Research on the Large Plastic Deformation Damage and Shock Resistance of 7055 Aluminum Alloy

Dislocation damage and adiabatic shear mechanisms of 7055 aluminum alloy during cutting process

“…When the cutting speed is low, neither dislocation initiation nor dislocation movement is suppressed. Hence at a low cutting speed, the dislocations are substantially cross-slipped (Zhang et al., 2018); at high cutting speeds, the dislocation movement is limited by adiabatic shear, but dislocation initiation is not. It is actually the overwhelming constraint and obstructs the cross-slipped dislocation movement, resulting in elongated, unclosed dislocation cells.…”

“…As analyzed above, equation (1) can well describe the cross-slipped dislocation induced by thermal activation under low strain rates, but fails to provide an accurate description of how dislocation cells form under high strain rates (Zhang and Wang, 2018b). Equation (2) can describe the formation of dislocation under low and high strain rates.…”

“…The T6I4-state material retrogresses more easily than the T6-state material. Zhang and Wang (2018a) examined the frictional wear and surface quality of 7055 aluminum alloy in extreme environment with focus on the surface quality and tool–workpiece frictional wear behavior during cutting under ultralow and ultrahigh temperatures, and discovered from the transmission electron microscopy (TEM) microstructure that, when the temperature is –60℃, dispersions in the material become finer, whereas when the temperature is 300℃, many of the dispersions disappear. Despite increasing interest in the cutting process of 7055 aluminum alloy, most of the studies were concentrated on the cutability and frictional wear behavior of the material (Froustey et al., 2017).…”

“…Figure7(a), (b), and (c) shows the TEM bright-field images of the adiabatic shear bands at the cutting speed of 100 m/min, 500 m/min, and 900 m/min, respectively. At 100 m/min, the TEM microstructure of the alloy in the adiabatic shear bands is dominated by 0 precipitates; at 500 m/min, the number density of 0 precipitates decreases sharply, and some of the 0 precipitates are transformed into stable-phase particles completely incoherent with the aluminum matrix(Zhang et al, 2019). At 900 m/min, some of the…”

Size Effects in Internal Friction of Nanocrystalline Aluminum Films

“…The temperature can be increased or decreased during treatment because the coefficients of thermal expansion between the contact layers become uneven and they create mechanical stress fluctuations. When these stresses are greater than the yield stress of the film or become too large [ 1 , 2 , 3 , 4 ], mechanical damage can occur, which could lead to failure.…”