Creep-Rupture Behavior of Six Candidate Stirling Engine Superalloys Tested in Air

The creep-rupture behavior of six candidate Stirling engine iron-base superalloys was determined in air. The alloys included four wrought alloys (A-286, Alloy 800H, N-155, and 19-9DL) and two cast alloys (CRM-6D and XF-818). The specimens were tested to rupture for times up to 3000 h at 650° to 925°C. Rupture life (t_r), minimum creep rate (ε˙_m), and time to 1 percent creep strain (t_0.01), were statistically analyzed as a function of stress and temperature. Estimated stress levels at different temperatures to obtain 3500 h t_r and t_0.01 lives were determined. These data will be compared with similar data being obtained under 15 MPa hydrogen.