Session: CS-08-01 ASME Code Section XI Activities-1

Paper Number: 123490

123490 - Effect of Temperature on the Fatigue Crack Growth Rates of Austenitic Stainless Steels in an Air Environment for Asme Code Section Xi 

Fatigue crack growth rates da/dN for stainless steels in air environment are provided by the ASME Boiler and Pressure Vessel Code in Section XI. The fatigue crack growth rates are given by da/dN = C_F(DK)ⁿ, where C_F is the fatigue crack growth rate coefficient, n is the fatigue crack growth rate exponent and DK is the stress intensity factor range. The coefficient C_F consists of a temperature parameter, S_T, and a scaling parameter, S_R, which is a function of the stress ratio, R.

A function for the S_T parameter is given in Appendix Y of ASME Code Section XI:

S_T = 10^{[-8.714 + 1.34E-3 x T + 3.34E-6 x T^2 + 5.95E-9 x T^3]}

where T = temperature in °C

However, the functional form is cumbersome and the original basis for the temperature function is questionable, consisting mostly of testing outside of the bounds of the temperatures of interest to its application in ASME Code Section XI Appendix Y.

Following a review of the literature for test data at temperatures more directly relevant to the Code, the function of the temperature parameter is reviewed.  An alternative equation for S_T for stainless steels in an air environment is proposed for ASME Code Section XI, Appendix Y, based on the literature experimental data surveyed in this study.

Presenting Author: Andrew Morley Rolls-Royce Plc

Presenting Author Biography: Andrew Morley is a Structural Integrity Specialist with 15 years of experience in the nuclear sector with Rolls-Royce. Andrew has particular interests in structural reliability and through-life degradation mechanisms relevant to nuclear plant.

Authors:

Andrew Morley Rolls-Royce Plc
Martin Negyesi Centre for Advanced and Innovative Technologies – VŠB-Technical University of Ostrava
Kunio Hasegawa Japan Atomic Energy Agency