(中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 采用光學(xué)顯微鏡、掃描電鏡、透射電鏡、X射線衍射、常溫拉伸和緊湊拉伸實(shí)驗，對120 mm厚的7050鋁合金板材的織構(gòu)分布、拉伸性能及斷裂韌性進(jìn)行分析。結(jié)果表明：沿板材厚度方向，合金的組織、織構(gòu)、強(qiáng)度及斷裂韌性呈不均勻分布；在同一厚度處，合金的強(qiáng)度和斷裂韌性具有明顯的各向異性；由板材表層到中心，粗大第二相及再結(jié)晶晶粒尺寸逐漸增大；板材表層的織構(gòu)主要由剪切織構(gòu){111}á110ñ和立方織構(gòu)Cube{001}á100ñ組成，中心主要由β取向軋制織構(gòu)和少量立方織構(gòu)組成，1/4厚度處是過渡層；由板材表層到中心，軋向及長橫向強(qiáng)度呈不均勻變化，板材中心處強(qiáng)度比表層的小；板材同一厚度處，強(qiáng)度和斷裂韌性具有明顯的各向異性，軋向強(qiáng)度大于長橫向和短橫向強(qiáng)度，L-T取向的斷裂韌性大于T-L取向和S-L取向的斷裂韌性；L-T取向的斷裂方式主要是穿晶斷裂，S-L取向的斷裂方式以沿晶斷裂為主，T-L取向是混合型斷裂，其穿晶斷裂比例比L-T取向的穿晶斷裂比例小, 沿晶斷裂比例比S-L取向的沿晶斷裂比例小。
關(guān)鍵字: 7050鋁合金；不均勻性；各向異性；織構(gòu)；拉伸性能；斷裂韌性
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
