Analysis of the Influence Of Friction Stir Welding on the Microstructure and Mechanical Properties of Alloy UNS-C27200 (CU-ZN)

Abstract

The copper alloy UNS-C27200 is a binary brass, composed of 38wt%Zn, beeing one of the most used in the industry. The union of Cu-Zn alloys by conventional welding by fusion in thin plates presents several challenges. The Friction Stir Welding (FSW) process performs the union of two, or more materials, through a rotating tool that travels throughout the welding region. One the great advantages of FSW is working below the melting point of the material, which reduces the change in the microstructure and properties of the material, when compared to conventional welding processes. Due to the lack of research on FSW process in lap brass joints with thin thicknesses, the present work aims to expand these studies in order to contribute to future research. Eight conditions were evaluated, varying rotation and welding speed. In the best results by visual inspection, analyzes of microstructure, temperature, microhardness and mechanical strength were performed. The better welding results were obtained with ω=1050 rpm and ν=20 mm/min. There was reduction of approximately 50% between Stir Zone and Base metal. The mechanical strength was affected by the pin hole resulting from the process. The microstructure revealed a homogeneous mixture in the stir zone and no defects were detected.

Keywords

• Friction stir welding - FSW
• lap joint
• UNS-C27200
• mechanical behavior