Analysis of the Long-Term Creep-Fatigue Behavior of 2 1/4 Cr-1 Mo Steel

Technical Report · Sat Dec 01 04:00:00 EST 1979

DOI:https://doi.org/10.2172/1649001· OSTI ID:1649001

Booker, M. K. ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Ferritic 2 ¼ Cr-1 Mo steel is one of four materials currently approved for use in elevated-temperature service in nuclear power generation systems by ASME Code Case N-47. The Code Case includes elastic analysis creep-fatigue design curves for the other three materials, but not for 2 ¼ nCr-1 Mo steel. This report details our development of such curves for this material at the request of the ASME Working Group on Creep-Fatigue. We examined available creep-fatigue data by linear summation of creep and fatigue damage, strain range partitioning, and damage rate analysis to guide us in the development of elastic analysis curves. The data are most consistent with the strain range partitioning predictions, but linear summation is the only approach currently recognized by Code Case N-47 for treatment of creep-fatigue analyses. For this reason we primarily developed elastic analysis curves with the linear summation of damage approach. Our other results are presented for comparison only. The linear summation elastic analysis curves are constructed for maximum temperatures of 427, 482, and 538 ^oC (800, 900, and 1000 ^oF) for times of 100, 1000, 10,000, 80,000, and 250,000 h. In addition we constructed 100 h curves for a maximum temperature of 593 ^oC (1100 ^oF). Curves are constructed by using both the damage summation diagram from analysis of experimental data and an assumed damage sum of unity. The damage diagram results are recommended for use. We include final recommended design curves (including Poisson’s ratio correction for ASME Code strain calculation formulae (for potential creep at both ends of the fatigue cycle (no mean stress) and for creep on the compressive end of the cycle (tensile mean stress) only.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1649001
• Report Number(s): ORNL/TM--7068
• Country of Publication: United States
• Language: English

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