Fracture analysis of a low pressure steam turbine blade

Ernst Plesiutschnig; Patrick Johannes Fritzl; Norbert Enzinger; Christof Sommitsch

doi:10.1016/j.csefa.2016.02.001

Fracture analysis of a low pressure steam turbine blade

Ernst Plesiutschnig, Patrick Johannes Fritzl, Norbert Enzinger, Christof Sommitsch

Institute of Materials Science, Joining and Forming (3030)

Research output: Contribution to journal › Article › peer-review

Abstract

Cracks were analysed at the root of the third blade row of low-pressure steam turbine blades of different natural frequencies. The root cause of the fatigue crack initiation was pitting corrosion of the forged ferritic/martensitic X20Cr13 material. Metallographic investigations, finite element analysis and fracture mechanics analysis combined with experimental data from the literature are used to evaluate crack propagating stresses to discuss the operating conditions. The calculations show that corrosion pits at the root of the turbine blade increase the local stresses above yield strength. Excitation of natural frequencies by changing the rotor speed is not responsible for the crack propagation. The centrifugal load and superimposed bending load caused by unsteady steam forces are responsible for the crack propagation.

Original language	English
Pages (from-to)	39-50
Number of pages	11
Journal	Case Studies in Engineering Failure Analysis
Volume	5-6
DOIs	https://doi.org/10.1016/j.csefa.2016.02.001
Publication status	Published - 2016

Keywords

Turbine blade
Pitting corrosion
FEM
1.4021 (AISI 420)

Fields of Expertise

Advanced Materials Science

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10.1016/j.csefa.2016.02.001

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@article{5889349aa39f4f4583275828c151e604,

title = "Fracture analysis of a low pressure steam turbine blade",

abstract = "Cracks were analysed at the root of the third blade row of low-pressure steam turbine blades of different natural frequencies. The root cause of the fatigue crack initiation was pitting corrosion of the forged ferritic/martensitic X20Cr13 material. Metallographic investigations, finite element analysis and fracture mechanics analysis combined with experimental data from the literature are used to evaluate crack propagating stresses to discuss the operating conditions. The calculations show that corrosion pits at the root of the turbine blade increase the local stresses above yield strength. Excitation of natural frequencies by changing the rotor speed is not responsible for the crack propagation. The centrifugal load and superimposed bending load caused by unsteady steam forces are responsible for the crack propagation.",

keywords = "Turbine blade, Pitting corrosion, FEM, 1.4021 (AISI 420)",

author = "Ernst Plesiutschnig and Fritzl, {Patrick Johannes} and Norbert Enzinger and Christof Sommitsch",

year = "2016",

doi = "10.1016/j.csefa.2016.02.001",

language = "English",

volume = "5-6",

pages = "39--50",

journal = "Case Studies in Engineering Failure Analysis",

issn = "2213-2902",

publisher = "Elsevier B.V.",

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TY - JOUR

T1 - Fracture analysis of a low pressure steam turbine blade

AU - Plesiutschnig, Ernst

AU - Fritzl, Patrick Johannes

AU - Enzinger, Norbert

AU - Sommitsch, Christof

PY - 2016

Y1 - 2016

N2 - Cracks were analysed at the root of the third blade row of low-pressure steam turbine blades of different natural frequencies. The root cause of the fatigue crack initiation was pitting corrosion of the forged ferritic/martensitic X20Cr13 material. Metallographic investigations, finite element analysis and fracture mechanics analysis combined with experimental data from the literature are used to evaluate crack propagating stresses to discuss the operating conditions. The calculations show that corrosion pits at the root of the turbine blade increase the local stresses above yield strength. Excitation of natural frequencies by changing the rotor speed is not responsible for the crack propagation. The centrifugal load and superimposed bending load caused by unsteady steam forces are responsible for the crack propagation.

AB - Cracks were analysed at the root of the third blade row of low-pressure steam turbine blades of different natural frequencies. The root cause of the fatigue crack initiation was pitting corrosion of the forged ferritic/martensitic X20Cr13 material. Metallographic investigations, finite element analysis and fracture mechanics analysis combined with experimental data from the literature are used to evaluate crack propagating stresses to discuss the operating conditions. The calculations show that corrosion pits at the root of the turbine blade increase the local stresses above yield strength. Excitation of natural frequencies by changing the rotor speed is not responsible for the crack propagation. The centrifugal load and superimposed bending load caused by unsteady steam forces are responsible for the crack propagation.

KW - Turbine blade

KW - Pitting corrosion

KW - FEM

KW - 1.4021 (AISI 420)

U2 - 10.1016/j.csefa.2016.02.001

DO - 10.1016/j.csefa.2016.02.001

M3 - Article

SN - 2213-2902

VL - 5-6

SP - 39

EP - 50

JO - Case Studies in Engineering Failure Analysis

JF - Case Studies in Engineering Failure Analysis

ER -

Fracture analysis of a low pressure steam turbine blade

Abstract

Keywords

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