Course Overview
The gas turbine is one of the most
technologically advanced energy conversion devices. The first
working models were introduced in 1939 in both aviation and in
electric power production and had turbine inlet temperatures on the
order of 1100 F and employed uncooled, heat resisting steel turbine
blades. Today turbine inlet temperatures are in the range of 2700 F
(1500 C) for the G & H class utility combustion turbines and in
excess of 3000 F (1650 C) for commercial flight engines. These
remarkable increases in the gas turbine firing temperature have been
made possible in part by substantial advances in hot section airfoil
materials, coatings and manufacturing technology during the past
seventy years.
This workshop will discuss the
development history, manufacturing processes, application and
refurbishment of the high temperature materials and coatings used in
gas turbine engines with particular emphasis on hot section
superalloy component manufacture and refurbishment. The metallurgy
of nickel and cobalt based superalloys will be discussed and the
many steps involved in investment casting manufacture, from wax
pattern & ceramic core production, shell build, equiaxed, DS or
single crystal vacuum casting and post cast operations will be
reviewed. This will include review of advances in cooling
configurations, casting imperfections, inspection methods and
general acceptance criteria. Specific challenges related to making
large F, G & H-class components and sophisticated air cooled, single
crystal aero-engine airfoils will be noted. The widespread use of
thermal barrier coatings has brought great focus to the issue of
coating selection. The various types of gas turbine hot section
coatings, their selection criteria and manufacturing method used
will be discussed.
The benefits of repair and
refurbishment of engine run parts is well established. The increased
complexity and high replacement cost of hot section components has
placed greater importance on development of innovative component
repair schemes. Participants will learn methods of assessing
component damage experienced from service exposure, typical
degradation modes observed and the techniques used to analyze the
remaining life of components removed from service. The various
component repair technologies utilized to restore components will be
discussed in detail (ie dimensional checks, coating removal
techniques, HIP and rejuvenation heat treatments, weld repair,
diffusion brazing processes and component re-coating) as will
quality assurance methods and procedures to verify the refurbished
components meet industry standards. The workshop includes many case
study examples of component refurbishment and the last section is
devoted to a workshop where attendees develop component repair
solutions. Participants are encouraged to submit questions in
advance regarding repair issues faced in their jobs.
Learning Objectives
After completing the course the
participants should be able to explain:
1.
What makes superalloys especially suited
for gas turbine components
2.
Understanding of the distinction between
conventional casting and directional solidification
3.
How different damage mechanisms
(oxidation, corrosion, erosion) affect the component
4.
Advantages & disadvantages of the many
types of protective coatings
5.
How high cycle fatigue & low cycle
fatigue damage is caused, prevented, and repaired
6.
Various heat treatments used in repairs,
and why they are important
7.
Critical quality control steps in
component manufacture and repair
8.
How to reliably extend the service life
of valuable components
Who Should Enroll?
Typically technical staff, engineers
and technicians responsible for various aspects of gas turbine
design, upgrade, manufacture, repair, analysis, operations, or
maintenance will attend. A must for GT repair shop personnel,
insurance companies, coatings suppliers, GT OEM designers and
technical staff.
Course Highlights
This seminar will cover superalloy
materials, airfoil manufacture, protective coatings, component
damage experienced from service exposure, techniques used to analyze
the remaining life of components removed from service, component
repair technologies, and quality assurance of repairs. The seminar
includes many case study examples and the last section of the
seminar is devoted to a workshop where attendees develop component
repair solutions. Participants are encouraged to contact the
instructors prior to the course with potential applications or
problems that can be discussed as case studies.
Course Outline
· Gas
Turbine Overview
o
Gas Turbine Engine Designs
o
Typical Gas Turbine
Components, Materials and Coatings
o
Gas Turbine Airfoil
Materials, Coatings and Airfoil Design Trends
· Materials
and Metallurgy
o
Superalloy Metallurgy
o
Evolution of Superalloy
Materials Technology
o
Production of Superalloys
o
Investment Casting of
Equiax, DS and Single Crystal Airfoils
o
NDT Inspection, Criteria
and Acceptance Standards
· Gas
Turbine Coatings
o
Superalloy Surface
Stability
o
Comparison of
Oxidation/Corrosion protection
o
Manufacturing Methods and
Requirements
o
Diffusion vs. Overlay
Coatings
o
Thermal Barrier Coatings
· Degradation
of Gas Turbine Components
o
Metallurgical Effects of
Service
o
Creep
o
High Cycle Fatigue
o
Low Cycle Fatigue
o
Environmental Degradation
· Why
repair and refurbish parts?
o
Cost Benefit of Repairs
o
Repair Market Trends
o
The Future for Industrial
Frame GT Repairs
· Component
Evaluation: The evaluation of used components and determination of
the repair/refurbishment process will be discussed.
o
Timing and selection of
components for analysis
o
Micro structural analysis
o
Mechanical testing –Stress
Rupture bars
o
Coating Evaluation
o
Hot Corrosion Attack
o
Failure Analysis
o
Component Management
Program
o
Determine Damage
Mechanisms, the Extent of Damage, Root Cause of Damage, and
Corrective/Preventive Action
· Refurbishment
& Repair Processes: Procedures and techniques used to restore
components to industry standards
o
Typical Damage
o
Coating Stripping
o
Dimensional Checks
o
Re-Coating Selection and
Processes
o
HIP and Rejuvenation Heat
Treatments
o
Superalloy Weld Processes
o
Diffusion Brazing
· Quality
Assurance: Methods and procedures to verify components meet industry
standards
o
QA Certification
o
Quality Plan
o
QA Inspections
o
NDE Defect Criteria
o
Dimensional Specification
o
NDE Inspections
· Case
Studies & Problem Solving:
o
Case studies presented by
the instructors to illustrate the process of component repair &
refurbishment. The class will then be divided into teams and given
components for which they will
determine the best process
· Round
Table Discussion:
o
Round table discussion
regarding the latest repair trends and student questions.
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