Failure Analysis of a Gas Turbine Blade Made of Inconel 738LC Super Alloy

and critical components of a gas turbine. Blade failures in gas turbine engines often lead to loss of all downstream stages and the power plant will shut down, which can lead to prolonged outages and severe economic loss. In this paper, the failure of a GE-F5 gas turbine blade has been studied by metallurgical and mechanical examinations. The blade was made of a nickel base alloy Inconel 738LC. This blade has fractured after about 65,000 hours of service in one of the Iran’s power plants during operation. Due to the blade failure, the turbine engine was damaged severely. The study was started with a thorough visual inspection of bl ades and continued with hardness measurement, chemical composition checks,and microstructural evaluation as well as examination of the fracture surface. The investigations showed that serious pitting was occurred on the blade surface and there were evidences of fatigue marks in the fracture surface. It was found that the crack initiated by the hot corrosion from the leading edge and propagated by fatigue and finally, as a result of the reduction in cross-section area, fracture was completed.