Cast Turbine Blades Research Articles

Simulation of Superalloy Castings

With the assistance of versatile computer programs, simulation of controlled heat flow during the solidification of precision superalloy vacuum castings has evolved to high levels of sophistication. Using these modeling technologies, researchers hope to simulate the solidification of a complex turbine blade casting.

The effect of volume percent of fine γ’ on creep in Ds Mar-M200 + Hf

A correlation was found to exist between creep life at 1800∮F (1255 K) and the volume percent of uniformly dispersed fine (<0.5 μm) gamma prime (γ’) precipitate in direction-ally solidified (DS) Mar-M200 + Hf turbine blade castings. A three-fold increase in creep-rupture life was realized when the amount of fine γ’ increased from about the 30 pct level to approximately a 45 vol pct level. Heat treatment studies revealed that the amount of finey’ developed in this alloy is strongly dependent on solution temperature, especially in the range from 2160 to 2210∮F (1455 to 1483 K). Higher solution temperatures promote the development of greater amounts of fine y’ by more complete solutioning of the coarse γ’ and eutectic γ-γ’ constituents which subsequently reprecipitate as fine y’ upon cooling and aging.

High definition radiography of cast turbine blades as a method of detecting and evaluating the incidence of microporosity

An X-radiographic method is described which employs an image enlargement technique to measure microporosity. Using an extremely small focal spot, the Harwell E12 High Definition X-ray Unit is able to detect individual pores as small as 0.03 mm. A testing speed of 1000 blades per week is achieved using a fast detector system instead of conventional fine grained X-ray film.

Integrally Cast Airfoil Components for Small Gas Turbine Engines

In the past two decades, remarkable progress has been made in investment casting of airfoil components for gas turbine engines. Cast turbine blades, operating at high stresses and high temperatures, have been widely accepted. Improved production techniques, notably vacuum melting and casting, have stimulated development of greatly improved nickel and cobalt based superalloys. Although individual turbine blades and vanes have been produced in large quantities since 1950, a more recent development is high-volume production of integrally cast turbine wheels and nozzles for small gas turbine engines. This paper is a review of the state of the art in integrally cast airfoil components. The Monoshell process, as applied to integral castings is reviewed and representative illustrations of a wide range of engine castings are presented.