Microstructures and mechanical properties of the 25Mn twinning induced plasticity （TWIP） steel at different annealing temperatures were investigated. The results indicated that when the annealing temperature was 100...Microstructures and mechanical properties of the 25Mn twinning induced plasticity （TWIP） steel at different annealing temperatures were investigated. The results indicated that when the annealing temperature was 1000℃, the 25Mn steel showed excellent comprehensive mechanical properties, the tensile strength was about 640 MPa, the yield strength was higher than 255 MPa, and the elongation was above 82%. The microstructure was analyzed by optical microscopy （OM）, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. Before deformation the microstructure was composed of austenitic matrix and annealing twins at room temperature; at the same time, a significant amount of annealing twins and stacking faults were observed by TEM. Mechanical twins played a dominant role in deformation and as a result the mechanical properties were found to be excellent.展开更多
Nanocrystalline nickel coatings with grain size of 50 nm were annealed in vacuum at 200 ℃ and 400 ℃ for 10 min, Their microstructures were investigated by transmission electron microscopy （TEM）. And their corrosio...Nanocrystalline nickel coatings with grain size of 50 nm were annealed in vacuum at 200 ℃ and 400 ℃ for 10 min, Their microstructures were investigated by transmission electron microscopy （TEM）. And their corrosion behaviors were studied by means of polarization and electrochemical impedance spectroscopy （EIS）, The results showed that their grain size grew up to about 60 nm （200 ℃） and 500 nm （400 ℃）, respectively, The specimen annealed at 200 ℃ possessed higher density of twins in compared with the counterparts of as-deposited and annealed at 400 ℃, The normal grain size effect on the corrosion behavior was not observed, However, it was found that the corrosion resistance of the coating linearly changed with the density of twins.展开更多
Dynamic recrystallization （DRX） mechanisms of a nickel-based corrosion-resistant alloy, G3, were investigated by hot compression tests with temperatures from 1050 to 1200 ℃ and strain rates from 0.1 to 5.0 s-1. Def...Dynamic recrystallization （DRX） mechanisms of a nickel-based corrosion-resistant alloy, G3, were investigated by hot compression tests with temperatures from 1050 to 1200 ℃ and strain rates from 0.1 to 5.0 s-1. Deformation microstructure was observed at the strain from 0.05 to 0.75 by electron backscatter diffraction （EBSD） and transmission electron microscope （TEM）. Work hardening rate curves were calculated to analyze the effect of deformation parameters on the nucleation process. Results indicate that strain-induced grain boundary migration is the principal mechanism of DRX. Large annealing twins promote nucleation by accumulating dis- locations and fragmenting into cell blocks. Continuous dynamic recrystallization is also detected to be an effective supplement mechanism, especially at low temperature and high strain rate.展开更多
基金the National Natural Science Foundation of China (No.50575022)the Specialized Research Foundation for the Doctoral Program of Higher Education of China (No.20040008024)the National High-Tech Research and Development Program of China (No.2008AA03E502)
文摘Microstructures and mechanical properties of the 25Mn twinning induced plasticity （TWIP） steel at different annealing temperatures were investigated. The results indicated that when the annealing temperature was 1000℃, the 25Mn steel showed excellent comprehensive mechanical properties, the tensile strength was about 640 MPa, the yield strength was higher than 255 MPa, and the elongation was above 82%. The microstructure was analyzed by optical microscopy （OM）, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. Before deformation the microstructure was composed of austenitic matrix and annealing twins at room temperature; at the same time, a significant amount of annealing twins and stacking faults were observed by TEM. Mechanical twins played a dominant role in deformation and as a result the mechanical properties were found to be excellent.
基金State Key Laboratory of Mechanical Transmission for Advanced Equipment Project (SKLMT-MSKFKT-202219)Natural Science Foundation of Jiangsu Province (BK20220548)+1 种基金Open Research Fund from the State Key Lab of Advanced Metals and Materials,University of Science and Technology Beijing (2022-Z21)National Natural Science Foundation of China (52005223)。
基金the financial support from the National Basic Research Program of China(No.2014CB643301)the National Natural Science Foundation of China(Nos.50971050 and 51001036)+3 种基金the Program for New Century Excellent Talents in University(No.NCET-11-0575)the Ministry of Science and Technology of the People’s Republic of China(No.2012FY113000)the Key Laboratory of Superlight Materials and Surface Technology(Harbin Engineering University,No.HEUCF20151011)Ministry of Education(No.HEUCF20151011)
文摘Nanocrystalline nickel coatings with grain size of 50 nm were annealed in vacuum at 200 ℃ and 400 ℃ for 10 min, Their microstructures were investigated by transmission electron microscopy （TEM）. And their corrosion behaviors were studied by means of polarization and electrochemical impedance spectroscopy （EIS）, The results showed that their grain size grew up to about 60 nm （200 ℃） and 500 nm （400 ℃）, respectively, The specimen annealed at 200 ℃ possessed higher density of twins in compared with the counterparts of as-deposited and annealed at 400 ℃, The normal grain size effect on the corrosion behavior was not observed, However, it was found that the corrosion resistance of the coating linearly changed with the density of twins.
基金financially supported by the National Natural Science Foundation of China(No.51301085)the Doctoral Scientific Research Foundation of Nanjing Institute of Technology(No.YKJ201305)
文摘Dynamic recrystallization （DRX） mechanisms of a nickel-based corrosion-resistant alloy, G3, were investigated by hot compression tests with temperatures from 1050 to 1200 ℃ and strain rates from 0.1 to 5.0 s-1. Deformation microstructure was observed at the strain from 0.05 to 0.75 by electron backscatter diffraction （EBSD） and transmission electron microscope （TEM）. Work hardening rate curves were calculated to analyze the effect of deformation parameters on the nucleation process. Results indicate that strain-induced grain boundary migration is the principal mechanism of DRX. Large annealing twins promote nucleation by accumulating dis- locations and fragmenting into cell blocks. Continuous dynamic recrystallization is also detected to be an effective supplement mechanism, especially at low temperature and high strain rate.
