PSI - Issue 18

Mikhail Sokovikov et al. / Procedia Structural Integrity 18 (2019) 262–267 Author name / Structural Integrity Procedia 00 (2019) 000–000

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of a plug. The distribution of plastic strains over the rear surface of the specimen during the formation and ejection of the plug was investigated using the CEDIP Silver 450M infrared camera, Sokovikov M.A. at al. (2014) Figure.1 shows the infrared image of the hole after perforation of the specimens made from AMg6 aluminum alloy and the temperature versus coordinate curve plotted at the specified instant of time for the projectile impact velocity of 390 m/s. Resolution of recording along the coordinate (pixel size) is 0.15 mm, time resolution is 0.25 ms. Figure.2 shows the projectile, perforated specimen and ejected plug; the material of the target is AMg6 aluminum alloy. Before conducting the metallographic studies, the specimens were pressed into current conducting bakelite on a CitoPress-10 (Struers) machine and then polished on a Tegramin-30 (Struers) machine. Under rough grinding conditions, distilled water served as a lubricant, while in the final stages a lubricant with highly dispersed particles of silicon oxides was used. The etching was carried out using Keller reagent for 5-10 seconds at a temperature of 65 70°C.

Fig.3. Regions of localization of plastic strain close to the fracture surface in the alloy AMg6 (a,b), as well as the signs of fragmentation of the localized shear structure (c); the speed of the impact of the projectile on the target is 390m/s ; a, b – magnification х6000; c – magnification х16000. Electron microscopic studies of the structure beneath the fracture surface generated after plug ejection from the