Challenges, process requisites/inputs, mechanics and weld performance of dissimilar micro-friction stir welding (dissimilar μFSW): A comprehensive review

Dissimilar micro-friction stir welding (dissimilar mu FSW) can be a preferred choice for joining dissimilar materials having thickness <= 1000 mu m. The technique's potential applications are in miniaturized components, where the inherent benefits of the process, such as low temperature, low distortion, and clean joining, are advantageous compared to fusion welding. However, the challenges associated with dissimilar mu FSW hinder its full potential applications in the relevant industries. The challenges are particularly a combination of two different characteristics of the process (i) the complexities of simultaneously fulfilling the dissimilar materials' demands due to the vast differences in the two materials' mechanical and thermal properties and (ii) the problems due to reduced sheet thickness. In this regard, the present work is a comprehensive and timely review of the research works done on dissimilar mu FSW targeted at easily acquainting the research community about the know-how and the state of the art of the process. The review is broadly divided into three crucial parts: the process inputs/requisites, process mechanics, and process performance. The details about the mu FSW tool, process parameters, and relative sheet positioning are discussed under the heading process inputs/requisites. Concerning the process mechanics, the intermetallic compound formation, defect generation, and material mixing are discussed. The joints' resulting performance is shown by detailing the essential properties such as formability, residual stresses, fatigue, hardness, and tensile strength. Additionally, several future research directions are presented at the end of this critical review to motivate further improvements in this joining technique and instigate its utility in relevant industries.

Automated summary

Dissimilar micro-friction stir welding is a preferred choice for joining dissimilar materials with thickness <= 1000 μm, especially in miniaturized components. However, challenges such as differences in mechanical and thermal properties of the materials, as well as issues related to reduced sheet thickness, hinder its full potential applications.