The effect of bainite transformation and microstructure on the mechanical properties in 0.3%C bainitic steel was investigated via the heat treatment process of quenching at higher initial temperature and partitioning ...The effect of bainite transformation and microstructure on the mechanical properties in 0.3%C bainitic steel was investigated via the heat treatment process of quenching at higher initial temperature and partitioning below martensite-start temperature. The results show that bainite transformation takes place with the partitioning time increasing during partitioning below martensite-start temperature. The microstructure of samples treated by this two-step quenching and partitioning process consists of lath bainite, lath martensite and retained austenite. This kind of multiphase microstructure exhibits better strength of 1420 MPa, ductility of 21.8 % and the product of strength and elongation of 30.8 GPa%. Furthermore, the excellent impact toughness of 103 J is exhibited by partitioning at 280 ℃ for 3 h. In addition, the coalescence of bainite platelets was found in the sample treated by partitioning for 8 h, leading to the deterioration of toughness.展开更多
Binary bright Ni-Co alloy films were electro- deposited on titanium in the chloride-sulfate electrolytes. The influences of Co2＋ concentration, current density, and temperature on the Ni-Co alloy films electrodeposit...Binary bright Ni-Co alloy films were electro- deposited on titanium in the chloride-sulfate electrolytes. The influences of Co2＋ concentration, current density, and temperature on the Ni-Co alloy films electrodeposition were investigated. The films were analyzed by scanning electron microscope （SEM）, energy dispersive spectros- copy （EDS）, and X-ray diffraction （XRD）. Cathodic polarization for Ni-Co codeposition was performed on Ti working electrodes. With the increase of Co2＋ concentra- tion, the Ni content in the films decreases and the current efficiency increases slightly. The Ni content increases with the increase of temperature, while it decreases with the increase of current density to a minimum and then increases. The cathodic reduction peak potential is mea- sured to be -1.34 V. Anomalous deposition is found to occur in the Ni-Co codeposition. The SEM of Ni-Co alloy films shows that hydroxide particles are not present on the surface and fine grain, compact, smooth, and bright Ni--Co alloy films are obtained. The XRD result indicates that the deposited Ni-Co alloy film is Ni-solid solution with a face- centered cubic in structure.展开更多
文摘The effect of bainite transformation and microstructure on the mechanical properties in 0.3%C bainitic steel was investigated via the heat treatment process of quenching at higher initial temperature and partitioning below martensite-start temperature. The results show that bainite transformation takes place with the partitioning time increasing during partitioning below martensite-start temperature. The microstructure of samples treated by this two-step quenching and partitioning process consists of lath bainite, lath martensite and retained austenite. This kind of multiphase microstructure exhibits better strength of 1420 MPa, ductility of 21.8 % and the product of strength and elongation of 30.8 GPa%. Furthermore, the excellent impact toughness of 103 J is exhibited by partitioning at 280 ℃ for 3 h. In addition, the coalescence of bainite platelets was found in the sample treated by partitioning for 8 h, leading to the deterioration of toughness.
基金financially supported by the National Natural Science Foundation of China(No.21273190)the Opening Fund from Hunan Province Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications(No.2012XGJSYB01)
文摘Binary bright Ni-Co alloy films were electro- deposited on titanium in the chloride-sulfate electrolytes. The influences of Co2＋ concentration, current density, and temperature on the Ni-Co alloy films electrodeposition were investigated. The films were analyzed by scanning electron microscope （SEM）, energy dispersive spectros- copy （EDS）, and X-ray diffraction （XRD）. Cathodic polarization for Ni-Co codeposition was performed on Ti working electrodes. With the increase of Co2＋ concentra- tion, the Ni content in the films decreases and the current efficiency increases slightly. The Ni content increases with the increase of temperature, while it decreases with the increase of current density to a minimum and then increases. The cathodic reduction peak potential is mea- sured to be -1.34 V. Anomalous deposition is found to occur in the Ni-Co codeposition. The SEM of Ni-Co alloy films shows that hydroxide particles are not present on the surface and fine grain, compact, smooth, and bright Ni--Co alloy films are obtained. The XRD result indicates that the deposited Ni-Co alloy film is Ni-solid solution with a face- centered cubic in structure.
