Development of light-weight steel castings for efficient aircraft engines - Summary report

This report summaries the work carried out in the project, LEAN - Development of light-weight steel castings for efficient aircraft engines. The overall object in the project was to develop thinner cast steel components for aircraft engines. The work was conducted in collaboration between research institutes and industry. Swerea SWECAST, the Swedish foundry institute, which has a long tradition in collaboration with the industry in research projects, was the project leader and leader in one of the work packages. FRI, the Polish Foundry Research Institute, which has advance equipment for material science and material data investigations, was the leader of the second work package. The investment foundry TPC Components AB conducted casting trials and contributed with their wide knowledge of investment casting. Casting trials have been performed in order to investigate the influence of different process parameters governing the fluidity of thin walled investment castings. The alloy used was CbCu7-1, i.e. the cast analogy of the stainless precipitation-hardening steel 17-4PH. Two levels of geometry complexity were used as well as top- and bottom gated casting systems. In the first trial, a blade thicknesses ranging from 0.7-2.0 mm was used. In the second trial, some features were added to the blade as well as a textured surface on one side. It was shown that the top gated casting system showed an overall improved fluidity compared to the bottom gated casting system for the simpler geometry. Blade thickness and pouring temperature were shown to have the greatest impact on fluidity. Adding some geometrical features to the simple geometry drastically decreased the differences between the filling systems. Using a one side textured blade with thickness of 1.3 and 1.5 mm was comparable with 1.5 and 2.0 mm flat castings thus reducing weight of the thinnest sections of a steel casting. Predictions of miss-runs with simulations were shown to be in good agreement with experiments and gave valuable insight to problems in the casting trials. Differences in porosity levels were seen between the top- and bottom gated casting systems for the simpler geometry at high metal temperatures, where the former showed a larger amount of porosity. Besides the work performed on fluidity of the cast analogy of 17-4PH, a number of other alloys not commonly used for castings today were evaluated in terms of their fluidity and were compared to 17-4PH. The casting trials were performed with