Development of GE 1014 Alloy for GP 7200 Low Pressure Turbine Shaft Applications
R. A. Jeniski, Allvac, Monroe, NC; T. D. Bayha, Allegheny Technologies Incorporated (ATI), Monroe, NC
High-strength steel Alloy 1014, was developed and patented by General Electric Aircraft Engines (GEAE) in the 1990ís provide high strength (up to 300 ksi ultimate strength) and fatigue resistance in demanding jet engine applications. Alloy 1014 was designed utilizing both the intermetallic strengthening mechanisms typically associated with maraging steels and alloy carbide strengtheners. The elimination of titanium from the composition significantly enhances the fatigue initiation response over more conventional high strength steels through the reduction of titanium-base nonmetallic inclusions.
GEAE Alloy 1014 is currently the bill of materials for low-pressure turbine engine shafts on the GP 7200 engine, the power plant for the Airbus A380. The 555-seat, double deck Airbus A380 is the most ambitious civil aircraft program yet. When it enters service in March 2006, the A380 will be the world's largest airliner, easily eclipsing Boeing's 747. Using the most advanced technologies, the A380 is also designed to have 10-15% more range, lower fuel burn and emissions, and less noise.
Allvac is manufacturing prototype GP 7200 low-pressure turbine shafts utilizing GEAE Alloy 1014 for application on the A380. A VIM-VAR-VAR triple melt process has been developed to obtain the level of ingot cleanliness required for this demanding application. Ingot cleanliness is of primary importance as these parts are design-limited by low-cycle fatigue properties. The material is forged to a preform shape utilizing both press and radial forging techniques. This paper will present results to date of the development program, including mechanical properties and resultant microstructure in the shaft forgings.