Failure Analysis Master Course V1

University of Ljubljana

Slovenia

Failure Analysis

Master Course

Borut KOSEC, Ale NAGODE, Gorazd KOSEC

Ljubljana, in January 2014

B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)

1

Case Histories of Materials Failure

Is failure analysis really necessary?

Why not just replace an item of equipment each time it fails?

Why spend a lot of time analyzing the failure?

The basic reason for studying failures is to reduce costs and thereby increase profits.

Nine questions should be asked in every failure analysis:

What is the material?

What are its mechanical properties?

What are its physical properties?

How was it made?

How long was it used?

What was it designed to do?

To what environment was it exposed?

What properties have changed?

What was the mechanism of failure?

Broken


2

Causes of Failures

Failures are caused by design errors or deficiencies in one or more of the following

categiries:

1. Design deficiencies

Failure to adequately consider the effect of notches

Inadequate knowledge of service loads and environment

Difficulty of stress analysis in complex parts and loadings

2. Deficiency in selection of material

Poor match between service conditions and selection criteria

Inadequate data on material

Too much emphasis given to cost and not enough to quality

3. Imperfection in material due to manufacturing

4. Overload and other abuses in service

5. Inadequate maintenance and repair

6. Environmental factors

Conditions beyond those allowed for in design

Deterioration of properties with time of exposure to environment

Corrosion. (Image courtesy of Norbert Wodhnl Norbert Wodhnl)


3

Engineering components fail in service in the following general ways:

1. Excessive elastic deformation

2. Excessive plastic deformation

3. Fracture

4. Loss of required part geometry through corrosion or wear.

Broken teeth of a cement mill

Techniques of Failure Analysis

When the problem of determining the cause of a failure and proposing corrective action

must be faced, there is definite procedure for conducting the failure analysis.

Frequently a failure analysis requires the efforts of a team of people including experts in

material behaviour, stress analysis, and vibrations, and sophisticated structural and analysis

techniques.

Scanning Electron Microscope (SEM) JEOL 5610


4

Field Inspection of the Failure

The most useful first approach is to inspect the failure at the site of the accident as soon as

possible after the failure occurs. This site visit should be lavishly documented with

photographs; for very soon the accident will be cleared away and repair began. It is best to

take the photographs in color. Start taking pictures at a distance and move up the site of the

failure. Shoot pictures from several angles. Careful sketches and detailed notes help to

orient the photographs and allow you to completely reconstruct the scene months or years

later when you are in design review or a courtroom.

The following critical pieces of information should be obtained during the field inspection:

1. Location of all broken pieces relative to each other

2. Identification of the origin of failure

3. Orientation and magnitude of the stresses

4. Direction of crack propagation and sequence of failure

5. Presence of obvious material defects, stress concentrations, etc.

6. Presence of oxidation, temper colors, or corrosion products

7. Presence of secondary damage not related to the main failure.

Aircraft acident


5

It is important to interview and maintenance personnel to get their version of what

happened and learn about any unusual operating history, such as unusual vibrationor noise

prior to failure. Whenever possible, the failure should be brought back to laboratory for

more detailed analysis. Any cutting that is required should be done well away from the

fracture surface so as not to alter that surface. Whenever possible, samples should be

obtained from identical material or components that did not fail. Samples of process fluids,

lubricants, etc. should be obtained for corrosion-related failures. Be sure to label all pieces

and key their identification to your notes.

Great care should be exercised in preserving the fracture surface. Never touch the fractured

surfaces, and do not attempt to fit them back together. Avoid washing a fracture surface

with water unless it has been contaminated with seawater or fire-extinguisher fluids. To

prevent corrosion of a fracture surface, dry the surface with a jet of water-free compressed

air and place the part in a desiccator or pack it with a suitable desiccant.

When the failure surface can not be removed from the field for investigation in the

laboratory, it is necessary to take the laboratory into the field. A portable metallographic

laboratory has been developed for such a situation.

