The effect of solution annealing temperature ranging from 950 to 1 200 ℃ on the microstructure and corrosion performance of duplex stainless steel (DSS) 2204 were investigated. The proportion of the ferrite phase i...The effect of solution annealing temperature ranging from 950 to 1 200 ℃ on the microstructure and corrosion performance of duplex stainless steel (DSS) 2204 were investigated. The proportion of the ferrite phase increased while the austenite phase decreased and the ferrite stabilizing elements diluted in the ferrite phase with the increase of annealing temperature. The critical pitting temperature (CPT) of specimens annealed at 1000℃ was higher than those annealed at 950℃, whereas further increasing the annealing temperature to 1200℃ decreased the CPT. The pitting initiation sites were observed in the austenite phase, at the boundary of ferrite/austenite phase and inside the ferrite phase for specimens annealed at 950, 1000℃ and exceeding 1 100℃, respectively. The evolution trend of the CPT and the pit initiation site were analyzed by the pitting resistance equivalent number.展开更多
The effect of solution annealing on the microstructure and mechanical properties of a Ni-Cr-W-Fe alloy developed for advanced 700?C ultra-supercritical power plants was investigated. Test samples in this study were s...The effect of solution annealing on the microstructure and mechanical properties of a Ni-Cr-W-Fe alloy developed for advanced 700?C ultra-supercritical power plants was investigated. Test samples in this study were subjected to different solution treatments and the same aging treatment(at 760?C for 1 h).When solution annealing temperature was elevated from 1020?C to 1150?C, the stress-rupture life at750?C/320 MPa was increased from 60 h to 300 h, the stress-rupture elongation was enhanced from12% to 17%, and the elongation of the tensile at 750?C was improved from 11% to 24%. All tensile and stress-rupture samples displayed an intergranular dimple mixed fracture. Intergranular micro-cracks had a great relationship with the morphology of grain boundary carbides. Most carbides retained the morphology of globular shape and continuous thin plate. After tensile and stress-rupture tests, a few carbides were converted into lamellar. The results showed that intergranular micro-cracks were easier to form at continuous thin plate carbides than at globular shape carbides. Lamellar carbides hardly caused the nucleation of micro-cracks. Besides, grain boundaries sliding and elements diffusion during stressrupture tests led to the formation of precipitate free zones, which accelerated the extension of microcracks and influenced the stress-rupture life.展开更多
Micro-alloying effects of yttrium on the recrystallization behavior of an alumina-forming austenitic(AFA)stainless steel were investigated.It was found that the grain growth kinetics of the steels doped with differe...Micro-alloying effects of yttrium on the recrystallization behavior of an alumina-forming austenitic(AFA)stainless steel were investigated.It was found that the grain growth kinetics of the steels doped with different amounts of yttrium(i.e.,0,0.05 and 0.10mass% Y)could be described by an Arrhenius type empirical equation.Added Y could interact with carbon and influence the morphology of carbides both inside grains and on the grain boundaries,thus altering the grain boundary mobility and grain growth.The steel doped with 0.05mass% yttrium showed the highest activation energy of grain growth and the most retarded recrystallization behavior,which mainly resulted from the high density of fine carbides both inside grains and on the grain boundaries.However,excess addition of0.10mass% Y induced coarsening and then lowered density of carbides,which alleviated the yttrium effects.The results also manifest that micro-alloying of rare-earth elements such as yttrium is an effective way for controlling grain growth behavior during recrystallization of AFA steels,which may have great implications on engineering applications.展开更多
基金Item Sponsored by National Natural Science Foundation of China(51131008,51371053)National Key Technology Research and Development Program of China(2012BAE04B00)Doctoral Fund of the Ministry of Education of China(20120071110013)
文摘The effect of solution annealing temperature ranging from 950 to 1 200 ℃ on the microstructure and corrosion performance of duplex stainless steel (DSS) 2204 were investigated. The proportion of the ferrite phase increased while the austenite phase decreased and the ferrite stabilizing elements diluted in the ferrite phase with the increase of annealing temperature. The critical pitting temperature (CPT) of specimens annealed at 1000℃ was higher than those annealed at 950℃, whereas further increasing the annealing temperature to 1200℃ decreased the CPT. The pitting initiation sites were observed in the austenite phase, at the boundary of ferrite/austenite phase and inside the ferrite phase for specimens annealed at 950, 1000℃ and exceeding 1 100℃, respectively. The evolution trend of the CPT and the pit initiation site were analyzed by the pitting resistance equivalent number.
文摘The effect of solution annealing on the microstructure and mechanical properties of a Ni-Cr-W-Fe alloy developed for advanced 700?C ultra-supercritical power plants was investigated. Test samples in this study were subjected to different solution treatments and the same aging treatment(at 760?C for 1 h).When solution annealing temperature was elevated from 1020?C to 1150?C, the stress-rupture life at750?C/320 MPa was increased from 60 h to 300 h, the stress-rupture elongation was enhanced from12% to 17%, and the elongation of the tensile at 750?C was improved from 11% to 24%. All tensile and stress-rupture samples displayed an intergranular dimple mixed fracture. Intergranular micro-cracks had a great relationship with the morphology of grain boundary carbides. Most carbides retained the morphology of globular shape and continuous thin plate. After tensile and stress-rupture tests, a few carbides were converted into lamellar. The results showed that intergranular micro-cracks were easier to form at continuous thin plate carbides than at globular shape carbides. Lamellar carbides hardly caused the nucleation of micro-cracks. Besides, grain boundaries sliding and elements diffusion during stressrupture tests led to the formation of precipitate free zones, which accelerated the extension of microcracks and influenced the stress-rupture life.
基金Item Sponsored by National Natural Science Foundation of China(51531001,51422101,51371003,51271212)111 Project(B07003)+3 种基金International Science and Technology Cooperation Program of China(2015DFG52600)Program for Changjiang Scholars and Innovative Research Team in University of China(IRT_14R05)Fundamental Research Fund for the Central Universities of China(FRF-TP-15-004C1,FRF-TP-14-009C1)Top-Notch Young Talents Program of China
文摘Micro-alloying effects of yttrium on the recrystallization behavior of an alumina-forming austenitic(AFA)stainless steel were investigated.It was found that the grain growth kinetics of the steels doped with different amounts of yttrium(i.e.,0,0.05 and 0.10mass% Y)could be described by an Arrhenius type empirical equation.Added Y could interact with carbon and influence the morphology of carbides both inside grains and on the grain boundaries,thus altering the grain boundary mobility and grain growth.The steel doped with 0.05mass% yttrium showed the highest activation energy of grain growth and the most retarded recrystallization behavior,which mainly resulted from the high density of fine carbides both inside grains and on the grain boundaries.However,excess addition of0.10mass% Y induced coarsening and then lowered density of carbides,which alleviated the yttrium effects.The results also manifest that micro-alloying of rare-earth elements such as yttrium is an effective way for controlling grain growth behavior during recrystallization of AFA steels,which may have great implications on engineering applications.