Effect of Welding Heat Input on the Microstructure and Mechanical Properties of Dissimilar Friction Stir-Welded Copper/Brass Lap Joint

Dissimilar lap welded joints of copper and brass metals were fabricated by friction stir welding (FSW) method at various welding heat inputs. The effect of welding heat inputs on the microstructure and mechanical properties of overlap welded joints at at two different join configurations (i.e. Advancing side and Retreating side joint configurations) was investigated. In both joint configurations, copper and brass plates are located on the top and bottom plates, respectively. Tensile-shear and vicker's microhardness tests were conducted to evaluate the mechanical properties of dissimilar lap welded joint. In order to analysis of microstructure and fracture surface of lap welded joints, optical microscope (OM) and scanning electron microscope (SEM) were used. The ontained results showed that the weld surface of samples was appeared without groove defects, low superfluous flash and oxidation, when the welding heat input is increased. Onion ring pattern characterized by the stack of copper and brass metals is identified in the weld nugget zone (WNZ) where metal flow structures can be observed. With decreasing welding heat input, tensile-shear strength increased at both joint configurations. The highest hardness was exhibited in the WNZ with increasing welding heat input in both joint configurations.