Lifetime Prediction of High Temperature Components
in cooperation with Alstom
Power, Steam Turbine R&D
In modern steam turbines, high steam temperatures, shorter start-up times and
higher number of start-stop cycles lead to a significant increase of transient
thermal stresses in high temperature components and in particular in the rotors
of high and intermediate pressure modules.
The increase of transient stresses at the rotor surface (leading to greater
LCF and creep damage) is qualitatively illustrated in the figure.
Continuous temperature variation, finite strain rate, creep-fatigue
interaction, multi-axial loading and cyclic material behaviour render the
calculation of the deformation history and the prediction of lifetime at the
critical location a challenging task.
Component like tests are performed to characterise the constitutive
behaviour of 1%CrMoV steel and to assess different damage calculation rules. Novel high temperature experiments
are developed for this purpose.
The complexity of the theoretical lifetime prediction leads to increasing
interest in recent years for the development of damage NDT techniques capable
of quantifying the actual material deterioration level in high temperature
components. Appropriate NDT methods for on-site damage detection in turbine
rotors are developed in this project.
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