Analyzing microstructural evolution and wear behavior of friction stir welded dissimilar joints of SS304 and 2024-T3 Al alloy

•Proper heat input, plastic deformation, and controlled stirring foster grain refinement.•Controlled plastic deformation integrates SS particles into the Al matrix smoothly.•FeAl3 and Fe3Si layers on SS particles in the Al matrix boost hardness.•Increased surface hardness leads to a reduced wear rate. This study employs friction stir welding (FSW) on SS304 and 2024-T3 Al alloy to enhance the microstructure and wear resistance of the resulting joint. FSW yielded an ultra-refined microstructure with a 4.2 µm average grain size, achieved through severe plastic deformation. In the dry sliding reciprocating wear test, specific wear rates for the base materials Al alloy, SS304, and FSWed specimens were determined to be 9.251 × 10−17 m3/Nm, 4.824 × 10−17 m3/Nm, and 2.072 × 10−17 m3/Nm respectively. Notably, the FSWed specimen exhibited an improved wear behavior, showing increased stability in the tribolayer and a reduced occurrence of severe delamination. The enhancements result from grain refinement and the inclusion of finely dispersed stainless steel (SS) particles, comprising around 5–6 % of the material, with an average grain size of 1 µm to 1.2 µm, within the stir zone (SZ), encased by thin layers of FeAl3 and Fe3Si. These factors contribute to the heightened microhardness of the specimen and a decrease in wear rate.