A Novel Flow-Balanced Friction Stir Channeling Technology: High Rectangularity Design and Channel Formation Mechanisms

Abstract

Friction stir channeling (FSC) presents a promising approach for achieving continuous channels in heat exchangers, which are considered as leading candidates for high-efficiency thermal dissipation. However, the irregular cross-sectional shape of prepared channels induces stress concentration and compromises the load-bearing capacity and structural integrity. Herein, flow-balanced FSC (FB-FSC) technology is proposed to fabricate channels with enhanced rectangularity. This technique allows for precise control over the shape, path, position, and arrangement of the channels. The channel formation in FB-FSC is affected by material overflow–reflux behaviors and stick–slip conditions. Material overflows onto the shoulder due to shearing and extraction then refluxes under axial pressure to close the channel. The material stuck to the probe rotates accordingly and is pulled out into the channel cavity to form a deposition layer. By regulating channel formation mechanisms, channel rectangularity of 90.8%, continuous formation of 14 m, minimum spacing of 2 mm, variable arc radius, and gradient distribution are directly achieved via FB-FSC. The FB-FSC technology enables the efficient formation of cooling channels with high quality, which is significant for the design of heat exchangers to realize desired performances.