The cracks appeared on the working surface of the die


6

Background History and Information

A complete case history on the component that failed should be developed as soon as

possible. Ideally, most of this information should be obtained before making the site visit,

since more intellegent questions and observations will result. The following is a list of data

that need to be assembled:

1. Name of item, identifying numbers, owner, user, manufacturer or fabrication

2. Function of item

3. Data on service history, including inspection of operating logs and records

4. Discussion with operating personnel and witnesses concerning any unusual

conditions or events prior to failure

5. Documentation on materials used in the item

6. Information on manufacturing and fabrication methods used, including any

codes or standards

7. Documentation on inspection standards and techniques that were applied

8. Date and time of failure; temperature and environmental conditions

9. Documentation on design standards and calculations performed in the design

10. A set of shop drawings, including any modifications made to the design

during manufacturing or installation.

Fractured pipe (Image courtesy Prof. Robert Akid, School of Engineering, Sheffield)


7

Comparison of Basic Nondestructive Inspection Methods

Method Characteristics Detected Advantages Limitations Example of Use

Visual-Optical Surface characteristics such

as finish, scratches, cracks,

or color; stain in transparent

materials

Often convient; can

be automated

Can be applied only

to surfaces, through

surface openings, or

to transparent material

Paper, wood, or

metal for surface

finish and

uniformity

Liquid penetrant Surface openings due to

cracks, porosity, seams, or

folds

Inexpensive; easy to

use; readly portable;

sensitive to small

surface flaws

Flaw must be open to

surface; not useful on

porous materials

Turbine blades for

surface cracks or

porosity

Magnetic particles Leakage magnetic flux

caused by surface or near-

surface cracks, voids,

inclusions, or material

geometry changes

Inexpensive;

sensitive both to

surface and near-

surface flaws

Limited to

ferromagnetic

materials; surface

preparation and post-

inspection

demagnetization may

be required

Railroad wheels

or tracks

Radiography Changes in density from

voids, inclusions, material

variations; placement of

internal parts

Can be used to

inspect wide range

of materials and

thicknesses;

versatile; film

provides record of

inspection

radiation safety

requires precautions;

expensive; detection

of cracks can be

difficult

Pipeline welds for

penetration,

inclusions, voids

Ultrasonics Changes in acoustic

impendance caused by

cracks, nonbonds,

inclusions, or interfaces

Can penetrate thick

materials; excellent

for crack detection;

can be automated

Normally requires

coupling to material

either by contact to

surface or immersion

in a fluid such as

water

Adhesive

assemblies for

bond integrity

Eddy currents Changes in electrical

conductivity caused by

material variations, cracks,

voids, or inclusions

Readily automated;

moderate cost

Limited to electrically

conducting materials;

