Fatigue life characterization of smooth and notched piping steel specimens in 288/degree/C air environments

Technical Report · Sun May 01 04:00:00 EDT 1988

OSTI ID:5012821

Terrell, J B

Fatigue strain-life tests were conducted on ASME SA 106-B piping steel at 24/degree/C (76/degree/F) and at PWR operating temperature, 288/degree/C (550/degree/F), under completely reversed loading. Smooth specimens were tested at both temperatures whereas specimens containing notches of various acuities were tested at 288/degree/C. Fatigue limits at 10/sup 7/ cycles were estimated to be 185 MPa (26.8 ksi) at 24/degree/C and 232 MPa (33.7 ksi) at 288/degree/C. The difference in fatigue strength observed at the PWR temperature is postulated to be due to dynamic strain aging processes. However, there is a reduction in low cycle fatigue strength at this temperature which results in a decrease in the intended safety factor of the ASME Section III design curve for carbon steels. Notch strain histories were estimated for the notched specimen tests using various interpretations of Neuber's rule. It was concluded that the use of the fatigue notch concentration factor (K/sub f/) in the Neuber relation in conjunction with the uniaxial cyclic stress-strain curve provided the best correlation of notched specimen fatigue data with results obtained from smooth specimen tests. The notched specimen strain-life results derived from the application of Neuber's rule alone proved to be conservative when compared to smooth specimen test results to such an extent that Neuber-generated notch stress and strain amplitudes cannot be compared to the ASME Section III fatigue curves for carbon steels.

• Research Organization: Materials Engineering Associates, Inc., Lanham, MD (USA)
• OSTI ID: 5012821
• Report Number(s): NUREG/CR-5013; MEA-2232; ON: TI88010175
• Country of Publication: United States
• Language: English

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