Open Access

ARTICLE

Role of Residual Stress in Structural Integrity Assessment of Cracked Components at Elevated Temperatures

Kamran Nikbin¹

1 Mechanical Engineering Department, Imperial College, London, SW7 2AZ, UK.

Structural Durability & Health Monitoring 2007, 3(1), 51-68. https://doi.org/10.3970/sdhm.2007.003.051

Abstract

Weldments and welded regions of components are likely to see failure at elevated temperatures earlier than homogenous parent material. In some cases variable loading could also introduce creep/fatigue crack growth. These weld regions not only contain variable creep properties but are likely to contain residual stresses which could relax in time. There are three key factors which may determine a successful outcome for remaining life assessment of engineering components containing residual stresses in the vicinity of welds. The first is standardized testing and measurement procedures. The second is the development of appropriate and accurate correlating parameters to treat the results in a unified and verifiable manner in order to produce `benchmark' material crack initiation and growth properties of weldments. The third is the development of accurate and verifiable models for life assessment of welded components. A short review of available fracture based life assessment codes is presented followed by the description of the correlating parameters employed in fracture based analyses of components at high temperatures. The paper highlights new testing, measurement and predictive procedures which are needed for less conservative life assessment methodologies. The important points relating to the creep crack growth behaviour of weldment specimens, residual stress measurements and modelling of residual stresses are identified. The methodologies are presented and examples of the analysis techniques are applied to feature size components.

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Keywords

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