(南京理工大学 材料科学与工程学院，南京 210094)
摘 要: 针对高强铝镁合金增材构件性能难以提升的问题，探索研究了提高铝镁合金中的镁组分这一方法的可行性。基于钨极氩弧增材制造工艺，采用以ER5356为主要熔化丝材、以少量AZ31为辅助熔化丝材的双丝同步熔化方式，通过调整两种丝材的送丝速度比例，增材制造了5组高镁组分的铝镁合金直壁体，并对这5组直壁体的显微组织特征、演化规律和力学性能进行研究。结果表明：随着AZ31与ER5356送丝速度比从1:10提升到1:3，α(Al)相由等轴晶转变为枝晶，β-Al3Mg2相转变为晶间偏析型离异共晶；试样的平均晶粒尺寸由17.26 μm先增大到21.35 μm再减小到14.69 μm；β相和共晶组织的含量呈上升趋势。相较于单丝铝镁合金增材构件，高镁组分增材构件的平均显微维氏硬度达到114.93 HV，提升了64.2%；抗拉强度达到342 MPa，提升了24.8%。
关键字: 双丝增材制造；高强铝镁合金；显微组织；力学性能
（School of Material Science and Engineering, Nanjing University of Science &Technology, Nanjing 210094, China）
Abstract:As the properties of the high strength Al-Mg alloy component is difficult to be improved, a new gas tungsten arc additive manufacturing process was proposed to increase the Mg content in Al-Mg alloy component. Two heterogeneous wires were synchronously fed into the same molten pool, using ER5356 as the main melting wire, and a small amount of AZ31 as the auxiliary melting wire. Five groups of thin wall components with high Mg content were deposited by adjusting the ratio of the feed speed of the two wires. The microstructural characteristics, evolution and mechanical properties of the components were investigated. The results show that with the wire feed speed ratio between AZ31 and ER5356 increasing from 1:10 to 1:3, the α(Al) phase transforms from equiaxed grains to dendrites, and the β-Al3Mg2 phase transforms into divorced eutectics. The average grain size increases from 17.26 μm to 21.35 μm and then decreases to 14.69 μm, meanwhile, the content of the β phase and the eutectic structure increases. Compared with the Al-Mg alloy component deposited by traditional single wire feed gas tungsten arc additive manufacturing process, the micro Vickers hardness of the high Mg content components reaches 114.93 HV on an average, increased by 64.2% and the ultimate tensile strength reaches 342 MPa, increased by 24.8%.
Key words: double wires additive manufacturing; high strength Al-Mg alloy; microstructure; mechanical properties
