In the present study, microstructural and texture development, mechanical properties and corrosion behavior of dissimilar jointing between austenitic stainless steel AISI 316 and low carbon steel t 37 by friction stir welding has been investigated. The welding was carried out with rotational speeds of 400,600,800 rpm and linear speeds of 50,100,150 mm/min. The microstructure was characterized by scanning electron microscopy (SEM) and optical microscopy. Possible phase transformations were determined using X-ray diffraction technique and electron diffraction spectroscopy. Also, changes in texture of the joints were studied using electron backscatter diffraction (EBSD) technique. Tensile test, shear punch test and microhardness measurements were conducted to evaluate the mechanical properties of the joints. Also, corrosion behavior of the joints were assessed using Tafel polarization and Immersion tests. The results showed that using friction stir welding, joints without defects were produced. In addition, no carbide and brittle phases were detected at the joining boundary. Microstructural investigations showed that the significant decrease in grain size was occurred in the stir zone of the austenitic stainless steel for sample welded at rotational speed of 600 rpm and linear speed of 50 mm/min. EBSD technique showed texture has been modified to direction of compact planes and orientations. Tensile test results demonstrated that failure was occurred in the weld metal for samples welded at rotational speed of 400 rpm for all linear speeds. Whereas, failure was occurred in the St 37 base metal for samples welded at rotational speeds of 600,800 rpm and linear speeds of 50,100,150 mm/min. According to the shear punch test, the highest ultimate shear strength as well as yield shear strength was achieved for sample welded at rotational speed of 600 rpm and linear speed of 50 mm/min, while the mentioned sample showed the least elongation. In addition, the highest microhardness was measured in the stir zone of austenitic stainless steel sample welded with the above mentioned welding condition. The results of corrosion behavior evaluation showed similar corrosion behavior as of St 37 base metal, but the corrosion potential and the corrosion current density of weld metals were higher in comparison to St 37 base metal. Also, the results of immersion test demonstrated that the stir zone of St 37 steel side had the lowest resistance to pitting due to increase of dislocations density and grain boundaries in this region. Keywords : dissimilar joint, austenitic stainless steel AISI 316, low carbon steel, friction stir welding, EBSD.
