فهرست نشریات علمی دسترسی آزاد ایران

 This study examined the microstructure and corrosion characteristics of friction stir welded DP600 steel. Two different combinations of rotational and transverse speeds were used for the welding process: 700 rpm and 80 mm/s (700-80 sample), and 1000 rpm and 20 mm/s (1000-20 sample). Microstructural observations demonstrated the formation of a mixture of polygonal ferrite, Widmanstatten ferrite (WF), bainite, and ferrite-carbide aggregate in the stir zone (SZ) of the welded samples. Furthermore, a coarser microstructure and a higher fraction of WF and bainite were observed in the 1000-20 sample. Electron backscatter diffraction analysis revealed areas with higher kernel average misorientation values around the martensite islands in the DP600 steel and within the bainite and WF in the welded samples. Formation of bainite and WF in the SZ of the welded samples resulted in the increase of the fraction of low-angle grain boundaries from  5% in the DP600 steel to  60% in the 1000-20 sample. The study further investigated the corrosion behavior using polarization, electrochemical impedance spectroscopy, and immersion tests. The results indicated that the corrosion performance of the 700-80 sample was similar to that of the original DP600 steel, whereas the 1000-20 sample exhibited a degradation in corrosion behavior with a corrosion rate approximately twice that for the other two samples, mainly due to its coarser microstructure.