Authors: Yin Zhong Shen, Kyu Hwan Oh, Dong Nyung Lee
Abstract: Tensile specimens cut from the surface layer to the center layer of a 12.7 mm thick 2090 Al-Li alloy plate were solution treated at 550°C for 30 min and subsequently peak-aged at 190°C for 18 h. They were tensile tested along the rolling direction at 25°C at various strain rates. The solution-treated specimens gave rise to serrated flows at a strain rate of 2×10-4 s-1. On the other hand, for the peak-aged alloy, the surface-layer and subsurface-layer specimens underwent complex, serrated flows (fine and coarse types superimposed each other), whereas the center-layer and near-center-layer specimens were devoid of serrated flows. The textures of the surface-layer and subsurface-layer specimens were approximated by the {001}<110> orientation, while those of the center-layer and near-center-layer specimens were approximated by the {011}<211> orientation. The different flow behaviors were discussed based on the crystallographic textures, microstructures and the strain rates.
227
Authors: Yong Lai Chen, Jin Feng Li, Yu Wei Zhang, Zi Qiao Zheng
Abstract: An Al-3.43Cu-1.28Li-0.49Mg-0.12Zr containing 0.62Zn and 0.29Mn was designed and
the microstructures and mechanical properties of the alloy with various heat treatments were
investigated. The precipitates of the alloy consist of T1 (Al2CuLi), θ′ (Al2Cu)
σ (Al5Cu6Mg2) and δ′
(Al3Li). As solution temperature is changed from 485°C to 530°C, the solution degree of alloying
elements in alloy increased, the amount of T1 in the alloy aged at 160°C for 18 h increased and that of
θ′ is decreased, resulting in an increase of strength. After solution treatment at 530°C, the alloy aged
for 18 h at 145°C is mainly strengthened by G P zones, and a little amount of T1 precipitates. As aging
temperature is increased to 160°C and 175°C, the strength increased, due to the sufficient
precipitation of σ and T1. The smaller amount of T1 in the alloy aged at 190°C is consistent with its
lower strength. Meanwhile, it is found that the σ precipitate does not coarsen as aging temperature
increases in the range from 160°C to 190°C.
995
Authors: Yin Zhong Shen, Kyu Hwan Oh, Dong Nyung Lee
Abstract: Flow behavior of the surface and center layers of solution-treated, peak-aged, or
reversion-treated 2090 Al-Li alloy specimens has been reviewed and discussed in terms of
microstructures and textures.
157
Authors: Chun Ping Fan, Zi Qiao Zheng, Min Jia, Ji Fa Zhong, Bin Cheng
Abstract: The microstructure, tensile property and fracture toughness of Al-Li alloy 2397-T87 rolled plate were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, tensile and plane-strain fracture toughness tests. The results show that a pronounced texture variation through the plate thickness was found. Near the surface, Goss texture dominated. While in the center of the plate, typical β fiber texture and a scattering of cube texture were observed. And the subsurface layer exhibited a very weak texture. From the center to the subsurface, the fraction of β fiber texture and cube texture decreased. In contrast, the fraction of shear type texture reaching the maximum in subsurface layer increased. The tensile properties in different layers along the thickness direction were inhomogeneous. The strengths near the surface were lower than those in the center. And the through-thickness strength properties variation in the rolling direction was more remarkable than that in the long transverse direction. In the same thickness layer, the fracture toughness and the strengths were anisotropic. The strengths in the rolling direction were higher than those in the long transverse direction and the short transverse direction, and the strengths in the short transverse direction were the lowest. The fracture toughness in L-T orientation was the highest, followed by that in T-L orientation, and the fracture toughness in S-L orientation was the lowest.
249
Authors: Xu Dong Wang, Yue Wu, Jiong Li Li, Zhao Hui Feng
Abstract: The effect of rolling process on the mechanical property and microstructure of 2A66 Al-Li alloy sheet was investigated. Three different rolling processes for 2A66 AL-Li Alloy Sheet were picked for fatigue crack growth test in T3. The results showed that enhancing the amount of deformation in the range of moderate or reducing the rolling step of rolling process will increase the fatigue crack growth rate.
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