论文部分内容阅读
利用光学显微镜、扫描电镜、室温拉伸和紧凑拉伸试验对4种不同厚度的7050铝合金板材的显微组织、拉伸性能和断裂韧性进行分析。结果表明:7050合金板材中粗大第二相主要为Al_7Cu_2Fe相和Al_2CuMg相,晶粒组织为不完全再结晶组织;从表层到心部第二相粒子数量增加,尺寸增大,分布变集中,再结晶比例逐渐降低;板材厚度增加,第二相粒子数量增加,尺寸增大,再结晶比例降低,但再结晶晶粒和亚晶尺寸逐渐增大。因此,厚度方向表层到心部,板材的强度和断裂韧性逐渐降低。此外,强度和断裂韧性具有一定的各向异性,同一厚度处L向的强度高于LT向和ST向,L-T向的断裂韧性大于T-L和S-L向。板材厚度增加,强度和断裂韧性降低,并且不同方向的性能差异增大。因此,板材厚度越大,越不利于获得均匀的组织和性能。
The microstructure, tensile properties and fracture toughness of the four kinds of 7050 aluminum alloy plates with different thickness were analyzed by optical microscope, scanning electron microscope, room temperature tensile test and compact tensile test. The results show that the coarse second phase in the 7050 alloy plate is mainly Al_7Cu_2Fe phase and Al_2CuMg phase, and the grain structure is incomplete recrystallization. The number of second phase particles increases from the surface to the core, the size increases and the distribution becomes more concentrated. The proportion of crystal decreases gradually; the thickness of the sheet increases, the number of second phase particles increases, the size increases, the recrystallization ratio decreases, but the recrystallized grains and subgrains size increases gradually. Therefore, the thickness of the surface to the heart, the sheet strength and fracture toughness gradually decreased. In addition, the strength and fracture toughness have a certain anisotropy, the same thickness of the L-direction strength higher than the LT and ST, L-T direction of the fracture toughness than T-L and S-L direction. Plate thickness increases, strength and fracture toughness decrease, and the performance differences between different directions increase. Therefore, the greater the thickness of the sheet, the less conducive to obtaining uniform texture and properties.