Hot tensile tests were performed on Hastelloy C-276 alloy in the temperature range of 850−1150℃ and strain rate range of 0.01−10 s^(−1) to reveal its fracture characteristics and critical fracture failure conditions ...Hot tensile tests were performed on Hastelloy C-276 alloy in the temperature range of 850−1150℃ and strain rate range of 0.01−10 s^(−1) to reveal its fracture characteristics and critical fracture failure conditions during high temperature deformation process.Short-term aging treatments were also conducted to analyze the effects of precipitation on the fracture behaviors in conjunction with the experimental results obtained from the hot tensile tests.It was observed that the main precipitates in Hastelloy C-276 alloy under hot tensile deformation and short-term aging treatment were identified as M_(6)C carbides,around which the microscopic voids nucleate when the external forces were applied.Considering the effects of deformation temperature and strain rate,two failure criteria based on Zener-Hollomon parameter were developed to describe the fracture behaviors of Hastelloy C-276 alloy deforming at elevated temperatures.Finite element method(FEM)coupling with the proposed failure criteria was used to examine the validity by comparing the predicted values with the experimental data,and the comparison results indicate that the established failure criteria were capable of predicting the fracture behaviors of Hastelloy C-276 alloy in hot deformation process.展开更多
The influence of different ageing processes on the microstructure, corrosion behaviors and mechanical properties of extruded Al-5.6Zn-1.6Mg-0.05Zr(wt.%) alloy was studied in this work. The changes of morphology, size ...The influence of different ageing processes on the microstructure, corrosion behaviors and mechanical properties of extruded Al-5.6Zn-1.6Mg-0.05Zr(wt.%) alloy was studied in this work. The changes of morphology, size and distribution of MgZn_(2)precipitate with ageing temperature and time were revealed by optical and electron microscopy. Intergranular corrosion(IGC) and exfoliation corrosion(EXCO) tests were carried out to assess the changes in corrosion susceptibility of the tempered alloy, and some white spots on the surface of the sample aged for longer time were found to be precursors of pits. Electrochemical cyclic polarization test depicted the corrosion behavior under different tempers. Ageing influences on the mechanical behaviors of the alloy were revealed by evaluating its microhardness and tensile strength. The microscopic features of the strengthening phases determined by the ageing procedure directly affect the corrosion resistance and mechanical properties of the alloy.展开更多
The effects of solution treatment temperature and holding time on the microstructure and mechanical properties of extruded Al-6.02 wt.%Zn-1.94 wt.%Mg alloy were investigated by differential scanning calorimetry(DSC),o...The effects of solution treatment temperature and holding time on the microstructure and mechanical properties of extruded Al-6.02 wt.%Zn-1.94 wt.%Mg alloy were investigated by differential scanning calorimetry(DSC),optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD), and tensile test. The results showed that the optimum solution treatment process for the alloy was 470 ℃, 2 h. The tensile strength, yield strength,and elongation of the samples after the aging treatment at 120℃ for 24 h were 486 MPa, 431 MPa, and 14.8%,respectively. The alloy produced more copious recrystallization with the augment of solution temperature and the extension of holding time. While the second phase of η(MgZn_(2)), and T(AlZnMgCu) in the matrix was not fully re-dissolved under the treatment condition of lower temperature or shorter holding time. Interestingly, the Zr aggregation was observed in the samples treated at 510 ℃ for 2 h, which led to the growth of the second phase particles and the increase of their area fraction.展开更多
基金Project(52205433)supported by the National Natural Science Foundation of China。
文摘Hot tensile tests were performed on Hastelloy C-276 alloy in the temperature range of 850−1150℃ and strain rate range of 0.01−10 s^(−1) to reveal its fracture characteristics and critical fracture failure conditions during high temperature deformation process.Short-term aging treatments were also conducted to analyze the effects of precipitation on the fracture behaviors in conjunction with the experimental results obtained from the hot tensile tests.It was observed that the main precipitates in Hastelloy C-276 alloy under hot tensile deformation and short-term aging treatment were identified as M_(6)C carbides,around which the microscopic voids nucleate when the external forces were applied.Considering the effects of deformation temperature and strain rate,two failure criteria based on Zener-Hollomon parameter were developed to describe the fracture behaviors of Hastelloy C-276 alloy deforming at elevated temperatures.Finite element method(FEM)coupling with the proposed failure criteria was used to examine the validity by comparing the predicted values with the experimental data,and the comparison results indicate that the established failure criteria were capable of predicting the fracture behaviors of Hastelloy C-276 alloy in hot deformation process.
基金Project(2021zzts0152) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(U1837207) supported by the National Natural Science Foundation of China。
文摘The influence of different ageing processes on the microstructure, corrosion behaviors and mechanical properties of extruded Al-5.6Zn-1.6Mg-0.05Zr(wt.%) alloy was studied in this work. The changes of morphology, size and distribution of MgZn_(2)precipitate with ageing temperature and time were revealed by optical and electron microscopy. Intergranular corrosion(IGC) and exfoliation corrosion(EXCO) tests were carried out to assess the changes in corrosion susceptibility of the tempered alloy, and some white spots on the surface of the sample aged for longer time were found to be precursors of pits. Electrochemical cyclic polarization test depicted the corrosion behavior under different tempers. Ageing influences on the mechanical behaviors of the alloy were revealed by evaluating its microhardness and tensile strength. The microscopic features of the strengthening phases determined by the ageing procedure directly affect the corrosion resistance and mechanical properties of the alloy.
基金Project(U1837207) supported by the National Natural Science Foundation of China。
文摘The effects of solution treatment temperature and holding time on the microstructure and mechanical properties of extruded Al-6.02 wt.%Zn-1.94 wt.%Mg alloy were investigated by differential scanning calorimetry(DSC),optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD), and tensile test. The results showed that the optimum solution treatment process for the alloy was 470 ℃, 2 h. The tensile strength, yield strength,and elongation of the samples after the aging treatment at 120℃ for 24 h were 486 MPa, 431 MPa, and 14.8%,respectively. The alloy produced more copious recrystallization with the augment of solution temperature and the extension of holding time. While the second phase of η(MgZn_(2)), and T(AlZnMgCu) in the matrix was not fully re-dissolved under the treatment condition of lower temperature or shorter holding time. Interestingly, the Zr aggregation was observed in the samples treated at 510 ℃ for 2 h, which led to the growth of the second phase particles and the increase of their area fraction.
