Elucidating role of sheets mutual position and copper interlayer in FSW of dissimilar Ti6Al4V-SS316L lap joints: Metallurgical and mechanical characterizations

Technological advancements catering to the specific requirements of different industries have led to a rise in the use of multi-material components. Combining titanium and stainless steel can reduce the weight of components used for many industrial applications, making it a popular choice. The present investigation compares Ti6Al4V/ SS 316 L friction stir welded (FSW) lap joints' metallurgical and mechanical properties as a function of velocity ratio, sheets' mutual position, and the presence of a Cu interlayer. The process mechanics and the impact of different strategies on intermetallic (IMC), grain morphology, intermittent phases, joint resistance, and microhardness are discussed. Successful FSW lap joints of SS 316 L/ Ti6Al4V, utilizing SS 316 L as the upper plate and a Cu interlayer, have been documented and deliberated for the first time in the present study. These specimens demonstrated immaculate joints for all the processing velocity ratios owing to superior mechanical interlocking offered by distinguished extruded hook accompanied by comparatively lean IMC layers affecting tensile shear strengths.