limited penetration

depth

Heta exchanger

tubes for wall

thinning and

cracks

Ultrasonic analysis of the rod


8

Thermography Case study: House

220,0C

1000,0C

400

600

800

1000

Thermography Case study: Inductive heating

Thermography Case study: Steel slab heattreatment


9

Basic Types of Deformation and Fracture

Deformation

Time independent

Elastic

Plastic

Time dependent

Creep

Fracture

Static loading

Brittle

Ductile

Environmental

Creep rupture

Fatigue: Cyclic Loading

High cycle

Low cycle

Fatigue crack growth

Corrosion fatigue

Broken spring of the Golf V


10

Relation between common failure modes and

conditions that produce the failure

Types of loading Types of stress

Failure modes Static Repeated Impact Tension Compression Shear

Brittle fracture x x x x

Ductile fracture x x x

High-cycle fatigue x x x

Low-cycle fatigue x x x

Corrosion fatigue x x x

Buckling x x x

Gross yielding x x x x

Creep x x x x

Caustic or hydrogen

embrittlement

x x

Stress - corrosion

cracking

x x x

Operating temperatures

Failure modes Low Room High Criteria generally useful for selection of material

Brittle fracture x x Charpy V-notch transition temperature; notch

toughnes; KIctoughness measurements

Ductile fracture x x Tensile strength; shearing yield strength

High-cycle atigue x x x Fatigue strength for expected life, with typical stress

raisers present

Low-cycle fatigue x x x Static ductility available and the peak cyclic plastic

strain expected at stress raisers during prescribed life

Corrosion fatigue x x Corrosion-fatigue strength for the metal and

contaminant and for similar time

Buckling x x x Modulus of elasticity and compressive yield strength

Gross yielding x x x Yield strength

Creep x Creep rate or sustained stress rupture strength for the

temperature and expected life

Caustic or hydrogen

embrittlement

x x Stability under simultaneous stress and hydrogen or

other chemical environment

Stress - corrosion

cracking

x x Residual or imposed stress and corrosion resistance to

the environment


11

Failure modes for mechanical components

1. Elastic deformation 9. Impact

2. Yielding a. Impact fracture

3. Brinelling b. Impact deformation

4. Ductile failure c. Impact wear

5. Britttle failure d. Impact fretting

6. Fatigue e. Impact fatigue

a. High-cycle fatigue 10. Fretting

b. Low-cycle fatigue a. Fretting fatigue

c. Thermal fatigue b. Fretting wear

d. Surface fatigue c. Fretting corrosion

e. Impact fatigue 11. Galling and seizure

f. Corrosion fatigue 12. Scoring

g. Fretting fatigue 13. Creep

7. Corrosion 14. Stress rupture

a. Direct chemical attack 15. Thermal shock

b. Galvanic corrosion 16. Thermal relaxation

c. Crevice corrosion 17. Combined creep and fatigue

d. Pitting corrosion 18. Buckling

e. Intergranular corrosion 19. Creep buckling

f. Selective leaching 20. Oxidation

g. Erosion-corrosion 21. Radiation damage

h. Cavitation 22. Bonding failure

i. Hydrogen damage 23. Delamination

j. Biological corrosion 24. Erosion

k. Stress corrosion

8. Wear

a. Adhesive wear

b. Abrasive wear

c. Corrosive wear

d. Surface fatigue wear

e. Deformation wear

f. Impact wear

g. Fretting wear


12

Damage Mechanisms and Fovourable Microstructural Properties of the

Tool Material

Damage mechanism Favourable microstructural properties

mechanical loading

high hardness

suitable fracture toughness

mechanical loading at elevated

temperatures high hot hardness

high thermal stability of the microstructure

fatigue (repeated mechanical

loading)

high hardness

high fatigue resistance

fine microstructure

low content and small size of internal defects

wear abrasion high hardness

high volume fraction, optimum size and distribution

of hard wear resistant particles

adhesion high hardness

oxide layer at the surface

low chemical reactivity between tool and work

material

surface fatigue high hardness

high fatigue resistance

high temperature high thermal stability of the microstructure

high oxidation resistance

thermal cycling high thermal stability of the microstructure

high hardness at elevated temperatures

high creep resistance

high resistance against plastic cycling

low thermal expansion

high oxidation resistance


13

Automotive Failures

Component Failure Distribution

Component %

Engine 41

Drivetrain 26

Suspension 13

Chassis / Body 7

Steering 7

Braking System 3

Hidraulics 3

Distribution of Causes

Cause %

Abuse 29

Manufacturing / Design 21

Failed Repair 18

Age 10

Raw Material 9

Accident Damage 7

Failed Modification 3

Storage Procedures 3


14

Materials Selection

There are no magic formulas for materials selection.

Successful materials selection depends on the answers to the following questions:

Have the performance requirements and service environments been properly and

completely defined?

Is there a good correlation between the performance requirements and the material

properties used in evaluating the candidate materials?

Has the relation between properties and their modification by subsequent manufacturing

process been fully considered?

Is the material available in the shapes and configurations required and at an acceptable

price?

The Materials Selection Process

The selection of materials on a purely rational basis is far from easy. The problem is not

only often made difficult by insufficient or inaccurate property data, it is typically on of

decision making in the face of multiple constraints without clear-cut objective function.

A problem of materials selection usually involves of two different situations:

1. Selection of the materials for a new product or new design.

2. Reevaluation of an existing product or design to reduce costs, increase reliable improve

performance, etc.


