JOM

This research work is based on a specially developed SiO2-free shell mold system for the investment casting of NiAl alloys. Hitherto, this shell system has only been used for scientific work on small, laboratory scale samples made of IC75 alloy. The main focus of the research is to examine the feasibility of upscaling of the shell mold system for production scale samples. For this reason, 200 mm long dummy turbine blades were cast. Nondestructive analysis of the castings by visual examination of the blades’ surface quality, computed tomography scans of their internal structures and three-dimensional measurements showed very good results for the shell mold system. In particular, the good dimensional stability of the shell mold with average deviations of +0.3 mm and a local maximum deviation of −0.73 mm are excellent for a water-soluble shell mold system. The results of this work demonstrate that the investigated mold system is suitable for large samples and melt weights of up to 5 kg and is thus adaptable for the production process of NiAl components.

Several systems are described in which the computer is used as an aid for analyzing creep-rupture data. In the CADCAPS system the basic test parameters are measured as electronic signals that can be used as input information for a small on-line computer. The data can be displayed as creep (strain vs time) curves or in numerous other forms. In our present systems data collection and data processing are performed separately. The data-collection systems include (1) manually collected data that are keypunched onto cards and (2) electronic transducer signals that are fed through a multichannel recorder to an analog-to-digital converter, punched on paper tape, and transferred to magnetic tape. In both cases large central computers are used to process the data to obtain tabulations and plots of strain versus time for each test. Several methods for storing and sorting the creep test data are described.