Grain Selection in Spiral Selectors During Investment Casting of Single-Crystal Turbine Blades: Part I. Experimental Investigation

Abstract

Spiral grain selectors are used to grow single-crystal (SX) turbine blades during investment casting. Competitive growth in the spiral selectors leads to the selection of a single grain that subsequently grows to form the blade. In this study, the effect of spiral design on grain selection during investment casting was investigated through a series of experiments. It is found that the spiral design can effectively reduce the grain number but is not able to optimize axial grain orientations during solidification, the effectiveness of grain selection is strongly dependent on the spiral ''take-off'' angle, and spirals with smaller take-off angles are most potent. It is proposed that grain selection in the spiral is controlled by the geometry of the spiral via a ''geometrical blocking'' mechanism.

Effects of solute trapping on solidification path in Ta-rich Ta-Al-Fe ternary alloys under rapid freezing

“…The remarkable high temperature strength of Ni-base superalloys is derived from the presence of ordered (super-lattice) precipitates, γ / dispersed in a ductile γ matrix and forming a coherent interface [5]. It had been demonstrated that alloys with super-lattice precipitates exhibited superior deformation and creep behaviour compared to either of the constituent phases and which had formed the basis for the design of these alloys [6,7].…”

Removal of casting defects from CMSX-4®and CMSX-10®alloys by electropolishing in a novel electrolyte; Deep Eutectic Solvent

“…Choline chloride [HOC 2 H 4 N(CH 3 ) 3 Cl] (ChCl) (Aldrich 99%) was recrystallized from absolute ethanol, filtered and dried under vacuum. Oxalic acid dihydrate (OXDH) (Aldrich 99%), was used as received.…”

“…Typical single crystal superalloys castings are manufactured using the vacuum investment casting process; during this process the molten superalloy is poured in a ceramic mould that has been fabricated via the lost wax method [1][2][3][4][5]. The single crystal growth is controlled in part by the speed and temperature at which this mould is removed from the furnace.…”

Large-scale Phase-field Studies of Three-dimensional Dendrite Competitive Growth at the Converging Grain Boundary during Directional Solidification of a Bicrystal Binary Alloy

“…[17][18][19] It is important to clarify 3D grain selection behavior for metallurgy applications and directional solidification products, such as turbine blades. [20][21][22] At present, the phase-field method is the only known method for accurately simulating the dendrite structure during solidification. 15,[23][24][25] However, 3D phase-field simulation of multiple dendrites remains a challenging task owing to the high computational cost, in spite of the development of quantitative phase-field models.…”