Many steam turbine blade failures are known to have initiated from corrosion pits. Despite the amount of development that has been undertaken worldwide into corrosion pitting and fatigue failure over the past thirty years, and into the development of computer codes such as BLADE and ANSYS, no predictive methodology yet appears to have been developed for the prediction of corrosion fatigue life of steam turbine blades.This paper describes a program to develop such a procedure. This work involved obtaining certain required test data, initially for dual certified 403/410 12% Cr stainless steel, in a simulated steam environment. Future tests for other blade steels are anticipated when the appropriate test methodology is well established. A technique for blade life estimation will later be developed around the corrosion-fatigue data obtained from these tests. This program required the use of existing corrosion testing facilities and the development of a blade material test facility which can conduct high-cycle fatigue tests on specimens which were load cycled in a simulated operating steam environment, with controlled corrosive conditions. The effects of a number of steady and cyclic stress conditions are being investigated, for the 403SS blade steel at 90°C, and for several levels of corrosive environments. A description of the test program and results to date are presented in this paper.
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