Effects of Friction Stir Welding on the Properties and Microstructure of Binary Brasses: a Review

This literature review aims to critically and thoroughly analyze the effects of friction stir welding (FSW) on the microstructural and mechanical properties of binary brasses. Through a comprehensive analysis of specialized literature, the main metallurgical mechanisms involved were discussed, including dynamic recrystallization, intermetallic compounds formation, and the evolution of microstructural gradients across the affected zones (Stir Zone, TMAZ, and HAZ). The influence of process parameters notably tool rotational speed, feed rate, axial force, and tool geometry, was directly correlated to the microstructural evolution and joint quality. Fracture modes and failure mechanisms were analyzed, highlighting that crack nucleation preferentially occurs in regions with severe hardness gradients and/or intermetallic presence. The comparison between similar and dissimilar joints revealed that the latter present significantly greater challenges, particularly related to the formation of continuous intermetallic layers and thermal asymmetry during processing. Finally, consolidated advances, persistent challenges, and prospects for developing technological solutions that ensure the structural integrity and mechanical performance of friction-stirred binary brass joints are discussed.