An innovative approach was introduced for the development of a AA6063 recrystallization model.This method incorporated a regression-based technique for the determination of material constants and introduced novel equa...An innovative approach was introduced for the development of a AA6063 recrystallization model.This method incorporated a regression-based technique for the determination of material constants and introduced novel equations for assessing the grain size evolution.Calibration and validation of this methodology involved a combination of experimentally acquired microstructural data from the extrusion of three different AA6063 profiles and results from the simulation using the Qform Extrusion UK finite element code.The outcomes proved the agreement between experimental findings and numerical prediction of the microstructural evolution.The trend of the grain size variation based on different process parameters was accurately simulated,both after dynamic and static recrystallization,with an error of less than 25% in almost the whole sampling computations.展开更多
The hot deformation and dynamic recrystallization(DRX)behaviors of 7055 aluminum alloy were studied at temperatures of 390−470℃ and strain rates of 0.01−1 s^(−1).A low DRX fraction between 1% and 13% was observed by ...The hot deformation and dynamic recrystallization(DRX)behaviors of 7055 aluminum alloy were studied at temperatures of 390−470℃ and strain rates of 0.01−1 s^(−1).A low DRX fraction between 1% and 13% was observed by using EBSD technique.A modified JMAK-type DRX model was proposed for such low DRX fraction problems.The model was used together with commercial FEM software DEFORM-3D to simulate the hot compression of 7055 aluminum alloy.There was a good agreement between experimental and predicted DRX fractions and grain size with an average absolute relative error(AARE)of 13.7% and 6.3%,respectively.In order to further verify the validity of the proposed model,the model was also used to simulate DRX in industrial hot rolling of 7055 aluminum alloys.The results showed that the distribution of DRX fraction was inhomogeneous,and agreed with experimental observations.展开更多
Isothermal compression tests were conducted to predict the hot deformational flow stress behaviour of 2024AI-T3 alloy with respect to a wide range of strain rates （0.001-100 s l）, strains （0.1-0.5） and temperatur...Isothermal compression tests were conducted to predict the hot deformational flow stress behaviour of 2024AI-T3 alloy with respect to a wide range of strain rates （0.001-100 s l）, strains （0.1-0.5） and temperatures （573-773 K）. The prediction capabilities of various constitutive models for 2024A1 alloys and a recently developed constitutive model were evaluated using statistical parameters such as the average absolute relative error （AARE） and the correlation coefficient （R）. Models recorded the lowest AARE （4.6%） and the highest correlation coefficient （R=0.99） were developed compared with the other models. Hence, this model can track the deformational behaviour of 2027Al-T3 alloy more accurately compared with other models throughout the entire processing domain investigated.展开更多
The use of a constrained groove pressing(CGP) method to plastically deform AA6063 aluminum alloy led to the improved surface properties. It was found that hardness magnitude is dramatically improved and its uniformity...The use of a constrained groove pressing(CGP) method to plastically deform AA6063 aluminum alloy led to the improved surface properties. It was found that hardness magnitude is dramatically improved and its uniformity is considerably decreased after the first pass, while subsequent passes result in better hardness behavior for the processed material. Also, the elongated grains formed in the first pass of the CGP are gradually converted to the equiaxed counterparts by adding pass numbers. Eventually, higher corrosion resistance of the sample by imposing the CGP process is related to the quick formation of passivation film and the change in the morphology of the second phase and precipitates which hinder their electrochemical reactions and decrease the potential localized attack sites.展开更多
The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morpholo...The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morphology was observed by means of electron backscatter diffraction(EBSD)technology.The results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain rate.In contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain rates.The microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix zones.The grain size in the welding zone was smaller than that in the matrix zone due to lower DRX fraction.The decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.展开更多
文摘An innovative approach was introduced for the development of a AA6063 recrystallization model.This method incorporated a regression-based technique for the determination of material constants and introduced novel equations for assessing the grain size evolution.Calibration and validation of this methodology involved a combination of experimentally acquired microstructural data from the extrusion of three different AA6063 profiles and results from the simulation using the Qform Extrusion UK finite element code.The outcomes proved the agreement between experimental findings and numerical prediction of the microstructural evolution.The trend of the grain size variation based on different process parameters was accurately simulated,both after dynamic and static recrystallization,with an error of less than 25% in almost the whole sampling computations.
基金the financial supports from the National Key Research and Development Program of China(No.2016YFB-0300901)the National Natural Science Foundation of China(No.51871033)+1 种基金the Chongqing Research Program of Basic Research and Frontier Technology,China(No.cstc2017jcyjAX0245)the Venture&Innovation Support Program for Chongqing Overseas Returnees,China(No.cx2018002).
文摘The hot deformation and dynamic recrystallization(DRX)behaviors of 7055 aluminum alloy were studied at temperatures of 390−470℃ and strain rates of 0.01−1 s^(−1).A low DRX fraction between 1% and 13% was observed by using EBSD technique.A modified JMAK-type DRX model was proposed for such low DRX fraction problems.The model was used together with commercial FEM software DEFORM-3D to simulate the hot compression of 7055 aluminum alloy.There was a good agreement between experimental and predicted DRX fractions and grain size with an average absolute relative error(AARE)of 13.7% and 6.3%,respectively.In order to further verify the validity of the proposed model,the model was also used to simulate DRX in industrial hot rolling of 7055 aluminum alloys.The results showed that the distribution of DRX fraction was inhomogeneous,and agreed with experimental observations.
文摘Isothermal compression tests were conducted to predict the hot deformational flow stress behaviour of 2024AI-T3 alloy with respect to a wide range of strain rates （0.001-100 s l）, strains （0.1-0.5） and temperatures （573-773 K）. The prediction capabilities of various constitutive models for 2024A1 alloys and a recently developed constitutive model were evaluated using statistical parameters such as the average absolute relative error （AARE） and the correlation coefficient （R）. Models recorded the lowest AARE （4.6%） and the highest correlation coefficient （R=0.99） were developed compared with the other models. Hence, this model can track the deformational behaviour of 2027Al-T3 alloy more accurately compared with other models throughout the entire processing domain investigated.
基金funded by“Quality Engineering Project of Anhui Province of China in 2016”entitled mold design and manufacturing experimental training center(2016sxzx050)。
文摘The use of a constrained groove pressing(CGP) method to plastically deform AA6063 aluminum alloy led to the improved surface properties. It was found that hardness magnitude is dramatically improved and its uniformity is considerably decreased after the first pass, while subsequent passes result in better hardness behavior for the processed material. Also, the elongated grains formed in the first pass of the CGP are gradually converted to the equiaxed counterparts by adding pass numbers. Eventually, higher corrosion resistance of the sample by imposing the CGP process is related to the quick formation of passivation film and the change in the morphology of the second phase and precipitates which hinder their electrochemical reactions and decrease the potential localized attack sites.
基金Project(U1664252)supported by the National Natural Science Foundation of China
文摘The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morphology was observed by means of electron backscatter diffraction(EBSD)technology.The results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain rate.In contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain rates.The microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix zones.The grain size in the welding zone was smaller than that in the matrix zone due to lower DRX fraction.The decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.
