Failure Analysis to Blades of Steam Turbines at Normal Conditions of Operations and Resonance

Abstract

The need to provide quality services, accurate diagnosis, timely rehabilitation and improvement in materials and operation of the turbines, have given way to scientific research crack initiation and crack propagation, the impending fracture and estimating life of the turbine components at normal conditions and resonance. The L-1 stage blades suffer high alternating stresses, for its size, exposure to high temperatures, and mechanical loads under repetitive strain of cyclic load. The lasts stages of blades are also subjected to severe centrifugal loads stress that, when combined with the alternating stress, is responsible for fatigue failures. In this work, the last stage L-1 blades of a steam turbine under cyclic load or fatigue were analyzed, the first instance to observe and measure the initiation crack and propagation crack under normal conditions operation and conditions on resonance; making the comparison to estimate the life time of the blade at both conditions.