Thermal deformation characteristics of Fe-Cr-Ni-based alloys for nuclear power plants were investigated using a Gleeble3500 thermal simulation tester.The microstructure evolution law of alloy heat deformation was inve...Thermal deformation characteristics of Fe-Cr-Ni-based alloys for nuclear power plants were investigated using a Gleeble3500 thermal simulation tester.The microstructure evolution law of alloy heat deformation was investigated using the electron backscatter diffraction(EBSD)technique.Results demonstrate that the flow stress curves show typical dynamic recrystallization(DRX)characteristics.According to EBSD analysis,the nucleation and growth of DRX grains are mainly at grain boundaries.The complete DRX occurs at 1100℃/0.01 s^(−1) condition,and the grains are refined.The main DRX nucleation mechanism of the alloy is the grain boundary bowing nucleation.Therefore,the softening mechanism of Fe-Cr-Ni-based alloys for nuclear power plants is the combination of dynamic recovery and DRX.The Arrhenius constitutive model with strain compensation is developed.The correlation coefficient between the predicted and experimental values is 0.9947.The reliable mathematical model of critical stress(strain)and Z parameter is obtained.The critical stress(strain)of DRX increases as the temperature decreases or the strain rate increases.The DRX kinetic model is established by the Avrami model,and a typical S-type curve is obtained.As the strain rate decreases and the temperature increases,the volume fraction of DRX increases.展开更多
The failure of mechanical components is mainly caused by three key mechanisms:wear,corrosion,and fatigue.Among these failure modes,wear of mechanical components notably increases energy consumption and leads to substa...The failure of mechanical components is mainly caused by three key mechanisms:wear,corrosion,and fatigue.Among these failure modes,wear of mechanical components notably increases energy consumption and leads to substantial economic losses.Fe-Cr-C-B-Ti-Y wear-resistant cladding metals were prepared by the plasma cladding method.The wear performance of the cladding metals was analyzed using an MLS-23 rubber wheel wet sand wear tester.X-ray diffraction,scanning electron microscope,electron backscatter diffraction,and transmission electron microscope were employed to investigate the phase composition and microstructure of the cladding metals,followed by a discussion of their strengthening and wear mechanisms.The results indicate that the microstructure of Fe-Cr-C-B-Ti-Y cladding metals is composed of austeniteγ-Fe,M_(23)(C,B)_(6)eutectic carbide,and TiC hard phase.As the Y_(2)O_(3)content increases,the hardness and wear resistance of the cladding metal show a trend of first increasing and then decreasing.When the Y_(2)O_(3)content is 0.4wt%,the precipitation of TiC hard phase and M_(23)(C,B)_(6)-type eutectic carbides reaches maximum,and the grain size is the finest.The cladding metal exhibits optimal formability,featuring the smallest wetting angle of 52.2°.Under this condition,the Rockwell hardness value of the cladding metal is 89.7 HRC,and the wear mass loss is 0.27 g.The dominant wear mechanism of cladding metals is abrasive wear,and the material removal process involves micro-cutting and plowing.展开更多
The reduction behaviors and characteristics of products of the Fe-Cr-O system （FeCr2O4 and Fe2O3＋Cr2O3） and Fe-Cr-Ni-O system （Fe2O3＋Cr2O3＋NiO） under various conditions were studied. The results show that more ...The reduction behaviors and characteristics of products of the Fe-Cr-O system （FeCr2O4 and Fe2O3＋Cr2O3） and Fe-Cr-Ni-O system （Fe2O3＋Cr2O3＋NiO） under various conditions were studied. The results show that more Fe-Cr or Fe-Cr-Ni solution and less residual carbon content were obtained at higher temperatures and lower initial molar ratio of C to O （nC：nO）. The degree of reduction was highly dependent on both time and temperature, and the residual carbon content greatly increased with increasing nC：nO at each temperature. The products generated during the carbothermic reduction of the Fe-Cr-O system were examined using X-ray diffraction （XRD）. A scanning electron microscope （SEM） coupled with energy dispersive spectrometer was used to observe the microstructure and the distribution of elements in the various phases of the final reduction products of the Fe-Cr-O and Fe-Cr-Ni-O.展开更多
