The cyclic stress-strain response of copper at low strains—i. Constant amplitude testing

Cyclic deformation behavior and dislocation structure of Ti-2 at. Pct Al single crystals oriented for double prism slip

“…[23,24,25] This type of secondary cyclic hardening occurs earlier for the higher plastic strain amplitude. [22][23][24][25] Abel noted that for ␥ pl Ͼ 3.8 ϫ 10 Ϫ3 , the cyclic hardening curves of Cu single crystal exhibited a small additional hardening stage that occurred late in saturation before fatigue failure. [23] This hardening stage was accompanied by characteristic changes in the hysteresis loops, which assumed a slimmer more pointed shape.…”

Estimating the amplitude of plastic strain from the distribution of the dislocation morphologies in front of the crack tips

“…Based on the results of Figueroa et al [17] in polycrystals, the dislocation structure is dominated by fatigue cells when the plastic strain amplitude is higher than about 5 × 10 −4 . Similarly, the dislocation dipolar wall is found of between 6 × 10 −5 and 7 × 10 −4 , vein structure exists of between 3 × 10 −5 and 3 × 10 −4 and the dipolar structure applies at lower amplitudes 1 × 10 −6 up to 6 × 10 −5 .…”

“…According to Ackermann et al [2], results of the dislocation structures are dominated by two phases at the plastic strain amplitude location between 10 −3 and 10 −4 for single crystals, and that the dislocation structure is dominated by dislocation cells at a plastic strain amplitude larger than 2 × 10 −3 . At the same time, Figueroa et al [17] point out the relationship between dislocation structure and plastic strain amplitude in polycrystals. Based on the above, it is clear that the dislocation structure is dominated by strain amplitude.…”

The Study of Fatigue Behaviors and Dislocation Structures in Interstitial-Free Steel

“…At the fatigue failure stage of De/2 = 0.125 pct, the small dislocation cells tend to form near the grain boundaries than large dislocation cells; such dislocation structure gradient implies that the sustained cyclic stress for the grain interior and the region near the grain boundary are unequal. Luoh and Chang [22] and Figureoa et al [8] have indicated that the incompatibility induced by neighbor grains will cause the dislocation structures near the grain boundary and in the grain interior to be different. Hence, incompatible stress between the grains should have a significant effect on dislocation development near the regions of grain boundary.…”

“…[1][2][3][4][5][6][7][8] By comparison, fatigued body-centered-cubic (bcc) metals have received less attention concerning the fundamental fatigue mechanisms. With regard to the cyclic hardening behavior for fatigued bcc metals, much of the literature has either merely paid attention to the early and saturated stage of cyclic deformation [9][10][11][12][13][14][15] or outright ignored the secondary cyclic hardening, [5,16] except for the studies of AbdelRaouf et al, [17] Chopra et al, [18] Ikeda, [19] and Shih et al [20] It is well known that the dislocation-cell structure rapidly develops at higher strain amplitudes for cyclically deformed bcc metals.…”