EBSD Analysis of Fatigue Crack Growth of 2124 Aluminum Alloy for Aviation

运用电子背散射衍射(EBSD)分析技术对2124-T851铝合金板材的疲劳裂纹扩展进行了分析研究。结果表明,疲劳裂纹扩展以穿晶为主,随晶粒取向的不同而呈现一定的择优性。当裂纹扩展到晶界时,由于相邻晶粒间存在的取向差,裂纹会偏离其正常扩展路径而发生偏转,而晶内的裂纹偏转则更多是因为粗大第二相粒子在循环应力作用下协调变形能力差引起的。裂纹扩展过程中发生裂纹分叉与特定的晶体学方向有关,是由于裂纹尖端多个等效{111}<110>滑移系的同时开动造成的。

EBSD Analysis of Fatigue Crack Growth of 2124 Aluminum Alloy for Aviation

The fatigue crack growth of 2124-T851 aluminum alloy was investigated by Electron Backscatter Diffraction (EBSD) analysis. The result shows that the mode of fatigue crack growth is mainly transcrystalline, and the preferential orientation changes with the difference of grain orientation. When the crack extends to the grain boundary, the deflection of the crack against the normal extensive path will take place as a result of the misorientation of adjoining grains, but the deflection of the crack in the grain inner is mainly caused by the coarse second phase particles which are poor in coordination of deformability under cyclic stress. The phenomenon of bifurcation during the process of the crack propagation is relative with the specific crystallographic direction, which is caused by the simultaneous movement of numerous equivalent {111}<110> slip system on crack-tip.