7xxx系铝合金厚板组织与断裂韧性相关性研究
发布时间：2018-10-12 19:37
【摘要】：本文以7085和7055合金为研究对象,采用TEM(透射电镜)、OM(金相显微镜)、SEM(扫描电镜)和EBSD(电子背散射衍射)系统研究了合金在典型时效及固溶工艺处理过程中析出相及晶粒组织的演变规律;以撕裂实验测试UPE值(单位面积裂纹扩展能)为主、紧凑拉伸试样测试KIC值为辅,研究了合金经典型时效及固溶工艺处理后的断裂韧性变化规律;结合断口形貌特征SEM分析,探讨了时效析出相和晶粒组织特征与合金断裂韧性的相关性。主要研究内容及结果如下:撕裂实验测定UPE值与紧凑拉伸试样测定的KIC值在评价时效态7085和7055合金断裂韧性的结果趋势一致,可用于定性表征7xxx系铝合金断裂韧性的高低。合金经不同制度的时效处理后,L-T向和T-L向撕裂实验样品的UPE值变化趋势相同。研究了7085合金厚板经单级时效与双级时效后微观组织与断裂韧性的相关性。结果表明,合金在140℃单级时效过程中,晶内主要的析出相为GP区和η′相。随着时效时间的延长,晶内析出相长大缓慢,晶界缓慢粗化,无沉淀析出带(PFZ)逐渐加宽,合金沿晶断裂比例增加,在达到足够长的时间后有所下降,断裂韧性随时间变化呈先降低后升高趋势。合金经118℃/6h第一级预时效处理后,基体上析出细小的GP区和η′相,晶界析出相连续;随152℃第二级时效时间的延长,晶内析出相不断长大,η相数量呈增加趋势,晶界析出相逐渐断开,PFZ不断加宽,合金沿晶断裂比例先增加后减少,断裂韧性随时间变化呈先降低后升高趋势。研究了7055合金厚板经三级时效后微观组织与断裂韧性的相关性。随着175℃第二级回归时间的延长,晶界析出相不断粗化,从连续到断开,PFZ宽度不断增加,合金的断裂方式由沿晶断裂向穿晶断裂转变,裂纹传播方向逐渐不平行于轧向,韧窝数量增加,断裂韧性逐渐升高。研究了7085合金经固溶处理后晶粒组织与断裂韧性的相关性。在本实验范围内,固溶温度和固溶时间引起的晶粒组织结构变化未对合金断裂韧性产生显著影响。
[Abstract]:In this paper, 7085 and 7055 alloys are studied. The evolution of precipitated phase and grain structure during typical aging and solution treatment were studied by TEM (Transmission Electron Microscopy), OM (metallographic microscope), SEM (scanning Electron microscope) and EBSD (Electron Backscatter diffraction) system. The fracture toughness of the alloy after aging and solution treatment was studied by using tear test UPE (crack growth energy per unit area) and compact tensile specimen (KIC). The fracture toughness was analyzed by SEM. The relationship between aging precipitation phase and grain structure and fracture toughness was discussed. The main research contents and results are as follows: the UPE value measured by tear test is consistent with the KIC value measured by compact tensile specimen in evaluating the fracture toughness of aged 7085 and 7055 alloys. It can be used to characterize the fracture toughness of 7xxx series aluminum alloy qualitatively. After aging treatment, the UPE values of L-T and T-L tearing samples were the same. The relationship between microstructure and fracture toughness of 7085 alloy thick plate after single stage aging and double stage aging was studied. The results show that the main precipitated phases in the alloy are GP region and 畏 'phase during single stage aging at 140 鈩，
本文编号：2267350
[Abstract]:In this paper, 7085 and 7055 alloys are studied. The evolution of precipitated phase and grain structure during typical aging and solution treatment were studied by TEM (Transmission Electron Microscopy), OM (metallographic microscope), SEM (scanning Electron microscope) and EBSD (Electron Backscatter diffraction) system. The fracture toughness of the alloy after aging and solution treatment was studied by using tear test UPE (crack growth energy per unit area) and compact tensile specimen (KIC). The fracture toughness was analyzed by SEM. The relationship between aging precipitation phase and grain structure and fracture toughness was discussed. The main research contents and results are as follows: the UPE value measured by tear test is consistent with the KIC value measured by compact tensile specimen in evaluating the fracture toughness of aged 7085 and 7055 alloys. It can be used to characterize the fracture toughness of 7xxx series aluminum alloy qualitatively. After aging treatment, the UPE values of L-T and T-L tearing samples were the same. The relationship between microstructure and fracture toughness of 7085 alloy thick plate after single stage aging and double stage aging was studied. The results show that the main precipitated phases in the alloy are GP region and 畏 'phase during single stage aging at 140 鈩，
本文编号：2267350
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