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Creep-rupture behavior of candidate Stirling engine iron superalloys in high-pressure hydrogen. Volume II. Hydrogen creep-rupture behavior

Technical Report ·
OSTI ID:6849128

The creep-rupture behavior of nine iron-base and one cobalt-base candidate Stirling engine alloys was evaluated at 650 to 925/sup 0/C in 15 MPa H/sub 2/ and air. The test alloys included six wrought alloys for tube application (CG-27, N-155, 19-9DL, 12 RN72, INCOLOY Alloy 800H, and A-286) and four cast alloys for cylinders and regenerator housing (SA-F11, HS-31, CRM-6D, and XF-818). Two heats of CRM-6D and XF-818 were tested in two different heat treated conditions - CRM-6D (aged vs braze-cycled) and XF-818 (as-cast vs braze-cycled), and SA-F11 and HS-31 with braze-cycle treatment only. Rupture life, minimum creep rate, and time to 1% strain data were analyzed using Orowan-Sherby-Dorn temperature-compensated technique, and the 3500-h rupture life stress and stress to obtain 1% strain in 3500 h were estimated. The analysis indicated that tube alloys CG-27, N-155, and 19-9DL meet the design stress level of 28 MPa for 3500-h rupture life at 870/sup 0/C in 15 MPa, H/sub 2/, and cast alloys HS-31 (braze-cycled), CRM-6D (aged), and SA-F11 (braze-cycled) also adequately meet the design stress of 119 MPa for 3500-h rupture life at 775/sup 0/C in 15 MPa H/sub 2/ for MOD 1A Stirling engine design criteria. The hydrogen environment had no significant adverse effect, compared to air, on 3500-h rupture life stress and stress to obtain 1% creep strain in 3500-h or on minimum creep rates, and in a few cases, a positive effect was noted. However, ductility was adversely affected in hydrogen environment, more for the tube alloys than for the cast materials.

Research Organization:
IIT Research Inst., Chicago, IL (USA)
DOE Contract Number:
AI01-77CS51040
OSTI ID:
6849128
Report Number(s):
DOE/NASA-0303-1; NASA-CR-174705; ON: DE84015152
Country of Publication:
United States
Language:
English