Inconel 718, a compressor and turbine wheel material suited for 900–1200°F applications in advanced gas turbine engines, was evaluated for long time properties and structural stability. This work included creep rupture testing and residual tensile property determination after extended times under stress exposure. Tests were conducted at 1000°F to 21,000 hr, at 1100°F to 33,000 hr, at 1200°F to 10,000 hr, and at 1300°F for 6,000 hr. In addition, optical and electron microscopy, X-ray diffraction, and X-ray fluorescence methods of phase analyses before and after exposure were carried out. Except for the expected overaging at 1300°F, there were no detrimental instabilities observed. This alloy has been selected for critical compressor and turbine wheel applications that will see service to 36,000 hr.
KeywordsSigma Phase Stress Rupture Turbine Wheel Short Time Test Columbium
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