Dissimilar joints are growingly prevailing modern design of a wide range of equipment, especially inpetrochemical, oil, and gas industries. In this research, UNS 43000 ferritic stainless steel and UNS 32304duplex stainless steel were welded by a laser beam welding process in butt joint configuration, andmicrostructural evolutions and phase formation during laser welding were investigated using electronbackscatter diffraction. The effect of heat input on the tensile properties and fracture behavior of thewelded joint was also studied. It was observed that irregular grain orientations implied a relatively weaktexture in the laser-welded joint. It was also found that three different phases, i.e.,a(with bcc crystalstructure),c(with fcc crystal structure), and Cr7C3(with hcp crystal structure), appeared in different areasof the welded joint. The predominant phase in the welded metal and the heat-affected zone wasa(bcc).Also, despite the concentrated heat source on laser beam welding and the associated short cooling times, nomartensitic structure was formed in these areas. By moving toward UNS 32304 base metal, morec(fcc)phase was formed in the welded metal, which could be attributed to the higher concentration of austenitestabilizer elements, e.g., Ni and N, at UNS 32304 side. The presence of distinguished forms of austenite withfcc crystal structure, namely grain boundary allotriomorphic austenite and wedge-shaped Widmansta ̈ttenaustenite, was seen mainly at ferrite grain boundaries and ferrite grain interior, respectively.
