提高了合金的力学性能。上述研究表明复合挤压是一种能有效提高镁合金综合性能的工艺。

Due to low strength and poor plasticity of magnesium alloys at room temperature,Mg-4Sn-2Al-1Zn alloys were extruded at 250℃by compound extrusion process,and the microstructure evolution,texture and mechanical properties of the alloys after extrusion were studied.The results show that the grain size of Mg-4Sn-2Al-1Zn alloy can be refined from 45.2mm to 3.1mm by one-step compound extrusion,and the structure is uniform.The hardness and uniformity of the extruded alloy increase,and the yield strength,tensile strength and elongation after fracture are 204 MPa,287 MPa and 21.0%,which are 140.0%,91.3%and 156.1%higher than those of the homogeneous state,respectively.Dynamic recrystallization is the main mechanism of grain refinement.Grain refinement and basal plane texture enhancement after extrusion,and the uniform texture expansion in the extrusion direction improve the strength and plasticity of the alloy,and the Mg2Sn phase breakage further improves the mechanical properties of the alloy during extrusion.The above studies show that compound extrusion can effectively improve the comprehensive properties of magnesium alloys.