15

Materials Selection, like any other aspect of engineering design, is a problematic

process.

The steps in the materials selection process can be defined as follows:

Analysis of the materials requirements. Determine the conditions of service and

environment thet the product must withstand. Translate them into critical material

properties.

Identification and screening of candidate materials. Compare the needed properties

(responses) with a large materials property data base to select a few materials that look

promising for the application.

Selection of candidate materials. Analyze candidate materials in terms of tradeoffs of

product performance, cost, fabricability, and availability to select the best material for

the application.

Development of design data. Determine experimentally the key material properties for

the selected material to obtain statistically reliable measures of the material performance

under the specific conditions expected to be encountered in service.

The Khafji rig disaster. (Image courtesy of Thomas Brinsko with Bic Alliance Magazine.)


16

Presenting Technical Information

The purpose of presenting technical information is to convey technical ideas, facts, and

opinions between people. It is also a tool of persuasion.

There are allways several different ways to present any set of technical information.

The challenge is to find simple ways to present hard ideas. This leads to five main

principles of information presentation:

1. Use graphical methods of communication wherever possible,

2. Supplement algebraic and mathematical information with geometry to

make it simple and/or clearer,

3. Use visual models to portray ideas,

4. Do not be frightened to make approximations where necessary, and

5. Using sketches, diagrams, and drawings (of various types).

Steps in Writing a Technical Paper and/or Report

The five operations involved in the writing of a high-quality technical report and/or report

are best remembered with the acronym POWER:

P Plan the writing

O Outline the report

W Write

E Edit

R Rewrite


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Technical paper usually have an outline similar to this:

Abstract

Introduction

Experimental procedure

Experimental results

Discussion

Summary and/or conclusions

Acknowledgments

Appendixes

Tables

Figures

Formal Technical Report

A formal technical report usually is written at the end of a project.

Generally, it is a complete, stand-alone document aimed at persons having widely diverse

backgrounds. Therefore, much more detail is required.

The online of a typical formal report might be:

Covering letter (letter of transmittal)

Summary (containing conclusions)

Introduction (containing background to the work to acquiant reader with the problem

and the purpose for carrying on the work)

Experimental procedure

Discussion (of results)

Conclusions

References

Appendixes

Tables

Figures


18

LITERATURE

BOOKS

Source Book in Failure Analysis, ASM International, Metals Park Ohio, 1974.

S. Kalpakjian: Tool and Die Failures - Source Book, American Society for Metals; Metals Park, Ohio, 1982.

J. Broichhausen: Schadenskunde: Analyse und Vermeidung von Schden in Konstruktion, Fertigung und Betrieb, Carl Hanser Verlag, Mnchen/Wien, 1980.

R.D. Barer, B.F. Peters: Why Metals Fail, Gordon and Breach Science Publishers, New York/London, 1970.

V.J. Colangelo, F.A. Heiser: Analysis of Metallurgical Failures, John Wiley & Sons Inc., New York/London, 1974.

D.J. White: Understanding How Components Fail, ASM International, Metals Park, Ohio, 1999.

A.F. Lin: Structural Life Assessment Methods, ASM International, Metals Park, Ohio, 1998.

P.F. Timmins: Solutions to Equipment failures, ASM International, Metals Park, Ohio, 1998.

Handbook of Case Histories in Failure Analysis, Volume 1, ASM International, Metals Park, Ohio, 1992.

Handbook of Case Histories in Failure Analysis, Volume 2, ASM International, Metals Park, Ohio, 1992.

ASM Handbook Volume 11: Failure Analysis and Prevention, ASM International, Metals Park, Ohio, 1986.

ASM Handbook Volume 19: Fatigue and Fracture, ASM International, Metals Park, Ohio, 1996.

D.N. French: Metallurgical Failures in Fossil Fried Boilers, John Wiley & Sons Inc., New York, 1993.

R.D. Port, H.H. Herro: The Nalco Guide to Boiler Failure Analysis, Nalco Chemical Company, McGraw-Hill Inc., New York, 1991.

