Fluorescence Detection and Analysis of Spot Defects in 2196 Aluminum-lithium Alloy Profiles

Abstract

This paper aims at the problem of spot-shaped defects caused by the cleaning process of the profile of 2196 Al-Li alloy, Fluorescence detection combined with metallographic microscope was used for detection, The results showed that the pitting and intergranular corrosion were observed in the pitting defects. Therefore, it is proposed to simulate each cleaning process, analyze the defect morphology generated under different states, and explain the cause of defect formation. The final test results showed that water washing, pickling and water immersion exposure could lead to pitting and intercrystalline corrosion of 2196 Al-Li alloy. Thus, it was analyzed that the defect was caused by the formation of AlCl3 and Al (OH) 3 products after the sample reacted with liquid during the cleaning process. When these two products are more concentrated, The grain boundary is subjected to tensile stress due to volume expansion, It leads to point-like defects in al - Li alloy along grain boundary.