Comparison of near threshold fatigue crack growth data by Kmax-constant method with the post-construction codes

Abstract

In this paper we obtain near threshold fatigue crack growth (FCG) data for several carbon steels and type 304 stainless steel by the K max-constant method. Since the FCG rate obtained by the K max-constant method is considered to give the upper limit of the FCG data obtained by the stress ratio-constant method, this data was compared with the FCG evaluation diagrams given in the ASME and Japan Society of Mechanical Engineers (JSME) pressure vessel post-construction codes to ensure their validity. Though the FCG rate for carbon steel S55C was somewhat affected by the K max value, the results show that the obtained near threshold FCG data is close to the upper bound of the JSME code diagram, which is an extrapolation of the ASME FCG diagram to the near threshold region.