Abstract: The study was conducted to investigate the microstructure and microhardness properties of the friction stir welded zones and shielded metal arc welded. Microstructural analysis of the weld was carried out using optical microscopy. Under FSW process base metal microstructure fully changed. Different heat inputs were obtained using a fix travel (welding) speed in combination with several spindle speeds. Heat input during welding process had a significant influence on the microstructure and mechanical proprieties in the various weld regions.it can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone hardness increase.