Abstract: A 2017 aluminum alloy with high fault energy face centered cubic structure was selected as the research object. Based on the grain size, recrystallization degree and the {111}/{111} near-singular boundary ratio after annealing twin optimization process in grain boundary engineering, a three-factor and three-level orthogonal test was subject to study the effects of aging state (80, 110, 140 HV), rolling deformation (15%, 45%, 75%) and annealing temperature (440, 460, 480 ℃) on the microstructure of the alloy. The grain boundary data of the specimens were measured by the combination of electron back scattering diffraction (EBSD) and five-parameter analysis, and the orthogonal test results were analyzed through range and variance analysis. Based on the range analysis of orthogonal experiments, the main and secondary factors affecting the grain size, recrystallization degree, and the proportion degree of {111}/{111} near-singular boundaries were pointed out successively. Finally, the corrosion performance differences of the three orthogonal test schemes with the ratio of {111}/{111} near-singular boundaries as the main measurement factor were compared by intergranular corrosion test, electrochemical test and overlapping pole map trace analysis. The results show that {111}/{111} near-singular boundaries has good corrosion resistance, which can interrupt the general grain boundary connectivity and inhibit grain boundary corrosion. Therefore, the optimal scheme with a higher proportion of {111}/{111} near-singular boundaries has the best corrosion resistance.

Key words: grain boundary engineering, near-singular boundary, orthogonal test, grain size, recrystallization degree