Laser welding is a highly promising joining method for Al alloys.However,certain limitations such as elevated thermal input and keyhole instability are associated with its application in medium-thickness aluminium all...Laser welding is a highly promising joining method for Al alloys.However,certain limitations such as elevated thermal input and keyhole instability are associated with its application in medium-thickness aluminium alloy plates.To address these issues,circular oscillating laser welding combined with post-weld heat treatment was employed to improve the formation quality and mechanical properties of the welds.The effects of the frequency of circular oscillating laser on the forming quality,microstructure,and properties of the welds were analyzed.At an oscillation frequency of 200 Hz,the grain size in the weld zone was reduced compared to single laser welding,and the maximum tensile strength of the weld was observed to reach(264.96±1.33)MPa,representing approximately 61.19%of the base metal.Following the post-weld heat treatment of"solid solution and artificial aging",the grain boundary segregation was diminished.Nanoscale precipitated phases are present in the weld zone.Furthermore,the tensile strength was augmented to(386.35±5.65)MPa,representing approximately 89.23%of the strength of the base metal.The results of this study can provide a theoretical basis and technological reference for the circular oscillating laser welding of medium-thickness 2219-T 6 aluminium alloy plates.展开更多
The creep deformation and mechanical properties of 2219 aluminum alloy were experimentally investigated under both tension and compression at the temperature of 165℃for different time.The results indicated that the c...The creep deformation and mechanical properties of 2219 aluminum alloy were experimentally investigated under both tension and compression at the temperature of 165℃for different time.The results indicated that the creep deformation under tensile stress was greater than that under compressive stress.As the stress level increases,the compressive creep rate showed more significant increase.The yield strength after compressive stress creep-ageing was higher than that after stress-free ageing,with the lowest strength observed in the tensile-aged sample.Overall,the average phase length after compressive stress creep-ageing was larger than after tensile stress ageing.Under tensile stress,the number and size of precipitates at small angles to the stress direction were larger than those perpendicular to the stress direction.In contrast,under compressive stress,this relationship was reversed,and the preferential orientation of phases became more pronounced with ageing time.A unified,physics-based creep-ageing constitutive model,accounting for the orientation of precipitation,was developed for both tensile and compressive stress conditions.The predicted results were in good agreement with the experimental data.These findings,along with the developed model,provide a theoretical and simulation basis for precise creep-ageing forming of components under complex stresses.展开更多
The impacts of asymmetric rolling(ASR)and cold rolling(CR)on the creep-aging behavior of AA2219 alloys were revealed by creep deformation experiments,tensile tests,electron backscattered diffraction(EBSD)and transmiss...The impacts of asymmetric rolling(ASR)and cold rolling(CR)on the creep-aging behavior of AA2219 alloys were revealed by creep deformation experiments,tensile tests,electron backscattered diffraction(EBSD)and transmission electron microscopy(TEM).The ASR specimens under creep stress condition of 1.2σ0.2(σ0.2 is the yield strength)displayed a 50%higher creep strain than the CR specimens.At a creep stress of 0.5σ0.2,the ASR specimens demonstrated remarkably mechanical properties,with a tensile strength of 525 MPa,a yield strength of 338 MPa,and an elongation of 15.2%.This enhancement can be ascribed to the effective grain refinement and promotion of recrystallization after ASR.Notably,ASR resulted in the formation of higher cube textures and a denser forest dislocation structure compared with CR.Additionally,ASR specimens demonstrated a higher density of dispersive,smallerθ′precipitates and larger average Taylor factors compared with CR specimens.展开更多
基金Projects(E2024203001,E2024203049,E2024203071)supported by the Hebei Natural Science Foundation of ChinaProject(236Z1805G)supported by the S&T Program of Hebei,China。
文摘Laser welding is a highly promising joining method for Al alloys.However,certain limitations such as elevated thermal input and keyhole instability are associated with its application in medium-thickness aluminium alloy plates.To address these issues,circular oscillating laser welding combined with post-weld heat treatment was employed to improve the formation quality and mechanical properties of the welds.The effects of the frequency of circular oscillating laser on the forming quality,microstructure,and properties of the welds were analyzed.At an oscillation frequency of 200 Hz,the grain size in the weld zone was reduced compared to single laser welding,and the maximum tensile strength of the weld was observed to reach(264.96±1.33)MPa,representing approximately 61.19%of the base metal.Following the post-weld heat treatment of"solid solution and artificial aging",the grain boundary segregation was diminished.Nanoscale precipitated phases are present in the weld zone.Furthermore,the tensile strength was augmented to(386.35±5.65)MPa,representing approximately 89.23%of the strength of the base metal.The results of this study can provide a theoretical basis and technological reference for the circular oscillating laser welding of medium-thickness 2219-T 6 aluminium alloy plates.
基金Project(JCKY2023205B003)supported by the Defense Industrial Technology Development Program,China。
文摘The creep deformation and mechanical properties of 2219 aluminum alloy were experimentally investigated under both tension and compression at the temperature of 165℃for different time.The results indicated that the creep deformation under tensile stress was greater than that under compressive stress.As the stress level increases,the compressive creep rate showed more significant increase.The yield strength after compressive stress creep-ageing was higher than that after stress-free ageing,with the lowest strength observed in the tensile-aged sample.Overall,the average phase length after compressive stress creep-ageing was larger than after tensile stress ageing.Under tensile stress,the number and size of precipitates at small angles to the stress direction were larger than those perpendicular to the stress direction.In contrast,under compressive stress,this relationship was reversed,and the preferential orientation of phases became more pronounced with ageing time.A unified,physics-based creep-ageing constitutive model,accounting for the orientation of precipitation,was developed for both tensile and compressive stress conditions.The predicted results were in good agreement with the experimental data.These findings,along with the developed model,provide a theoretical and simulation basis for precise creep-ageing forming of components under complex stresses.
基金financial supports from the National Key Research and Development Program of China(No.2021YFB3400900)the National Natural Science Foundation of China(Nos.U22A20190,U2341273,52205435)+2 种基金the Natural Science Foundation of Hunan Province,China(No.2022JJ40621)the Science and Technology Innovation Program of Hunan Province,China(No.2020RC4001)the Project of State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,China(No.ZZYJKT2022-07)。
文摘The impacts of asymmetric rolling(ASR)and cold rolling(CR)on the creep-aging behavior of AA2219 alloys were revealed by creep deformation experiments,tensile tests,electron backscattered diffraction(EBSD)and transmission electron microscopy(TEM).The ASR specimens under creep stress condition of 1.2σ0.2(σ0.2 is the yield strength)displayed a 50%higher creep strain than the CR specimens.At a creep stress of 0.5σ0.2,the ASR specimens demonstrated remarkably mechanical properties,with a tensile strength of 525 MPa,a yield strength of 338 MPa,and an elongation of 15.2%.This enhancement can be ascribed to the effective grain refinement and promotion of recrystallization after ASR.Notably,ASR resulted in the formation of higher cube textures and a denser forest dislocation structure compared with CR.Additionally,ASR specimens demonstrated a higher density of dispersive,smallerθ′precipitates and larger average Taylor factors compared with CR specimens.
