基于摩擦挤压增材制造的单道多层6061铝合金组织特征与力学性能

Microstructure Features and Mechanical Properties of Single-Pass Multilayer 6061 Aluminium Alloy Based on Friction Extrusion Additive Manufacturing

成功实现了6061铝合金摩擦挤压增材制造(friction extrusion additive manufacturing,FEAM)工艺,对单道1层、2层及9层增材试样组织特征、界面连接机制及力学性能进行了分析讨论。结果表明:在主轴转速600r/min和移动速度300mm/min下可获得完全致密无内部缺陷的每层厚度和宽度分别约为4和32mm的6061单道1层、2层及9层增材试样。增材组织均匀完全由细小等轴晶组成,单道1层和单道9层平均晶粒尺寸分别为5.63±1.66μm和8.31±1.67μm,与填充棒料母材(24.21±5.3μm)比较晶粒明显细化。单道1层增材组织内部强化相β″几乎全部溶解而β′发生粗化,平均硬度为母材的64.7%。增材界面实现冶金连接且晶粒细化最显著,由于强化相β″及β′几乎全部溶解,其硬度降低为母材的56.9%,单道9层试样因多次热循环降低为母材的50.6%。单道9层增材试样具有优良的强韧匹配,沿增材层长度方向平均抗拉强度和断后伸长率分别为194.25MPa和34.6%,沿增材层垂直方向(Z方向)平均抗拉伸强度和断后伸长率分别为151.0 MPa和10.4%。

The friction extrusion additive manufacturing(FEAM) process of 6061 aluminium alloy was successfully performed. The microstructure features, interface bonding mechanism and mechanical properties of single-pass one-layer, two-layer and nine-layer additive specimens were discussed in detail. It is found that under the process conditions of a spindle speed of 600 r/min and a moving speed of 300 mm/min, completely dense and defect-free 6061 one-layer, two-layer and nine-layer additive specimens with layer thickness and width of 4 and 32 mm are obtained. The uniform microstructures of additive specimens are composed of fine equiaxed grains. The average grain size of one-layer and nine-layer additive specimens are 5.63±1.66 μm and 8.31±1.67 μm, respectively, which are significantly refined compared with the bar base metal(24.21±5.3 μm). In the microstructures of single-pass one-layer additive specimen, the main strengthening phase β″ is almost completely dissolved and phase β′ is coarsed, so the average hardness is 64.7% of the bar base metal. The additive interface realizes metallurgical bonding and has the most significant degree of grain refinement. The hardness of interface reduce to 56.9% of the bar base metal because the strengthening phases β″ and β′ are almost completely dissolved. The average hardness of nine-layer specimen after multiple thermal cycles is 50.6% of the base metal. The nine-layer additive specimen exhibits excellent strength and toughness matching. The average tensile strength and elongation along the length direction of the additive specimen are 194.25 MPa and 34.6%, respectively, and the average tensile strength and elongation along the vertical direction of the additive specimen are 151.0 MPa and 10.4%, respectively.