Fatigue crack growth material parameters- based on prototype pipe bend test and comparison with conventional parameters.

An experimental study has been performed on a representative prototype-sized pipe bend made of SS 316 LN material to generate the relevant material parameters required for fatigue crack growth (FCG) simulation. Traditionally, FCG numerical simulation material parameters are generated based on specimen level test. In the literature there are many prototype pipe bend test results can be found. However, this paper takes a new look for generating FCG material parameters based on prototype-sized pipe bend test results. A semi-elliptical shaped pre-cracked pipe bend is used for the crack growth studies. Advancement of the crack profile has been measured in a periodic interval of cyclic testing, and the essential crack dimensions are derived to extract the FCG material parameters. FCG response curve derived, based on the prototype sized pipe bend test result, is well below the similar response curve obtained from the conventional material properties. The major reason behind this difference in FCG response is attributed to the influence of the residual stress locked during pipe bend fabrication. Based on these findings, it is recommended to adopt the material parameters derived based on the component-level test for more accurate prediction. Further studies are required to generalise the role of fabrication assisted effects in the material parameters in the case of prototype sized components. • Fatigue crack growth (FCG) experiments on a full-scale prototype-sized SS 316 LN pipe bend have been conducted. • Advancement of the crack profile is measured at periodic intervals and the required crack growth data is extracted. • Material parameters required for FCG simulation are derived based on the test data and FCG response is computed. • This response is compared with those computed based on conventional material parameters. • An approach for predicting a realistic FCG response of power plant piping components is proposed. [ABSTRACT FROM AUTHOR]