STANDARDISATION OF CREEP/FATIGUE CRACK GROWTH TESTING IN COMPONENTS

In both power generation plants and the chemical industries there is a need to assess the significance of defects which may exist in high temperature equipment operating in the creep and creep/fatigue range. The defect assessment codes [1-4] need verifiable materials data for use in their analysis. The fracture committee in Versailles Agreement for Materials and Standards (VAMAS) has been active in developing and disseminating testing and analysis methodology in this field since 1987. This paper reviews the methods of analysis used in short term small laboratory creep crack growth data and their relevance to long term crack initiation and growth in components. It is clear [4] that industry needs additional justifications in order to accept further the present defect assessment codes. The review of industrial needs indicates that feature component testing which best simulates the stress state of the actual component should be used to validate the failure predictions and increase confidence in defect assessment codes. It is therefore concluded that a standardisation programme for testing and analysis would be relevant. The programme objectives for VAMAS TWA25 committee on ‘Creep/fatigue crack growth of components ’ are reviewed and conclusions are presented as to the future developments