基金Key Projects of Hubei Provincial Department of Education(D20201206)Industrial Technology Basic Public Service Platform in 2022(2022-232-223)National Natural Science Foundation of China(51531009)。
文摘Thermal deformation characteristics of Fe-Cr-Ni-based alloys for nuclear power plants were investigated using a Gleeble3500 thermal simulation tester.The microstructure evolution law of alloy heat deformation was investigated using the electron backscatter diffraction(EBSD)technique.Results demonstrate that the flow stress curves show typical dynamic recrystallization(DRX)characteristics.According to EBSD analysis,the nucleation and growth of DRX grains are mainly at grain boundaries.The complete DRX occurs at 1100℃/0.01 s^(−1) condition,and the grains are refined.The main DRX nucleation mechanism of the alloy is the grain boundary bowing nucleation.Therefore,the softening mechanism of Fe-Cr-Ni-based alloys for nuclear power plants is the combination of dynamic recovery and DRX.The Arrhenius constitutive model with strain compensation is developed.The correlation coefficient between the predicted and experimental values is 0.9947.The reliable mathematical model of critical stress(strain)and Z parameter is obtained.The critical stress(strain)of DRX increases as the temperature decreases or the strain rate increases.The DRX kinetic model is established by the Avrami model,and a typical S-type curve is obtained.As the strain rate decreases and the temperature increases,the volume fraction of DRX increases.
文摘The failure of mechanical components is mainly caused by three key mechanisms:wear,corrosion,and fatigue.Among these failure modes,wear of mechanical components notably increases energy consumption and leads to substantial economic losses.Fe-Cr-C-B-Ti-Y wear-resistant cladding metals were prepared by the plasma cladding method.The wear performance of the cladding metals was analyzed using an MLS-23 rubber wheel wet sand wear tester.X-ray diffraction,scanning electron microscope,electron backscatter diffraction,and transmission electron microscope were employed to investigate the phase composition and microstructure of the cladding metals,followed by a discussion of their strengthening and wear mechanisms.The results indicate that the microstructure of Fe-Cr-C-B-Ti-Y cladding metals is composed of austeniteγ-Fe,M_(23)(C,B)_(6)eutectic carbide,and TiC hard phase.As the Y_(2)O_(3)content increases,the hardness and wear resistance of the cladding metal show a trend of first increasing and then decreasing.When the Y_(2)O_(3)content is 0.4wt%,the precipitation of TiC hard phase and M_(23)(C,B)_(6)-type eutectic carbides reaches maximum,and the grain size is the finest.The cladding metal exhibits optimal formability,featuring the smallest wetting angle of 52.2°.Under this condition,the Rockwell hardness value of the cladding metal is 89.7 HRC,and the wear mass loss is 0.27 g.The dominant wear mechanism of cladding metals is abrasive wear,and the material removal process involves micro-cutting and plowing.
基金Project (51074025) supported by the National Natural Science Foundation of ChinaProject (FRF-SD-12-009A) supported by the Fundamental Research Funds for the Central Universities,China
文摘The reduction behaviors and characteristics of products of the Fe-Cr-O system （FeCr2O4 and Fe2O3＋Cr2O3） and Fe-Cr-Ni-O system （Fe2O3＋Cr2O3＋NiO） under various conditions were studied. The results show that more Fe-Cr or Fe-Cr-Ni solution and less residual carbon content were obtained at higher temperatures and lower initial molar ratio of C to O （nC：nO）. The degree of reduction was highly dependent on both time and temperature, and the residual carbon content greatly increased with increasing nC：nO at each temperature. The products generated during the carbothermic reduction of the Fe-Cr-O system were examined using X-ray diffraction （XRD）. A scanning electron microscope （SEM） coupled with energy dispersive spectrometer was used to observe the microstructure and the distribution of elements in the various phases of the final reduction products of the Fe-Cr-O and Fe-Cr-Ni-O.
