Key Takeaways & Executive Findings
- •• Multi-layer multi-pass FRAM successfully fabricates aluminum alloy components with complex geometries, overcoming the single-pass width limitation. • Mechanical interlocking and recrystallization in overlapped zones enhance bonding, achieving tensile strength >90% of single-pass samples. • Surface grooves from overlapping are filled by material flow in subsequent layers, ensuring dense microstructure and excellent mechanical properties. • This solid-state additive method paves the way for large-scale, high-performance aluminum alloy components in aerospace and transportation.
Abstract
At present, the emerging solid-phase friction-based additive manufacturing technology, including friction rolling additive manufacturing (FRAM), can only manufacture simple single-pass components. In this study, multi-layer multi-pass FRAM-deposited aluminum alloy samples were successfully prepared using a non-shoulder tool head. The material flow behavior and microstructure of the overlapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum alloys. The results showed that a mechanical interlocking structure was formed between the adjacent layers and the adjacent passes in the overlapped center area. Repeated friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone, which made the recrystallization degree in the left and right edge zones of the overlapped zone the highest, followed by the overlapped center zone and the non-overlapped zone. The tensile strength of the overlapped zone exceeded 90% of that of the single-pass deposition sample. It is proved that although there are uneven grooves on the surface of the overlapping area during multi-layer and multi-pass deposition, they can be filled by the flow of materials during the deposition of the next layer, thus ensuring the dense microstructure and excellent mechanical properties of the overlapping area. The multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.
1. Introduction
In recent years, aluminum alloys have been widely used in aerospace and rail transit because of their light weight, corrosion resistance, high specific strength, and good specific stiffness [1–2]. Replacing the traditional combined aluminum alloy components with large integral aluminum alloy components not only reduces the weight by 15%–20%, but also significantly improves the service life and reliability of the components [3]. Additive manufacturing (AM), which is based on the principle of layer-by-layer material deposition [4–5], is an ideal method for the preparation of large-scale aluminum alloy load-bearing components. Compared with the traditional material machining technology, it is a “bottom-up” material deposition [6–7] that can meet the high-performance and rapid manufacturing of large parts in high-end equipment manufacturing industries such as aerospace, weapons and equipment, and shipbuilding industry [6].
Considering the step-by-step and layer-by-layer accumulation characteristics of AM, it is necessary to perform thousands of multi-layer and multi-pass depositions to prepare large aluminum alloy components. Traditional melting additive technology presents many problems when depositing multi-layer and multi-pass. For example, Cui et al. [8] deposited multi-layer and multi-pass 2319 aluminum alloys using wire oscillating laser AM technology, and the results showed that pore defects were found in the sixth interlayer area, which was caused by poor heat dissipation conditions and heat accumulation.
Friction stir welding (FSW) is a solid-state welding technology invented by the Welding Institute in 1991, and it has been widely used in joining light alloys such as aluminum alloy and magnesium alloy [9–10]. On the basis of FSW, in recent years, a variety of solid-phase AM technologies have been developed, such as friction stir AM (FSAM) [11], additive friction stir deposition (AFSD) [12–15], wire-based friction stir AM (W-FSAM) [16], friction stir powder AM (FSPAM) [17], friction-forward tubular AM (FFTAM) [18], and friction rolling AM (FRAM) [19]. Among them, FRAM is a new solid-phase AM method based on friction and rolling, which can realize friction heat generation, continuous feeding, and material forming simultaneously. Different from the accumulative roll bonding (ARB) [20] in which two thin plates are repeatedly rolled and welded at a certain temperature, the roller of ARB only exerts downward pressure on the material, but the tool head of FRAM generates heat by friction with the material and drives the plastic material to flow. The high-speed rotating FRAM tool head contacts with the surface of the material and the feed strip, and generates a lot of heat through friction, which softens the material. The softened material undergoes serious plastic deformation under the action of the rotation of the tool head and rolling pressure, and then the material flow...
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Haibin Liu, Run Hou, Chenghao Wu, Ruishan Xie, Shujun Chen (2025). Multi-layer multi-pass friction rolling additive manufacturing of Al alloy: Toward complex large-scale high-performance components. Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报). https://doi.org/10.1007/s12613-024-2945-1
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Frequently Asked Questions
What is friction rolling additive manufacturing (FRAM)?
FRAM is a solid-phase additive manufacturing method that uses friction and rolling to generate heat, soften material, and deposit layers. It enables simultaneous heat generation, material feeding, and forming, and can produce large components without melting.
How does multi-layer multi-pass FRAM overcome the limitation of deposition width?
By overlapping adjacent layers and passes, FRAM can build components wider than a single pass. The material flow during subsequent passes fills surface grooves, ensuring dense microstructure and strong bonding, thus enabling large-scale fabrication.
What are the mechanical properties of the overlapped zones in multi-layer multi-pass FRAM?
The tensile strength of the overlapped zones exceeds 90% of that of single-pass deposition samples, indicating excellent mechanical integrity. This is attributed to mechanical interlocking and recrystallization in the overlapped regions.
What materials were used in this study?
The study used hybrid 6061 and 5052 aluminum alloys to investigate material flow and microstructure in the overlapped zones during multi-layer multi-pass FRAM deposition.
What is the significance of this research for industrial applications?
This research demonstrates that multi-layer multi-pass FRAM can produce large-scale, high-performance aluminum alloy components with complex geometries, which is crucial for aerospace, rail transit, and other high-end manufacturing sectors.
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