Failure assessment diagram analysis of creep crack initiation in 316H stainless steel

In this work the time dependent failure assessment diagram (TDFAD) approach is applied to the study of crack initiation in Type 316H stainless steel, a material commonly used in high temperature applications. A TDFAD has been constructed for the steel at a temperature of 550 °C, and was found to be relatively insensitive to time. The TDFAD procedure is then applied to predict initiation times, at increments of creep crack growth Δa = 0.2 and 0.5 mm, for tests on compact tension specimens and the results compared to experimentally determined values. It has been found that initiation time predictions are sensitive to the creep toughness values, and to the limit load (or reference stress) solution used. Conservative predictions of initiation times have been achieved through the use of the lower bound creep toughness values in conjunction with the plane strain limit load solution. The plane stress limit load solution has given conservative predictions for all bounds of creep toughness used.