A review on friction stir-based channeling

Friction stir-based channeling is a solid-state processing encompassing the friction stir channeling (FSC) and its variants. In one manufacturing action, the FSC delivers a subsurface internal closed channel in a monolithic plate with no length limitation. The unique characteristics of theses internally closed channels produced with FSC can fit the demand from several industrial fields, namely lightweight structurally stiffened panels and applications where high power density requires highly efficient thermal management systems, such as power electronics and electric vehicles-based transportation. This first review on the FSC and its variants encompasses a systematic and comprehensive understanding on physical properties, including thermal performance and channel manufacturability applied to different engineering materials. The discussion is emphasized on working principle of channel formation, tool design, influence of process parameters, geometrical characterization, mechanical properties, hardness field and microstructural features correlated with mechanical properties. It can be summarized that novel processing of channels by FSC enhances the thermal performance compared to conventional fabrication techniques. FSC can produce complex path channels with various sizes, shapes and surface finishing. Precise control on process parameters and material flow governs the channel formation that subsequently influences thermal and mechanical performances of the channels. FSC has been applied to different range of thermal management systems and has potential for many demanding existent applications and enabling new high-performance products. From the initial FSC concept based on a shoulder-workpiece clearance, to the most recent solutions, such as the stationary shoulder FSC, and the no-tilt-angle and no-shoulder-workpiece clearance, allowing the manufacturing of large size channels, leaving the processed surface at its original quota and ready to be used. A significant leap is introduced with the Hybrid FSC enabling simultaneous welding and channeling, of similar and dissimilar metal components, and therefore enhancing design opportunities for even more competitive solutions.