Structure and Properties of Friction Stir Weld Joints of Structural Steel

In the present study, structural steel plates of thickness 3 mm were welded using friction stir welding with the help of a tungsten carbide tool using welding speed of 20 mm/min and tool rotation speed of 508 rpm. The friction stir weld joints were characterized in respect of microstructure, hardness and tensile properties. The stir zone of the weld revealed the refined grain structure of ferrite, fine pearlite and martensite were also confirmed by XRD. Further, the hardness distribution of the weld joint exhibited higher hardness at the weld nugget than base metal and heat affected zone. The weld sample exhibited higher strength and lower ductility than the base metal. The tensile properties of the all weld samples taken from longitudinal direction were better than those taken from transverse direction. Influence of post weld heat treatment of FSW joints of steel on microstructure and mechanical properties was also investigated.