Effects of different scanning speeds on microstructure evolution and tribological properties of Inconel 718 alloy vacuum electron beam surface modification

Abstract

In this paper, based on vacuum electron beam surface modification technology, the surface modification experiments of electron beams on Inconel718 plates at different scanning speeds (180 mm/min, 240 mm/min, 300 mm/min, 360 mm/min and 420 mm/min) were studied. The microstructure evolution law and friction and wear properties of electron back scatter diffraction (EBSD) and friction and wear testing machine RTEC (MFT-5000) were analyzed. Then, SEM and EDS were used to study the friction and wear mechanism. The results show that the microstructure of Inconel 718 sample after electron beam surface treatment is divided into basis material (BM), central zone (CTZ) and column zone (CLZ). The grains in the BM region are equiaxial, the grains in the CTZ region are fine strips, and the CLZ region is dominated by short coarse grains. After electron beam treatment, the annealed twins inside the specimen are eliminated, and when the scanning speed is 300 mm/min, the recrystallization ratio is the largest and the orientation difference becomes the most uniform. Different recrystallization textures appeared in different scanning speed specimens, and the textures in the original state are concentrated on copper{112}<111> and S{123}<634 > textures. After electron beam treatment, the texture of the specimen is mainly concentrated in the cubic texture. Experiments have shown that electron beam surface treatment can reduce oxidative wear and adhesive wear of specimens. When the scanning speed is 300 mm/min, the wear volume is the smallest, the wear resistance is the best, and the wear rate is reduced by about 15 % compared with the original specimen. Electrochemical corrosion experiments demonstrated that the relative corrosion rate of Inconel 718 was 1.3 times higher than that of the selected electron beam clad specimens.