2297-T87铝合金厚板力学性能的各向异性与厚向不均匀性

Mechanical Anisotropy and Inhomogeneity through Thickness of 2297-T87 Aluminum Alloy Thick Plate

通过拉伸试验、金相显微镜、X射线衍射、扫描电镜和透射电镜分析研究了85 mm厚的2297-T87铝合金厚板力学性能的各向异性与厚度方向的不均匀性。结果表明:在2297-T87合金厚板L方向上力学性能沿厚度层呈不均匀性,从表层到中心强度逐渐提高,而LT方向性能变化不明显;织构沿厚度方向分布不均匀,厚板中心主要是β纤维成分和部分的Goss织构;而表层除了少量变形织构,还存在再结晶织构;T/8厚度为大量的剪切织构;T/4厚度层是一个过渡层,同时存在少量再结晶织构、剪切织构和β纤维。同一厚度层不同方向的力学性能各向异性较为明显,强度和塑性的变化趋势一致:L>LT>ST。这种各向异性与晶粒结构和第二相粒子有关。

The mechanical anisotropy and inhomogeneity through thickness of 2297-T87 aluminum alloy thick plate of 85 mm in thickness were investigated by tensile test, optical microscopy, X-ray diffractometry, scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The results show that the mechanical properties in L orientation are inhomogeneous in different layers along the thickness direction, and the strength increases from the surface to the center. However, the difference of LT orientation is not significant. Meanwhile the texture distributes nonuniformly through thickness. The centre of the plate is mainly β fiber texture and Goss texture, while besides deformation texture, the recrystallization texture is observed near the surface. In the T/8 layer, the fraction of the shear texture is maximal. The T/4 layer seems to serve as a transition layer, presenting a small amount of the recrystallization texture, shear texture and β fiber texture at the same time. At the same thickness, the anisotropy of mechanical properties is obvious. There is reasonable concordance between changes of the strength and plasticity： L〉LT〉ST. The anisotropy is associated with the grain structure and the second phase particles.