Numerical investigations of freckles in directionally solidified nickel-based superalloy casting with abrupt contraction in cross section

ON THE FORMATION OF STRAY GRAINS IN DIRECTIONALLY-SOLIDIFIED NI-BASED SUPERALLOYS WITH VARYING CROSS SECTIONS

Formation of stray grain defects particularly around re-entrant features of the turbine blade airfoils is one of the major problems in directional and single crystal solidification processes. In this work, directional solidification tests of the GTD-111 Ni-based superalloy were conducted at different withdrawal velocities of 3, 6 and 9 mm.min-1 using various stepped cylindrical and cubic design...

Thermomechanical Fatigue Behavior of a Directionally Solidified Ni-Base Superalloy

A continuum crystal plasticity model is used to simulate the material behavior of a directionally solidified Ni-base superalloy, DS GTD-111, in the longitudinal and transverse orientations. Isothermal uniaxial fatigue tests with hold times and creep tests are conducted at temperatures ranging from room temperature (RT) to 1038°C to characterize the deformation response. The constitutive model i...

Corrosion Resistance of Directionally Solidified Casting Zinc-Aluminum Matrix

Fatigue-creep-environment Interactions in a Directionally-solidified Ni-base Superalloy

Directionally-solidified (DS) GTD-111 is a Ni-base superalloy designed to withstand damage occurring in the first and second stage blades of gas-powered turbines. Because of the distinctive microstructure of this material, the manner in which fatiguecreep-environment damage mechanisms interact to initiate cracks is sensitive to grain structure and chemical composition. Along with fatigue cyclin...

Shape Optimization of an abrupt contraction using numerical streamlining

This research was conducted to find a reliable technique to shape an abrupt contraction for minimizing the energy loss. The method may find broader applications in design of variety of transitional cross-sections in hydraulic structures. The streamlines in a 2-D contraction were calculated through solving the potential flow equations in rectangular and curvilinear coordinates. The natural cubic...