The comparative experiments of age forming and artificial aging of 2A12 aluminum alloy were carried out. The effect of the age forming on the microstructure and mechanical properties was investigated. The results demo...The comparative experiments of age forming and artificial aging of 2A12 aluminum alloy were carried out. The effect of the age forming on the microstructure and mechanical properties was investigated. The results demonstrate that the grains are further squashed and elongated compared with artificial aging due to the existence of the applied stress during the age forming. Meanwhile, the precipitated phases change from circle shape with random orientation of age forming to long strip shape with uniform orientation of artificial aging. The dislocation configuration in samples changes from ring dislocation or helical dislocation of the artificial aging to long and straight dislocation of the age forming. Otherwise, age forming slightly reduces the tensile properties and fracture toughness of the alloy and enhances its fatigue crack growth rate.展开更多
A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum allo...A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum alloy sheet was calculated based on the two flow stress—strain relations using Yld2000-2d yield function. By comparing the theoretical and experimental results, it is found that the calculated FLD-strain based on the modified Swift flow stress—strain relation can reasonably describe the experimental results. However, though the common Voce flow stress—strain relation can describe the deformation behavior during homogenous deformation phase accurately, the FLD-strain calculated based on it is obviously lower than the experimental result. It is concluded that the higher the hardening rate of sheet metal is, the higher the forming limit is. A method for determining the reasonable flow stress—strain relation is recommended for describing the material behavior during inhomogenous phase and the forming limit of sheet metal.展开更多
The systematic experimental studies were performed on the hydrate formation kinetics and gas-hydrate equilibrium for a simulated catalytic cracking gas in the water-in-oil emulsion. The effect of temperature, pressure...The systematic experimental studies were performed on the hydrate formation kinetics and gas-hydrate equilibrium for a simulated catalytic cracking gas in the water-in-oil emulsion. The effect of temperature, pressure and initial gas-liquid ratio on the hydrate formation was studied, respectively. The data were obtained at pressures ranging from 3.5 to 5 MPa and temperatur.es from 274.15 to 277.15 K. The results showed that hydrogen and methane can be separated Irom the （~2＋ ti＇action by tOrming hydrate at around 273.15 K which is much higher temperature than that of the cryogenic separation method, and the hydrate formation rate can be enhanced in the wa- ter-in-oil emulsion compared to pure water. The experiments provided the basic data for designing the industrial process, and setting the suitable operational conditions. The measured data ot gas-hydrate equilibria were compared with the predictions by using the Chen-Guo hydrate thermodynamic model.展开更多
基金Project (NCET-10-0278) supported by the Program for New Century Excellent Talents in University, ChinaProject (20102024) supported by the Natural Science Foundation of Liaoning Province, China
文摘The comparative experiments of age forming and artificial aging of 2A12 aluminum alloy were carried out. The effect of the age forming on the microstructure and mechanical properties was investigated. The results demonstrate that the grains are further squashed and elongated compared with artificial aging due to the existence of the applied stress during the age forming. Meanwhile, the precipitated phases change from circle shape with random orientation of age forming to long strip shape with uniform orientation of artificial aging. The dislocation configuration in samples changes from ring dislocation or helical dislocation of the artificial aging to long and straight dislocation of the age forming. Otherwise, age forming slightly reduces the tensile properties and fracture toughness of the alloy and enhances its fatigue crack growth rate.
基金Project(51005010)supported by the National Natural Science Foundation of China
文摘A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum alloy sheet was calculated based on the two flow stress—strain relations using Yld2000-2d yield function. By comparing the theoretical and experimental results, it is found that the calculated FLD-strain based on the modified Swift flow stress—strain relation can reasonably describe the experimental results. However, though the common Voce flow stress—strain relation can describe the deformation behavior during homogenous deformation phase accurately, the FLD-strain calculated based on it is obviously lower than the experimental result. It is concluded that the higher the hardening rate of sheet metal is, the higher the forming limit is. A method for determining the reasonable flow stress—strain relation is recommended for describing the material behavior during inhomogenous phase and the forming limit of sheet metal.
基金Supported by the National iqatural Science Foundation of China （20925623, U1162205）.
文摘The systematic experimental studies were performed on the hydrate formation kinetics and gas-hydrate equilibrium for a simulated catalytic cracking gas in the water-in-oil emulsion. The effect of temperature, pressure and initial gas-liquid ratio on the hydrate formation was studied, respectively. The data were obtained at pressures ranging from 3.5 to 5 MPa and temperatur.es from 274.15 to 277.15 K. The results showed that hydrogen and methane can be separated Irom the （~2＋ ti＇action by tOrming hydrate at around 273.15 K which is much higher temperature than that of the cryogenic separation method, and the hydrate formation rate can be enhanced in the wa- ter-in-oil emulsion compared to pure water. The experiments provided the basic data for designing the industrial process, and setting the suitable operational conditions. The measured data ot gas-hydrate equilibria were compared with the predictions by using the Chen-Guo hydrate thermodynamic model.
