Simulation of the creep behaviour of P92 sandwich structures at 650°C with loading transverse to the intermediate layer

Abstract

Abstract Improving thermal efficiency in modern steam turbines can be achieved by the application of new cooling systems, such as sandwich structures, which enable cooling steam to flow without severe losses during operation. In a preliminary investigation a cooling structure was developed which combines an interlayer of a woven wire mesh between two plane sheets. An exact knowledge of the mechanical behaviour, especially the creep behaviour, of the so called Grid Sheet structures, manufactured from the ferritic chromium steel P92, is essential for an adoption in a new built combined cycle power plant. In order to characterise and simulate the mechanical behaviour of the structures, creep tests with loading transverse to the intermediate layer were carried out and used as a reference for the simulated results. In this work the creep behaviour was simulated with the finite element method using creep law material parameters determined from bulk material. A model for a prediction of the point of time when single weld joints collapse was introduced.