Constitutive modeling and springback prediction of stress relaxation age forming of pre-deformed 2219 aluminum alloy

Wang, Kai; Zhan, Lihua; Yang, Youliang; Ma, Zhi; Li, Xicai; Liu, Jian

doi:10.1016/s1003-6326(19)65023-5

Cited by 16 publications

(3 citation statements)

References 18 publications

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“…As the temperature rises to 800~850 • C, the combined effect of diffusion creep and dislocation creep caused by loading in elastic and plastic regions increases the relaxation rate and reduces the threshold stress. Hyperbolic sine function is widely used to describe the evolution of creep strain rate [31]. In conclusion, microstructure, dislocation density and threshold stress determine the pre-strain dependent SR behavior.…”

Section: Creep Strain Model In Stress Relaxation Stagementioning

confidence: 99%

A Unified Constitutive Model of Stress Relaxation of Ti-6Al-4V Alloy with Different Temperatures from Elastic to Plastic Loading

Zhang

et al. 2022

Machines

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The effects of temperature and pre-strain levels on the stress relaxation behavior and corresponding microstructural evolutions of Ti-6Al-4V alloys have been investigated experimentally and numerically in this study. A series of tests (stress relaxation (SR) and repeated stress relaxation (RSR)) and microstructural observations (scanning electron microscope) have been performed, based on which the deformation-related variables, i.e., stress component and activation energy, as a function of the testing time are calculated according to the classical thermal activation theories. The experimental SR behavior and the obtained thermal related variables show that at lower temperatures (700 °C and 750 °C), a large number of dislocations introduced by plastic loading enhance dislocation slip/climb creep, giving rise to rapid relaxation compared with those with elastic loading conditions at the same temperature. At higher temperatures (800 °C and 850 °C), a similar SR phenomenon has been observed at both elastic and plastic loading conditions, which is due to the severe interaction between diffusion creep and dislocation creep after the loading stage. Based on these results, a unified constitutive equation has been proposed to successfully predict the behavior of the whole stress relaxation process composed of the loading stage and subsequent SR stage. The model considering the continuous evolution of internal variables, e.g., dislocation density and lamellar width, in two stages can predict the stress response and microstructure variation with different temperatures from elastic to plastic loading and provide a foundation to effectively optimize the hot forming process combining pre-deformation and stress relaxation.

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Section: Creep Strain Model In Stress Relaxation Stagementioning

confidence: 99%

A Unified Constitutive Model of Stress Relaxation of Ti-6Al-4V Alloy with Different Temperatures from Elastic to Plastic Loading

Zhang

et al. 2022

Machines

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“…During CAF, the sheet metal will be subjected to bending action, causing the stress states changes gradually along the thickness direction. In addition, when the sheet has a large pre-deformation, the deformation texture will be produced, resulting in anisotropy of the deformation and yield strength in different orientations of the panel, which makes the stress distribution more complicated and significantly affects the deformation and properties behavior of the component in the aging process [5] . Therefore, it is important to study the anisotropy creep aging behavior during CAF process.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy in Compression Creep-Ageing Behavior of 2219-T3 Aluminum Alloy

Chen

Zhan

Liao

et al. 2021

SSP

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Creep age forming technology (CAF) has been widely used to manufacture large integral panels in aerospace industry. However, due to the bending of the sheet metal, the stress states usually changes along the thickness direction during the CAF process, resulting in a complex distribution of stress. In addition, deformation texture is introduced when the sheet has a large pre-deformation, which also greatly affects the shape and performance of the component after aging. In this paper, the anisotropy in compression creep-ageing behavior of 2219-T3 aluminum alloy was studied. It was found that there is obvious anisotropy of compressive creep strains, the creep strain is the largest when the applied stress is along the rolling direction (RD) and the smallest when the applied stress is along the transverse direction (TD). The results of room temperature (25 ° C) and high temperature (165 ° C) tensile property test shows that the as-received material properties has obvious in-planar anisotropy, and the yield strength in the RD is the largest, but the 45° and TD are basically the same. Interestingly, the anisotropy of yield strength after SFA and compressive stress creep aging has basically disappeared, that is,the material properties tended to be isotropic after ageing.

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“…The residual stress and yield strength increase with the increase of initial stress. Therefore, the constitutive model considering stress relaxation aging can predict the springback of the stiffened plate in the aging process well [13]. Considering the different internal mechanisms of the small plastic strain and the large plastic strain in the process of bending deformation, a constitutive model was established which can predict the springback angle accurately when used in the L‐bending process [14].…”

Section: Introductionmentioning

confidence: 99%

Influence of artificial aging time on bending characteristics of 6061 aluminum sheet

Wang

Ting

Linyuan

et al. 2020

Materialwissenschaft Werkst

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6061 aluminum alloy has been widely utilized in modern automobile industries with the advantages of low density, good formability and nice machinability. However, the springback phenomena and cross-section deformation problems still remain unsolved. Accordingly, the effect of artificial aging time on the aforementioned bending properties of 6061 aluminum sheet at room temperature were investigated based on the three-point bending test. The mechanical properties of 6061 aluminum alloy was significantly changed by artificial aging treatment, and the bearing capacity of T6-8 h specimen is 2.11 times that of solution heat treatment state specimen when the deflection is the same. With the finite element model verified by experiments, the variation laws of equivalent stress and effective plastic strain of 6061 aluminum sheets in different states were analyzed, and the influence of work hardening exponent n and strength coefficient K on the springback and cross-section deformation were also obtained. The springback increases when the work hardening exponent n decreases gradually, and the uneven deformation increases with the increase of strength coefficient K. With the increase of strength coefficient K, the warpage W P and the thinning rate h increases gradually. As the artificial aging time extends, the springback and cross-section deformation increase.

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Constitutive modeling and springback prediction of stress relaxation age forming of pre-deformed 2219 aluminum alloy

Cited by 16 publications

References 18 publications

A Unified Constitutive Model of Stress Relaxation of Ti-6Al-4V Alloy with Different Temperatures from Elastic to Plastic Loading

A Unified Constitutive Model of Stress Relaxation of Ti-6Al-4V Alloy with Different Temperatures from Elastic to Plastic Loading

Anisotropy in Compression Creep-Ageing Behavior of 2219-T3 Aluminum Alloy

Influence of artificial aging time on bending characteristics of 6061 aluminum sheet

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