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 SOUTHWEST RESEARCH INSTITUTE

Gas Turbine Technology Center

Life Evaluation

 

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Failure Modes

To evaluate the life of components, it is essential to identify the probable failure modes for a given component. The possible failure modes for hot section components include thermal mechanical fatigue (TMF), hot corrosion, creep, and coating oxidation and degradation.

 

Engineers at Southwest Research Institute (SwRI) examine the parts using state-of-the-art laboratory facilities. They examine hot section parts failed in service and identify the most probable cause of failure.

 

Life Evaluation Methodology

In gas turbines, the life and integrity of the coatings, applied to protect the components from environmental attack and degradation, govern the life and maintenance intervals of hot section components. SwRI has developed state-of-the-art coating and TMF life prediction methods for several substrate/coating systems. The TMF model has been calibrated with service experience and can be used to predict the life of a specific coating on turbine blades in service.

 

Through an industry consortium program, GTD LIFE software was developed to calculate the remaining life of GE MS5002 engine first-stage buckets. This software is available to turbine users.

 

          Coating Oxidation

          Coating Degradation

photomicrograph showing bond coating oxidation photomicrograph showing bond coating degradation

Photomicrographs showing bond coating oxidation and degradation

 

photograph of a corrosion-attacked area on a frame 5 blade after 40,000 hours of service   flow diagram showing the tasks required to develop a life management system for determining the life of gas turbine components

Photograph of a corrosion-attacked area on a Frame 5 blade after 40,000 hours of service

 

Flow diagram shows the tasks required to develop a life management system for determining the life of gas turbine components. SwRI is one of the few organizations capable of performing each step in the development of these systems.

 

                    Metallography Results

COATLIFE Calculation

image showing in-service degraded coating of a 7FA blade after 21,000 hours of service
Click photo for larger image

 

image showing in-service degraded coating of a 9FA blade after 21,000 hours of service
Click photo for larger image

  graph of COATLIFE calculation

In-service degraded coating of a 7FA blade (left) and a 9FA blade (right) after 21,000 hours of service

 

 

 

COATLIFE validation for Frame 7/9FA blades (GT29+ coating). Model prediction is in good agreement with metallographic results.

 

             Metallography Results

         COATLIFE Calculation

image of 7FA blade after 21,000 hours of service
Click photo for larger image

image of 9FA blade after 17,000 hours of service
Click photo for larger image

graph of COATLIFE calculation
Click graph for larger image

7FA blade after 21,000 hours of service

 

9FA blade after 17,000 hours of service

 

 

 

TMF model validation for Frame 7FA and 9FA blades. Model prediction is in good agreement with metallographic results.

graph showing thermal barrier coating cracking vs time   image of typical interface cracking and crack growth as a function of time

Typical interface cracking and crack growth as a function of time

 

Cracking at the bond coat/ thermal barrier coating (TBC) interface leads to TBC spallation. The results generated at SwRI show that these cracks form at the early stages of component life.

SwRI can offer you a full range of capabilities and experience in gas turbine technology including becoming an extension of your engineering department. For more information about our gas turbine life evaluation capabilities, or how you can contract with SwRI, please contact Klaus Brun, Ph.D., at kbrun@swri.org or (210) 522-5449.

 

gasturbine.swri.org

 

Contact Information

Klaus Brun, Ph.D.

Life Evaluation

(210) 522-5449

kbrun@swri.org

gasturbine.swri.org

Related Terminology

coatings

superalloys

blades or buckets

vanes or nozzles

hot section parts

lifing

coating and material degradation

materials and coatings evaluation

refurbishment

condition assessment

failure analysis

gas turbines

Related Web Sites

IGTI

PRCI

WTUI

Gas/Electric Partnership

Related SwRI Links

Fluids and Machinery Engineering Department

Mechanical Engineering Division

| Fluids and Machinery Engineering Department | Mechanical Engineering Division | SwRI Home |

Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions.

April 15, 2014