Metallurgical Failure Analysis

Part1- Fundamentals and Methodology

1 Introduction

2 Fracture

2.1 Ductile and Brittle Fractures

2.2 Fractography of Ductile and Brittle Fractures

2.3 Fatigue Fracture

2.4 Fractography of Fatigue Fracture

3 Tools and Techniques Used in Failure Analysis

3.1 Acquisition of Background Data

3.2 Selection of Samples

3.3 Photographic Records

3.4 Preliminary Examination

3.5 Non-Destructive Testing

3.6 Chemical Analysis

3.7 Fractography, Microscopy and Energy Dispersive Analysis

By X-Ray (EDAX) Using Scanning Electron Microscope

3.8 Optical Microscopy

3.9 Electron Probe Micro Analysis (EPMA)

3.10 X-Ray Diffraction

3.11 Evaluation of Mechanical Properties

Part2 - Case Studies

4 Improper Material Selection

4.1 Failure of Hip-joint prosthesis

4.2 Failure of Firing pin of 120mm Low Range Mortar

4.3 Failure of Shaft of a Gearbox

4.4 Failure of 7.62mm Cartridge Cases

4.5 Failure of Fin Mounting Nuts

5 Manufacturing Defect

5.1 Failure of Track Pins of Track Link

5.2 Failure of Track Shoe of an Infantry Combat Vehicle

5.3 Failure of Control Lever of Fuel Metering Unit of an

Aero Engine

5.4 Failure of Drill Rods for Mining

5.5 Failure of Lifting Lugs of a Missile

5.6 Failure of Breech Block of Light Machine Gun

5.7 Failure of Titanium Sponge Cutting Ring

6 Casting Defects

6.1 Failure of Exhaust Outer Cone of an Aero Engine

6.2 Failure of Sealing Rings of Centrifugal Breather of

an Aero Engine.

6.3 Failure of Grinding Rolls of Bowl Mill of a Thermal Power

Station.

7 Overload

7.1 Failure of Mounting Bolt of Emergency Changeover Valve

7.2 Failure of Steam Pipe in Unit-VI of a Thermal Power Station

7.3 Failure of Body of Saddle Assembly

7.4 Failure of Boiler Tube of a Thermal Power Station

8 Fatigue

8.1 Failure of Wheel Hub of an Aircraft

8.2 Failure of Bolts of Flapjack Mounting Bracket of an Aircraft

8.3 Failure of Compressor Rotor Blades of an Aero Engine

8.4 Failure of Bearing Cage of an Aero Engine

9 Corrosion Induced Failures

9.1 Failure of Nipple of Fuel Pipe Line

9.2 Failure of Condenser Tubes of Thermal Power Station

9.3 Failure of High Pressure Air and Hydraulic Pipes

9.4 Failure of Detonator of a Grenade

10 Hydrogen Embrittlement and Stress Corrosion Cracking

10.1 Failure of Fin Mounting Screws

10.2 Failure of Differential Valve Cover of Fuel Metering Unit

10.3 Failure of Lever Assembly of Main Undercarriage of an

Aircraft

10.4 Failure of Cartridge Seat Ejection Secondary of an Aircraft

11 Wear

11.1 Failure of Inter-Rotor Bearing of an Aero Engine

11.2 Failure of Low Temperature Super Heater Tube of

a Thermal Power Station

11.3 Failure of Main Landing Gear Assembly of an Aircraft

11.4 Failure of Coupling Shaft and Bevel Gear of an Aero Engine

12 Elevated Temperature Failures

12.1 Failure of a Bolt of Nozzle Guide Vane of an Aero Engine

12.2 Failure of Vanes of Front Nozzle Diaphragm Assembly of an

Aero Engine

12.3 Failure of Centre Main Bearing of an Aircraft Engine

12.4 Failure of Jet Nozzle Casing of an Aero Engine.

12.5 Failure of Turbine Stator Vanes of an Aero Engine

13 Bibliography