A comparative study on friction stir welding of tailor weld blanks.

The effect of single-pass (SP) and double-pass (DP) friction stir welding (FSW) on metallographic and mechanical properties of joints was investigated in this study. Uniform temperature distribution across the weld cross-section was obtained during double-pass FSW (DP-FSW). SEM and EDS analyses showed an increase in the fraction of second phase particles (SPPs) and the formation of new SPPs by DP-FSW. An increase in hardness values by 13.3% and a severe decrease in joint efficiency by 46.7% were observed by DP-FSW. Fractography examination of fractured surfaces of welded specimens showed a quasi-cleavage and ductile mode of failure in SP and DP joints, respectively. The potentiodynamic polarisation test of base metal and welded specimens indicated the high corrosion resistance of welded specimens. [ABSTRACT FROM AUTHOR]