7050-T7651铝合金厚板显微组织及力学性能不均匀性

Inhomogeneity of microstructure and mechanical properties of 7050-T7651 aluminum alloy thick plate

采用金相显微镜、扫描电镜、透射电镜和力学拉伸试验机,研究160 mm 7050-T7651铝合金特厚板不同厚度位置的金相组织、晶粒取向、织构类型、时效纳米析出相分布以及力学性能的差异。结果表明:从板材表层到心部,组织中的第二相粒子含量降低,但尺寸增加;板材表层以小角度晶界亚结构组织为主,小角度晶界比例在79%~85%之间,而板材心部小角度晶界的比例为58%左右,相比于板材表层小角度晶界比例降低了26.6%~31.8%;板材表层以{001}<110>剪切织构为主,占比为3.64%,并随厚度增加,变形织构组分含量逐渐增多;板材厚度方向力学性能呈现出沿厚度表层-心部-表层方向先降低后升高的趋势,且力学性能最优位置均为板材表层位置。

The differences in the microstructure,grain orientation,texture type,aging nano precipitate phase distribution and mechanical properties of 160 mm 7050-T7651 aluminum alloy extra-thick plate at different thickness positions were studied by means of metallographic microscope,scanning electron microscope,transmission electron microscope and mechanical tensile test.The results show that from the surface to the center of the plate,the content of the second phase particles in the microstructure decreases,but the size increases;The surface layer of the plate is mainly composed of small angle grain boundaries.The proportion of small angle grain boundaries ranges from 79%to 85%,while the proportion of small angle grain boundaries in the center of the plate is about 58%,which is a decrease of 26.6%to 31.8%compared to the proportion of small angle grain boundaries on the surface layer of the plate;The surface layer of the plate is mainly characterized by{001}<110>shear texture,accounting for 3.64%.As the thickness increases,the content of deformation texture components gradually increases.The mechanical properties of the plate in the thickness direction show a trend of first decreasing and then increasing along the thickness surface-center-surface direction,and the optimal positions for mechanical properties are all located at the surface of the plate.