Effect of Tool Protrusion in Thick-layer Additive Friction Stir Deposition of 6061Aluminum Alloy

doi:10.3969/j.issn.1004-132X.2026.10.010

Abstract

Abstract:

To improve the efficiency of additive friction stir deposition， a thick-layer process was developed to investigate the effect of tool protrusions on the material flow， microstructure evolution， and mechanical properties of the deposited layer. The results show that the stabilized temperature and uniform surface of the deposited layer ensure high quality forming. The tool protrusions lead to the formation of a tool protrusion-effective zone （TPEZ） and a tool protrusion non-effective zone （TPNZ） within the deposition， materials in the TPEZ exhibit a vortex-like flow with a bowl-shaped profile， while those in the TPNZ show stable laminar flow. The grains in the deposited layer are significantly refined compared with the raw material， and the high strain rate and short-term high temperature in the TPEZ inhibit the grain recrystallization process， while the TPNZ achieve sufficient dynamic recrystallization under moderate conditions. In terms of mechanical properties， the TPNZ showed a 40.8% decrease in tensile strength but a 115% increase in elongation after fracture compared with the feedstock rod. In contrast， the TPEZ exhibited premature fracture due to high dislocation density and lattice distortion induced by rotational-extrusion-dominated deformation， with a tensile strength and elongation of only 141.1 MPa and 5.7%， respectively.

Key words: additive friction stir deposition, thick-layer, tool protrusion, microstructure evolution, mechanical properties

摘要：

为提高搅拌摩擦增材制造效率，开发了一种高沉积层厚工艺，探究了工具凸台对沉积层内材料流动、组织演变与力学性能的影响。研究结果表明，沉积层稳定温度和均匀表面确保了高质量成形；工具凸台导致沉积层内形成凸台作用区与非作用区，凸台作用区材料呈碗口状涡旋流动，非作用区表现为稳定层流；沉积层晶粒相比原料均显著细化，凸台作用区因高应变率与短时高温，抑制晶粒再结晶过程，而非作用区在适中条件下实现了充分的动态再结晶；在性能方面，与原料棒相比，非凸台作用区抗拉强度下降了约40.8%，但断后伸长率显著提高了约115%，而凸台作用区旋转挤压的成形模式诱发高位错密度与晶格畸变导致拉伸中过早断裂，抗拉强度与断后伸长率仅为141.1 MPa与5.7%。

关键词: 搅拌摩擦沉积增材, 高层厚, 工具凸台, 组织演变, 力学性能

CLC Number:

TP453

WANG Shuaipu, ZHAO Lei, WANG Yunlong, CHEN Qi, WANG Junhong, WU Zhilin. Effect of Tool Protrusion in Thick-layer Additive Friction Stir Deposition of 6061Aluminum Alloy[J]. China Mechanical Engineering, 2026, 37(10): 2476-2483.

王帅普, 赵磊, 王云龙, 陈琦, 王俊红, 吴志林. 6061铝合金厚层搅拌摩擦增材工具凸台的影响[J]. 中国机械工程, 2026, 37(10): 2476-2483.

Figures/Tables 16

Tab.1 Composition of the 6061-T6 aluminum alloy

成分	Si	Fe	Cu	Mn	Mg	Cr	Zn	Ti	Al
质量分数	0.55	0.35	0.35	0.05	1.0	0.25	0.15	0.10	其余

Fig.1 Microstructure of the 6061-T6 feedstock

Tab.2 Mechanical properties of 6061-T6 aluminum alloy

屈服强度	抗拉强度	断后伸长率	硬度
275 MPa	346 MPa	13.9%	113HV

Fig.2 Schematic of the AFSD process

Fig.3 AFSD setup and macroscopic view of the deposit

Fig.4 Schematic of the sample sectioning for the deposited layer

Fig.5 Temperature evolution of the deposited during AFSD

Fig.6 3D morphology of the AFSD deposit

Fig.7 Observation of material flow within the deposited layer

Fig.8 Inverse pole figure， grain size distribution， and misorientation angle statistics of grains in the deposited layer

Fig.9 KAM and GND density in the TPEZ and TPNZ

Fig.10 Distribution and proportion statistics of grain types in the TPEZ and TPNZ

Fig.11 Schematic of the grain evolution mechanism in different intra-layer regions

Fig.12 Distribution of Vickers hardness in different regions of the deposited layer

Fig.13 Tensile properties of the feedstock and different regions of the deposited layer

Fig.14 Morphology observation of tensile fracture from different regions

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