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提出了等通道螺旋转角挤压(equal channel helix angular extrusion,ECHE)变形方法,采用Deform-3D平台的有限元模拟、OM、SEM、TEM、拉伸试验等方法,研究了ECHE制造AZ31镁合金轻质螺栓坯料的挤压工艺、温度场、合金流动情况、组织和性能。结果表明:在变形温度为380℃,挤压速度为3mm·s-1时,合金变形均匀,不易出现挤压缺陷;等通道螺旋转角挤压变形可以显著细化AZ31镁合金晶粒;其挤压过程中晶粒细化机制为晶粒破碎和动态再结晶;挤压后的平均晶粒尺寸为3～5μm,且合金晶粒大小均匀;力学性能较铸态大幅度提高,室温抗拉强度和屈服强度分别由209和104MPa提高到286和165MPa,延伸率由11%提高到26.4%,拉伸断口呈现为韧窝断裂和准解理断裂的混合特征。
In this paper, the equivalent channel helix angular extrusion (ECHE) deformation method is proposed. By using Deform-3D platform finite element simulation, OM, SEM, TEM, tensile test and other methods, ECHE manufacturing AZ31 magnesium alloy light Extrusion process of mass bolt blanks, temperature field, alloy flow, microstructure and properties. The results show that when the deformation temperature is 380 ℃ and the extrusion speed is 3mm · s-1, the deformation of the alloy is uniform and the extrusion defects are not easy to occur. The extrusion deformation of the channel spiral can remarkably refine the grains of AZ31 magnesium alloy. The grain refinement mechanism during the pressing process is grain breakage and dynamic recrystallization. The average grain size after extrusion is 3 to 5 μm, and the grain size of the alloy is uniform. The mechanical properties are greatly improved compared with the as-cast state, and the room temperature tensile strength And yield strength increased from 209 and 104 MPa to 286 and 165 MPa, respectively, while the elongation increased from 11% to 26.4%. The tensile fracture showed mixed features of dimple fracture and quasi-cleavage fracture.