An investigation was conducted to determine the suitability of alloy 73J as a turbojet turbine-blade alloy, and the effect of grain size on engine operating life. Blades of alloy 73J were run in a full-scale J33-9 turbojet engine under cyclic conditions. The engine was cycled every 20 minutes, operating 5 minutes at idle and 15 minutes at rated speed. At rated speed, stresses in the critical zone of the blades were 21,000 psi, and the temperature was controlled at 1500° F.nThe 73J turbine blades investigated gave excellent performance, which indicates that further study of this material for turbine blades is warranted. The failure times of the best group of blades ranged from 612 to 1023 hours; and of the worst group, from 484 to 785 hours. The best performance was obtained with the medium-grained group, the intermediate performance with the coarse-grained group, and the poorest performance with the fine-grained group.
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