Anisotropy of Al-Li alloy plate and its heredity effect in mechanical property distribution of spun-dome

Abstract

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.