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

摘要:

本文成功实现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。试验表明：在主轴转速600 rpm和移动速度300 mm/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 mm和32 mm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±1.66 μm和8.31±1.68 μm,与填充棒料母材比较晶粒(24.21±5.3 μm)明显细化。单道1层增材组织内部强化相b2几乎全部溶解而b′发生粗化,平均硬度为母材的64.7%。增材界面实现冶金连接其晶粒细化最显著,由于强化相b2及b′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 MPa和34.6%,沿增材层垂直方向平均拉伸强度和断后伸长率分别为151.0 MPa和10.4%。

关键词:固相增材制造;6061铝合金;微观组织;力学性能;析出相

Abstract:

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 rpm and a moving speed of 300 mm/min, completely dense and defect-free 6061one-layer, two-layer and nine-layer additive specimens with layer thickness and width of 4 mm and 32 mm are obtained. The uniform microstructures of additive specimens are composed of fine and uniform equiaxed grains. The average grain size of one-layer and nine-layer additive specimens are 5.63±1.66 μm and 8.31±1.68 μm, 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 b2 is almost completely dissolved and phase b′ 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 b2 and b′ 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 MPa and 34.6%, respectively, and the average tensile strength and elongation along the vertical direction of the additive specimen is 151.0 MPa and 10.4%, respectively.

Key words:Solid-state additive manufacturing; 6061 aluminium alloy; Microstructure; Mechanical properties; Precipitated phase