Modeling of fatigue crack growth of stainless steel 304L

An effort is made to predict the crack growth of the stainless steel 304L based on a newly developed fatigue approach. The approach consists of two steps: (1) elastic–plastic finite element (FE) analysis of the component; and, (2) the application of a multiaxial fatigue criterion for the crack initiation and growth predictions based on the outputted stress–strain response from the FE analysis. The FE analysis is characterized by the implementation of an advanced cyclic plasticity theory that captures the important cyclic plasticity behavior of the material under the general loading conditions. The fatigue approach is based upon the notion that a material point fails when the accumulated fatigue damage reaches a certain value and the rule is applicable for both crack initiation and growth. As a result, one set of material constants is used for both crack initiation and growth predictions. All the material constants are generated by testing smooth specimens. The approach is applied to Mode I crack growth of compact specimens subjected to constant amplitude loading with different R-ratios and two-step high–low sequence loading. The results show that the approach can properly model the experimentally observed crack growth behavior including the notch effect, the R-ratio effect, and the sequence loading effect. In addition, the early crack growth from a notch and the total fatigue life can be simulated with the approach and the predictions agree well with the experimental observations.