To study the impact of V-notch radius on the mechanical properties of TA15 titanium alloy，tensile，stress-rupture，fatigue tests and fracture analysis are conducted on both smooth specimens and those with varing V-notch radii. By using the finite element method，the distribution of the stress-strain field at the notch is analyzed，the relationship between the stress-strain field and the notch strength，stress-rupture time，fatigue life and fracture behaviour of TA15 titanium alloy are further investigated. The results show that under static loading，as the notch radius decreases from 0.85 mm to 0.15 mm，both the tensile strength and stress-rupture time of TA15 titanium alloy increase，while the proportion of the shear-plastic zone in fracture decreases. Stress triaxiality around the notch initially increases and then decreases as it extends inward from the root of the notch，as determined by finite element analysis. The fracture originates from the peak position of stress triaxiality （near the notch root）. During the prolonged stress-rupture tests，stress redistribution around the notch occurrs，resulting in a strengthening effect at the notch. Under dynamic loading，the fracture surface of the notched specimen exhibits multi-source crack propagation. Different stress concentrations and gradients around the notch result in varying degrees of fatigue damage. As the notch radius decreases，the size of the critical fatigue damage area decreases，effective stress increases，leading to a decrease in fatigue life and the proportion of crack propagation zones.
The mechanical properties and grain structures of 2A55 Al−Li alloy plate with 20 mm in thickness after T6-aging at 165 °C for 24 h were investigated. The aging precipitates, grain structures and mechanical property distribution along the circumferential and axial directions in the T6-aged spun-dome with 1 m in diameter spin-deformed through the 2A55 Al−Li alloy plate with 20 mm in thickness were studied. The precipitates in the T6-aged dome include a great number of T1 (Al2CuLi) precipitates and a small number of δ′ (Al3Li) and θ′ (Al2Cu) precipitates. The distribution of T1 precipitates is uneven, which is characterized by dense distribution at subgrain boundaries and the formation of precipitate-free zone (PFZ) at high angle grain boundaries. The T6-aged plate possesses almost same strength along a same direction, but there exists anisotropy with the lowest strength along 45° direction and the highest strength along the rolling direction. The T6-aged dome possesses great mechanical property discrepancy along a same circumferential direction and axial direction, which is correlated with the variation of the angle of the dome circumferential direction and axial direction to the rolling direction and the resulting different textures and grain aspect ratio at different locations. There exists a heredity effect in the grain structures and mechanical properties from the original hot-rolled plate to the subsequent spin-deformed dome.
