Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis so...Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis software was used for quantitative analysis.The variation of mechanical properties before and after overtemperature treatment was tested.Results show that the Ti_(2)AlNb alloy consists of B2 phase and lamellar O phase before and after overtemperature treatment.After overtemperature treatment,partial B2 phase is transformed into the O phase,and the lamellar structure of O phase suffers discontinuous coarsening and spherolization.The coarsening degree is increased with the increase in temperature and prolongation of treatment time,and O phase content is also gradually increased.The microhardness and tensile properties of Ti_(2)AlNb alloys at room and high temperatures are decreased with the increase in temperature and prolongation of treatment time,and the high-temperature tensile strength exhibits relatively larger decrement.An obvious linear relationship exists between microhardness and O phase content.Both the microhardness and the O phase content are important parameters to evaluate the overtemperature service damage degree of precision-cast Ti_(2)AlNb alloy.展开更多
After research on a 2000t/h subcritical forced-circulation balanced ventilation were applied boiler and the structure and operation of its auxiliary system builds up this heat transfer model of a superheater's pip...After research on a 2000t/h subcritical forced-circulation balanced ventilation were applied boiler and the structure and operation of its auxiliary system builds up this heat transfer model of a superheater's pipe wall and analyze the effect of primary factors on the overtemperature of the pipe wall. Fault tree structure was used to uncover the multiplayer logic between the overtemperature of the superheater's pipe wall and the faults.展开更多
文摘Microstructure evolution of precision-cast Ti_(2)AlNb alloys after overtemperature treatments at 750 and 850℃ was investigated by optical microscope and scanning electron microscope,and Image J metallurgy analysis software was used for quantitative analysis.The variation of mechanical properties before and after overtemperature treatment was tested.Results show that the Ti_(2)AlNb alloy consists of B2 phase and lamellar O phase before and after overtemperature treatment.After overtemperature treatment,partial B2 phase is transformed into the O phase,and the lamellar structure of O phase suffers discontinuous coarsening and spherolization.The coarsening degree is increased with the increase in temperature and prolongation of treatment time,and O phase content is also gradually increased.The microhardness and tensile properties of Ti_(2)AlNb alloys at room and high temperatures are decreased with the increase in temperature and prolongation of treatment time,and the high-temperature tensile strength exhibits relatively larger decrement.An obvious linear relationship exists between microhardness and O phase content.Both the microhardness and the O phase content are important parameters to evaluate the overtemperature service damage degree of precision-cast Ti_(2)AlNb alloy.
文摘After research on a 2000t/h subcritical forced-circulation balanced ventilation were applied boiler and the structure and operation of its auxiliary system builds up this heat transfer model of a superheater's pipe wall and analyze the effect of primary factors on the overtemperature of the pipe wall. Fault tree structure was used to uncover the multiplayer logic between the overtemperature of the superheater's pipe wall and the faults.
