Ashutosh Kannawar SKNCOE (Vadgaon)

TE Mech -2SEAT NO:T120360925

A Seminar on

Presented by

Failure Analysis of

Gas turbine blades

Propulsion system

compressor

-Draw air&compress&deliver in combustion chamber

INTRODUCTION

Aerodynamics Mechanical Thermal load Design ,Manufacturing Material selection Assembly etc COMMON MODE OF FAILURE: -Fatigue failure

Failure of stator blades

After disassembling the engine after a test run

Take blade &analyse it, using visual&stereo binocular method

Stereo zoom microscope is used

FAILURE OF STATOR BLADES OF COMPRESSER

Fracture from hub region at leading edgeCrack extends from fracture to centre of

aerofoil sectionFatigue failure Crack origin near junction of the airofoil

&stem region at leading edge side

OBSERVATIONS

Blade Failure Pattern

Machining marks

Creates stress concentration

So fatigue crack occur

Compressor blade found to have failed in progressive mode i.e.by fatigue

Crack originate at blade hub-stem junction at the leading edge side

Presence of machining cracks is reason for failure

CONCLUSION

To avoid stress concentration avoid machinig marks

Avoid abrassive marks

RECOMMENDATION

What are the blades:individual component which makes turbine section of gas turbine & blades extract energy from gas produced by combuster

Different materials are used like nickel ,cobalt

disadvantage of it :more complicated &costly.also system must be strong to resist high pressure

GAS TURBINE BLADES

Desirable properties:corrosive resistant ,strong

-cobalt (earlier used )

-nickel (most common)

Previosly cobalt is used

MATERIAL OF TURBINE BLADE

Life is measured in hours before failure of blade

Cobalt based blade have 50,000 hrs lifeNickel based blade have 15,000 hrs life Also nickel based blades can work at high

temperature

LIFE

Failure cause :-microstructural changes-void formation-environmental effectChemical damage

FAILURE ANALYSIS OF IN-738LC BLADE

Equipment –optical emission spectrometerEDS analyzerThree sections method(transverse)1)at root2)mid point3)top of airofoil

EXPERIMENTAL TECHNIQUE

PROCEDURE:

1)Take a blade which is failed2)Apply three sections method 3)Put the blade below optical emission

spectrometer4)Observe microstructure

Hardness increases as we move towards fracture

Ductility of the blade decreases due to high temperature

Chemical compossition of blade is same as IN-738LC super alloy

RESULT:

Gamma phase dissolve & disapper with increasing distance from root

Crack growth is interdendritic

Hardness increases in fracture zone

CONCLUSION: