Cracks on the Roots of Turbine Blades of the Low-Pressure Turbine in a Steam Power Plant Fußrisse an Turbinenschaufeln der Niederdruckturbine eines Dampfkraftwerkes

Cracks were found in the roots of steam turbine blades of the third blade row (LA-2) of the low-pressure turbine during revision works in a coal-fired power plant. Metallographic examinations reveal pitting corrosion sites, branched cracks, and local plastic deformation at the root of the first load bearing flank radius. The fracture surface was analyzed using light microscopy and scanning electron microscopy (SEM). Finite element (FE) simulations were performed in order to qualitatively represent the stress peak positions on the blade root.