Deciphering the interdependent impact of process parameters in friction stir welding-Part I: an overview of the challenges and way forward

The versatility of FSW as a joining technique for ferrous and non-ferrous metals depends on fine-tuned process parameters. To date, reports of mixed success exist in the literature on apt-tuning these parameters due to the elusive knowledge of their interdependencies. Hence, this paper aims to unravel the linkages in selecting apt process parameters vis-a-vis the FSW's tool and workpieces' properties. First, the study identifies bottlenecks hindering generalizations of the impact of process variables. Then, through data abstraction and exploratory analyses of copper and aluminium alloy welds, it statistically reviews the process parameters that produced defect-free welds, highlighting linkages within the process parameters, workpiece properties, and the ensued joint properties. The result shows the mastery of the art of FSW over the past decades, albeit with inept scientific links between the workpieces' properties and optimal process parameters. This suggests the need for in-depth comparative studies on pure metal joints.