An Experimental and Modelling study of the Evolution of Inelastic Strain and its Implications to Re-crystallisation in Single Crystal Turbine Blades

The overall aim of the project is to develop a microstructure-sensitive constitutive description of creep of gamma prime strengthened superalloys under extreme temperature conditions. The temperature range of interest will be between 1300oC and 1150oC with specific consideration to re-crystallisation during subsequent heat treatment in turbine blades. The work will involve identification of dominant deformation mechanisms and understanding of the microstructure in the conditions of interest, specifically through the use of miniature testing with small gauge volumes of the order of the length scale of micro-segregation. From this information, it is hoped to derive evolution relations for the micro-mechanisms. An appropriate state variable approach will be developed to couple the interaction of the initial microstructure state and its evolution on the creep strain-time trajectories. An emphasis will be placed on experimentally deriving an equation for the inelastic strain that can be used to predict the evolution of plastic strain in modelling activities.