Some applications of analytical TEM to the characterisation of high temperature equipment

Abstract

Much of the high temperature refinery and power generation equipment currently in use in Australia is typically quite old. In many cases plant has been operating for over 20 years, and in a few cases, for 40+ years. Understanding and predicting the behaviour of service-exposed equipment, which has operated at high temperatures and pressures for extended periods, requires a detailed understanding of the material microstructures and properties. Remaining life assessment of aged plant brings to bear a raft of techniques to measure mechanical properties and to look for damage effects. Analytical transmission electron microscopy (AEM), while not a traditional tool for looking at such problems, can provide some useful insights into the microstructural degradation processes which can occur during service, such as carbide coarsening, secondary precipitation and transformation. This paper will highlight some of the potentially useful information which AEM can provide, along with some of its limitations, with reference to refiner pressure vessels, turbine generating rotors, and superheater outlet headers.