Advances have been made in the use of Finite Element (FE) simulation techniques to estimate the creep failure life of components operating at high temperature. The High Temperature Performance (HTP) Research Group at the University of Nottingham has developed new continuum damage mechanics approaches for predicting the creep damage in and around pipe welds. The experimental test data supplied by the WELDON industrial partners have been used to create creep constitutive laws that were used to predict the damage and rupture life of pressurised pipes. The continuum damage approach will be extended to deal with other types of welds used in high temperature pipe applications. The work has resulted in several publications in international journals and conferences.
Within the project creep data set was generated for both P22, P91 and respective weld metals under test conditions typical of those found in high temperature plants. Although not entirely innovative concerning testing conditions it adds additional data and knowledge to existing materials databases, which will help improving the understanding of materials behaviour under those conditions. This result has immediate use in design and assessment of high temperature components thus improving work on both the manufacturing and services areas.
ENSA has achieved a better knowledge about the weldability and influence of the welding parameters on the creep properties of the P22 and P91 steels. In addition the measurement of residual stresses by the blind hole method and its verification with the X rays technique has given us a better understanding of our manufacturing process.
The High Temperature Performance (HTP) Research Group at the University of Nottingham has developed new procedures for simulating the weld process using Finite Element (FE) techniques. This approach allows the simulation of thermal-mechanical interaction of each weld bead, resulting in the prediction of the overall residual stresses in the weld. The WELDON project has provided a valuable set of experimental measurements that have been used to verify the FE simulations. The weld simulation techniques will continue to be improved and have already been applied to other types of high temperature pipe welds used in power generation plant. The work has resulted in a number of publications in international journals and conferences.