(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 采用光学显微镜、扫描电镜、透射电镜、X射线衍射、常温拉伸和紧凑拉伸实验，对120 mm厚的7050铝合金板材的织构分布、拉伸性能及断裂韧性进行分析。结果表明：沿板材厚度方向，合金的组织、织构、强度及断裂韧性呈不均匀分布；在同一厚度处，合金的强度和断裂韧性具有明显的各向异性；由板材表层到中心，粗大第二相及再结晶晶粒尺寸逐渐增大；板材表层的织构主要由剪切织构{111}á110ñ和立方织构Cube{001}á100ñ组成，中心主要由β取向轧制织构和少量立方织构组成，1/4厚度处是过渡层；由板材表层到中心，轧向及长横向强度呈不均匀变化，板材中心处强度比表层的小；板材同一厚度处，强度和断裂韧性具有明显的各向异性，轧向强度大于长横向和短横向强度，L-T取向的断裂韧性大于T-L取向和S-L取向的断裂韧性；L-T取向的断裂方式主要是穿晶断裂，S-L取向的断裂方式以沿晶断裂为主，T-L取向是混合型断裂，其穿晶断裂比例比L-T取向的穿晶断裂比例小, 沿晶断裂比例比S-L取向的沿晶断裂比例小。
关键字: 7050铝合金；不均匀性；各向异性；织构；拉伸性能；断裂韧性
fracture toughness of 7050 aluminum alloy thick plate
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The texture distribution, tensile property and fracture toughness of 7050 aluminum alloy thick plate were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, tensile and toughness tests. The results show that the microstructure，texture，tensile property and fracture toughness are inhomogeneous in different layers along the thickness direction. At the same thickness, the tensile property and fracture toughness show appreciable anisotropy. From the surface to the center, the average sizes of the coarse second phase particles and recrystallization grains increase. Near the surface of the plate，typical shear textures {111}á110ñ and cube textures {001}á100ñ are observed, while the center of the plate shows typical β fiber texture with a scattering of cube texture. The quarter layer of the plate seems to serve as a transition layer. From the surface to the center, the strength is inhomogeneous in the rolling direction and long transverse direction. The strength in the center is smaller than that on the surface of the plate. The strength and fracture toughness show appreciable anisotropy at the same thickness. The strength in the rolling direction is higher than that in the long transverse direction and the short transverse direction, and the fracture toughness in the L-T orientation is higher than that in the T-L and S-L orientations at the same thickness. The fracture mode in the L-T orientation is trangranular fracture, and in the S-L orientation the fracture mode is intergranular fracture. In the T-L orientation, the fracture mode is a mixed fracture, the fraction of the trangranular fracture is lower than that in the L-T orientation, and the fraction of the intergranular fracture is lower than that in the S-L orientation.
Key words: 7050 aluminum alloy; inhomogeneity; anisotropy; texture; tensile property; fracture toughness
