Investigation of weldability of martensitic and ferritic stainless steels with themselves and each other by friction stir welding

ABSTRACTPhD ThesisINVESTIGATION OF WELDABILITY OF MARTENSITIC AND FERRITICSTAINLESS STEELS WITH THEMSELVES AND EACH OTHER BY FRICTION STIRWELDINGErtuğrul ÇELİKFırat UniversityGraduate School of Natural and Applied SciencesDepartment of Metallurgy Education2006, Page : 66In this study, its investigated bonding of ferritic satinless stell that contains martensitevia friction stir welding. Stainless steel was cast into plates and welded as cast. While weldingspeed was kept constant, three different tool rotation speeds, 350, 450, and 550 rpm, were used.After welding mechanical behaviors of the joints were determined by tension tests. Themicrostructure of the weld region was examined by optical microscopy and SEM and handnessacross the weld region was measured by a microhardness tester.As a result, it wass seen that 4 different region occoured, tension strenght was maximumat optimum rotation speed which was 450 rpm, the hardness increased in fine grained region. Itwas understood that stainless steel with martensite could be joined by firction stir weldingsafely.Keywords : Friction stir welding, stainless steel, welding tool.