High temperature deformation of nickel base superalloy Udimet 520

Abstract

The high temperature deformation behaviour of nickel base superalloy Udimet 520 was characterised using hot compression isothermal tests. Hot compression tests were conducted between 900 and 1150°C with strain rates of 0 . 001, 0 . 01, 0 . 1 and 1 s 1 . Testing at å 950°C led to sample fracture for all the applied strain rates. The ow behaviour at 1000, 1050 and 1075°C indicated the occurrence of dynamic recovery. For specimens tested at 1100, 1125 and 1150°C, recrystallisation is the softening mechanism. The strain rate sensitivity factor m was estimated for various thermomechanical histories. The activation energy for the hot deformation was determined to be 780 kJ mol 1 . The Zener -Hollomon parameter was also determined and its variation with grain size was studied with deformation conditions. The microstructures of all samples were examined by both optical and scanning electron microscopy. The presence and variations in the morphology and size distribution of deformed and recrystallised grains were determined and related to the deformation conditions.MST/5797

Deformation characteristics of isothermally forged UDIMET 720 nickel-base superalloy

“…The previously estimated apparent activation energy values are far from those reported for deformation of superalloys, i.e., 780 kJ/mol for UDIMET 520 [28] and 400 to 485 kJ/mole for hot deformation of IN718. [19,29,30,31] The reported values for WASPALOY, which is more similar to U720 from a structural point of view, are more scattered and lie in the ln s ϭ 39,666 Fig.…”

Characterization of hot deformation behavior of Haynes230 by using processing maps

“…This value is larger than the activation energies for diffusion of any of the alloying elements contained in Haynes230 or that for self-diffusion in nickel. The similar results have been reported for the other superalloys (Monajati et al, 2005;Bruni et al, 2002;Mashreghi et al, 2004). In the case of Inconel718 nickel base superalloy, the average apparent activation energy was calculated as 443 kJ/mol (Yuan and Liu, 2005).…”

Modeling Grain Size and Strain Rate in Linear Friction Welded Waspaloy

“…The following constitutive equation is often used for relating the flow stress (r) to deformation temperature (T) and strain rate (_ e) in Ni-base superalloys [18,19] :…”