| Abstract Scope |
Due to its exceptional high-temperature properties, Alloy 709, an advanced stainless steel, has been selected for qualification as a Class A construction material in the ASME Boiler and Pressure Vessel Code for high-temperature reactor applications. This effort includes a staged qualification plan, focusing on developing a data package for material-specific design parameters. A key component is to conduct fatigue and creep-fatigue tests at elevated temperatures to establish a creep-fatigue interaction diagram (D-diagram). This presentation summarizes strain-controlled fatigue and creep-fatigue testing results at 816 °C (1,500 °F) on three commercial heats of Alloy 709. Tests cover strain ranges from 0.25 to 3 % and creep-fatigue tensile hold times up to 10 hours. The fatigue design curve and the creep-fatigue interaction analysis of Alloy 709 at 816 °C (1,500 °F) will be presented. Additionally, microstructural evaluations and fracture analyses were conducted to complement the understanding of creep-fatigue damage mechanisms in Alloy 709. |