2707 hyper-duplex stainless steels (HDSSs) contain high contents of alloying elements (Cr, Ni, Mo and N), which may shorten the incubation period and promote both nucleation and growth of sigma (σ) phase. 2707 HDSS w...2707 hyper-duplex stainless steels (HDSSs) contain high contents of alloying elements (Cr, Ni, Mo and N), which may shorten the incubation period and promote both nucleation and growth of sigma (σ) phase. 2707 HDSS was first aged at different temperatures and periods of time for drawing the time-temperature-transformation profiles. The results identified the main precipitates as σ phase, with nose temperature of about 950℃. Also, 2707 specimen was aged at 950℃ for a short time, and the morphology, distribution and amount of σ phase were examined through the scanning electron microscope and X-ray diffraction,σ phase was initially formed at the boundaries of ferrite and austenite and then transformed through the eutectoid reaction (α→σ+γ2). Finally, the precipitation and growth of σ phase in 2707 steels aged at nose temperature for a short period reduced the corrosion resistance and deteriorated the mechanical properties, and the corresponding reason was further analyzed.展开更多
Polarization curves and mass losses of SAF3207 hyper-duplex stainless steel under various conditions were measured.The damaged surfaces after erosion–corrosion tests were characterized by scanning electron microscopy...Polarization curves and mass losses of SAF3207 hyper-duplex stainless steel under various conditions were measured.The damaged surfaces after erosion–corrosion tests were characterized by scanning electron microscopy.The results showed that an increase in flow velocity could enhance the electrochemical corrosion and consequently decrease the passivation properties of the steel.The erosion–corrosion damage of the samples increased substantially when the flow velocity exceeded the critical value of 4 m·s^-1.The mass loss rate increased as the sand content increased,reaching a maximum at 7 wt%sand content,corresponding to the most severe electrochemical corrosion damage.When the sand content was increased further,however,the mass loss rate decreased and then tended stable.The mass loss was divided into incubation,sustained,and stationary periods,with a maximum mass loss rate of 12.97 g·h^-1·m^-2 after an erosion period of 2.5 h.The erosion–corrosion mechanism was investigated in detail.展开更多
基金National Natural Science Foundation of China (Grant No. 51371123)Shanxi Province Science Foundation for Youths (201601D202033).
文摘2707 hyper-duplex stainless steels (HDSSs) contain high contents of alloying elements (Cr, Ni, Mo and N), which may shorten the incubation period and promote both nucleation and growth of sigma (σ) phase. 2707 HDSS was first aged at different temperatures and periods of time for drawing the time-temperature-transformation profiles. The results identified the main precipitates as σ phase, with nose temperature of about 950℃. Also, 2707 specimen was aged at 950℃ for a short time, and the morphology, distribution and amount of σ phase were examined through the scanning electron microscope and X-ray diffraction,σ phase was initially formed at the boundaries of ferrite and austenite and then transformed through the eutectoid reaction (α→σ+γ2). Finally, the precipitation and growth of σ phase in 2707 steels aged at nose temperature for a short period reduced the corrosion resistance and deteriorated the mechanical properties, and the corresponding reason was further analyzed.
基金supported by the Major Special Program of Fujian Province, China (No. 2017HZ0001-2)the Joint Innovative Project for Industrial Technology of Fujian Province, China (No. FG-2016001)+1 种基金the Special Funds for Marine High-Tech Industry Development of the Fujian Province of China (High-Tech of Ocean and Fisheries of Fujian Province 2014 No. 14)the Scientific Research Projects for Young Teachers of Education Department of Fujian Province, China (No. JAT160066)
文摘Polarization curves and mass losses of SAF3207 hyper-duplex stainless steel under various conditions were measured.The damaged surfaces after erosion–corrosion tests were characterized by scanning electron microscopy.The results showed that an increase in flow velocity could enhance the electrochemical corrosion and consequently decrease the passivation properties of the steel.The erosion–corrosion damage of the samples increased substantially when the flow velocity exceeded the critical value of 4 m·s^-1.The mass loss rate increased as the sand content increased,reaching a maximum at 7 wt%sand content,corresponding to the most severe electrochemical corrosion damage.When the sand content was increased further,however,the mass loss rate decreased and then tended stable.The mass loss was divided into incubation,sustained,and stationary periods,with a maximum mass loss rate of 12.97 g·h^-1·m^-2 after an erosion period of 2.5 h.The erosion–corrosion mechanism was investigated in detail.
