Dynamic strain ageing in Inconel® Alloy 783 under tension and low cycle fatigue

Dynamic strain aging in Haynes 282 superalloy

“…Such double regions have been observed e.g. in [7]. The subsitutional-related DSA should occur at higher temperatures and lower strain rates, since the diffusivity is considerably lower compared to that of interstitial elements.…”

“…This is well known to occur in precipitation hardened Ni-base superalloys, and has been correlated to the presence of carbon at intermediate temperatures (< 550 • C) [4][5][6][7][8][9] and solute elements (typically Cr or Mo) at higher temperatures (> 550 • C) [6][7][8][9]. Except for the serrated yielding (Portevin-Le Chatelier effect) DSA typically leads to increased stresses and reduced ductility during monotonic loading [10].…”

“…Typical activation energies for DSA in superalloys at intermediate temperatures, where carbon is claimed to be responsible, are in the range 50-130 kJ/mol, see e.g. [4][5][6][7][8][9]. This is usually compared to the activation energy for diffusion of C in Ni (138 kJ/mol for lattice diffusion and 69 kJ/mol for pipe diffusion [18]).…”

“…[6][7][8][9], to be compared with typical activation energies for diffusion of e.g. Fe and Cr in NiFe-Cr (250-300 kJ/mol for lattice diffusion and around 200 kJ/mol for grain boundary diffusion) [23].…”

“…Also, when different methods to estimate the activation energy are compared, the stress drop method usually produces lower values [6,7]. Figure 6 shows bright field TEM images of the dislocation structures in specimens fatigued at 400 and 650 • C. At both temperatures there are clearly visible deformation bands, with band widths in the range 100-200 µm and interband spacing of the same order.…”