Cyclic temperature creep rupture properties of TP 347H stainless steel tubing

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:418119

Ellis, F V ^[1]

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1. Tordonato Energy Consultants, Inc., Chattanooga, TN (United States)

A series of isothermal creep rupture tests were performed at temperatures of 593 C, 649 C and 704 C on an unexposed TP 347H stainless steel tubing material. The maximum test duration was approximately 17,000 hours. The rupture properties and the minimum creep rate data were correlated using the Dorn parameter. To assess the validity of the life fraction rule, eight rectangular cyclic temperature tests were performed at a constant stress of 124 MPa. For the cyclic temperature tests, the base temperature was 649 C and the peak temperatures were 677 C, 704 C and 732 C. The cyclic times and hold times at the peak temperature were selected to produce ruptures in 1/2, 1/5, and 1/10 of the rupture time at the base temperature. The temperature was recorded for typical temperature changes and used in the life fraction rule calculation. The observed rupture life was slightly greater than the calculated rupture time. In order to account for this observed difference, the relative life concept was used. In the relative life modification of the life fraction rule, the sum of the life fractions at failure is equal to a critical value, the mean relative life. For temperature cycling of TP 347H tubing material, the mean relative life was 1.11. The isothermal creep curves at 124 MPa were fit to a rational polynomial plus steady state creep equation for times up to end of secondary creep. Tertiary creep was described by the tertiary term in the Theta Projection. The cyclic temperature creep curves were calculated using a strain hardening flow rule. Reasonable agreement was found between the observed and calculated time to 0.5%, 1%, 2% and 5% creep strain with mean relative lives from 0.81 at 0.5% to 1.03 at 5%.

• OSTI ID: 418119
• Report Number(s): CONF-960706--; ISBN 0-7918-1779-2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM-NICKEL STEELS
CREEP
EXPERIMENTAL DATA
MECHANICAL TESTS
RUPTURES
SERVICE LIFE