Experimental Analysis and Finite Element Modeling of the Lateral Friction Surfacing Process
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2022
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Lateral friction surfacing is a novel method of friction surfacing for solid-state metal deposition, in which the radial surface of the rotating consumable tool is forced into the substrate surface, facilitating material transfer. Frictional heat enables plastic deformation, which results in depositing the consumable material on the substrate surface, and a layer of tool material is transferred from the consumable rod to the substrate surface as the tool moves across. The process is carried out at temperatures below the melting point of the consumable material, resulting in a solid-state deposition process. In this method, there is no external source of heat energy, and all the heat energy required in this method is generated by friction. This technique is an excellent alternative to creating thin and ultra-smooth metallic deposit layers for repairing damaged surfaces or improving corrosion and wear resistance. Also, there is no flash formed in this technique which reduces material consumption.In this study, a comprehensive assessment through conducting real-time force measurement, surface roughness measurement, hardness testing, corrosion performance analysis, optical microscopy, infrared thermography, scanning electron microscopy, and energy-dispersive X-ray spectroscopy was performed to characterize the lateral friction surfacing of various materials. Furthermore, the LFS process was investigated via thermo-mechanical modeling using ABAQUS software to analyze the mechanical and thermal responses. In order to evaluate the model, an experimental study using the same materials and process parameters was conducted.
The results showed that the lateral friction surfacing approach is capable of producing coating layers with complete coverage, roughness values of less than 1 µm, and coating thickness values as low as 16 µm. Furthermore, this technique results in a deposition process with lower generated process temperatures than conventional friction surfacing, which mitigates the thermal impacts on the microstructures, mechanical properties, and metallurgical characteristics of the deposits. The finite element modeling proved that this novel technique generates low process temperature localized in a small area, and the temperature rapidly decreases as the distance from the processing zone slightly increases. The quality of the fabricated deposits was found to be dependent on several important process parameters such as pressing force, table traverse speed, spindle speed, and tool/substrate materials. Therefore, these parameters can be utilized as the controlling process parameters to achieve the desired quality. This study revealed that high input energy provided by high normal forces and tool rotational speeds might result in failure in the deposition process of materials with lower thermal conductivity and melting point, which emphasizes on limitations for the process parameters during the process. On the other hand, increasing the input energy by adopting higher forces and rotational speeds may lead to deposition of materials with higher melting points.
The cross-sections SEM analysis of various deposits was conducted, and results exhibited a clear interface without any unbonded regions between deposits of some materials such as AA2011 and AA6061 and the steel substrate; however, cracks and unbonded regions at the interface of AA7075 deposit and steel substrate were observed. Moreover, the SEM results revealed no elemental diffusion of consumable materials to the substrate, which indicates that the LFS process temperature was low enough to avoid plasticizing the substrate and intermixing between the consumable material and substrate. The EDS analysis showed that excess Si in the plasticized consumable material results in large Si-rich particles forming in the deposition of different aluminum alloys, such as AA6061 and AA6063. Moreover, the EDS analysis revealed the presence of a large amount of Fe in most of the coatings fabricated on steel substrates, indicating that the substrate material was rubbed off during the LFS process due to high tool speed and force at the tool/substrate interface, and the substrate material was transferred to the deposits.
Furthermore, the multilayer deposition of AA6061 onto AISI 1018 through the lateral friction surfacing process was performed to assess the potential application of this technique for fabricating multilayer deposits and additive manufacturing purposes. The multi-pass deposition of AA6061 through LFS did not result in a trend of increasing coating thickness due to the formation of a reverse material transferring process from the coating to the radial surface of the rod.
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Mechanical engineering, Additive Manufacturing, Friction Deposition, Material Characterization, Material Processing, Metal Coatings, Solid-State Deposition
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171 pages
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