AA 7055铝合金板材的微观组织与力学性能

研究AA 7055-T7751板材不同厚度层的力学性能,并采用电子背散射衍射(EBSD)、透射电子显微镜(TEM)、小角度X射线散射(SAXS)等分析技术研究板材不同厚度层的微观组织。结果表明:从板材表层到厚度中心,再结晶程度从69%下降到19.1%,亚晶粒尺寸从10μm减小到2μm;板材厚度中心主要为轧制型织构,远离中心层其含量逐渐减少,板材表层主要为剪切型织构;板材主要强化相为盘状η'相,其盘面半径为3.7 nm,厚度为1~3 nm,与基体的共格应变约为0.0133;板材不同厚度层沿轧制方向的拉伸屈服强度近似呈线性变化:σ_y=-38.7S+604.8(0≤S≤1)。

Microstructure and Mechanical Property of Aluminum Alloy Plate AA 7055

Through-thickness microstructure and mechanical property of AA 7055-T7751 aluminum alloy plate were investigated by u-sing electron backscattered diffraction (EBSD),transmission electron microscope (TEM)and small angle X-ray scattering(SAXS). The results indicate an inhomogeneous distribution of microstructure through the thickness.The degree of recrystallization decreases gradually from 69% to 19.1%,as deepening from the surface to the center of the plate.The size of subgrains decreases from 10 μm at the surface to around 2 μm at the center.Strong texture of rolling type is observed near the center but the intensity decreases gradually as nearing the surface and the shear texture becomes the dominant.High density of plate-like η′phases are observed in the alloy,indi-cating the sufficient precipitation.η′precipitates of this condition are around 3.7 nm in radius,1-3 nm in thickness and are found co-herent with the Al matrix with a coherent strain of 0.0133,showing a strong strengthening effect.The heterogeneity in grain scale does not influence the distribution and the morphology of precipitates.The yield strength (L direction)varies linearly along the thickness di-rection of the plate,fitting an equation of σy =-38.7S +604.8 (0≤S≤1).The variation of yield strength is related to the heteroge-neity of grain structure.