| Popis: |
Haynes® 230® is a Ni–Cr–W–Mo alloy commonly used in aerospace and chemical process industries because of its excellent oxidation resistance, fatigue and creep performance at very high temperatures. In this study, the alloy was evaluated as a candidate for its use as tubing material in solar receivers, where coupled thermal-mechanical cycling is imposed in-use by heating imposed during diurnal cycles. The effect of temperature, 425 and 677 °C, and hold times on isothermal fatigue was evaluated and fatigue-life curves were developed for the alloy in its as-received condition and after aging at 677 °C for 3 months. Experimental apparatus and techniques were developed to apply thermomechanical cycles, between 425 and 677 °C, in an expedited manner to determine fatigue life at low strain ranges, again for both material conditions. The influence of stress ratio, R = −1 and R = ∞, was also assessed. The experimental techniques developed and resulting data and findings will be presented. |