H.M. Herro, R.D. Port: The Nalco Guide to Cooling Water Systems Analysis, Nalco Chemical Company, McGraw-Hill Inc., New York, 1991.

O.J. Horger: ASME Handbook: Metals Engineering Design, McGraw-Hill Book Company Inc., New York, 1953.

K.-H. Schwalbe: Bruchmechanik metallischer Werkstoffe, Carl Hanser Verlag, Mnchen/Wien, 1980.

J. Lemaitre: A Course on Damage Mechanics, Springer Verlag, Berlin, 1992.

R. Viswanathan: Damage Mechanisms and Life Assessment of High-Temperature Components, ASM International, Metals Park, Ohio, 1995.

H. L. Edwards, R.J.H. Wanhill: Fracture Mechanics, Edward Arnold Publ. Ltd., London, 1985.

D. Broek: The Practical Use of Fracture Mechanics, Kluwer Academic Publ., Dordrecht, 1988.

B. Dodd, Y. Bai: Ductile Fracture and Ductility: With Applications to Metallworking, Academic Press, Harcourt Brace Jovanovich Publishers, London, 1987.

S.S. Manson: Thermal Stress and Low-Cycle Fatigue, McGraw-Hill Book Company, New York, 1966.

A. Mendelson: Plasticity: Theory and Application, The MacMillan Company, New York, 1968.

W.F. Chen, D.J. Han: Plasticity for Structural Engineers, Springer Verlag, New York/Berlin, 1988.

R.W. Evans; B. Wilshire: Introduction to Creep, The Institute of Materials, Bourne Press Limited, Bournemouth, 1993.


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J.W. Dally, W.F. Riley: Experimental Stress Analysis, McGraw-Hill Inc., New York, 1991.

C.N. Reid: Deformation Geometry for Materials Scientists, Pergamon Press, Oxford, 1973.

P.E. Mix: Introduction to Nondestructive Testing: A TRAINING Guide, John Wiley & Sons Inc., New York, 1987.

R. Halmshaw: Non-Destructive Testing, Edward Arnold, London, 1991.

G.E. Dieter: Engineering Design: A Materials and Processing Approach, McGraw - Hill Book Company Inc., New York, 1987.

C. Matthews: IMechE Engineers Data Book, Professional Engineering Publishing Ltd., London, 2000.

M.F. Ashby: Materials Selection in Mechanical Design: Answers to Problems, Butterworth - Heinemann, Oxford, 1993.

M.F. Ashby: Materials Selection in Mechanical Design:Materials and Process Selection Cards, Butterworth - Heinemann, Oxford, 1993.

M.F. Ashby, D.R.H. Jones: Engineering Materials 1: An Introduction to Their Properties and Applications, International Series on Materials Science and Engineering, Volume 38, Pergamon

Press, Oxford, 1996.

M.F. Ashby, D.R.H. Jones: Engineering Materials 2: An Introduction to Microstructures, Processing and Design, International Series on Materials Science and Engineering, Volume 39,

Pergamon Press, Oxford, 1994.

M.F. Ashby: Materials Selection in Mechanical Design, Butterworth - Heinemann, Oxford, 1997.

L.A. Dobrzanski: Technical and Economical Issues of Materials Selection, Selesian technical University, Gliwice, 1997.

F.A.A. Crane, J.A. Charles: Selection and Use of Engineering Materials, Butterworths & Co. Ltd., London, 1984.

R.E. Smallman, R.J. Bishop: Metals and Materials: Science, Processes, Applications, Butterworth - Heinemann, Oxford, 1995.

E. Hornbogen: Werkstoffe, Springer Verlag, Berlin, 1994.

K.H. Decker: Maschinenelemente, Carl Hanser Verlag, Muenchen, 1975. (in German)

G.E. Totten, M.A.H. Howes: Steel Heat Treatment, Marcel Dekker, New York, 1997.

M. Oru, R. Sunulahpai: Lomovi i osnove mehanike loma, Univerzitet u Zenici, fakultet za metalurgiju i materijale, Zenica, 2009.

M. Jansen, J. Zuidema, R.J.H. Wanhill: Fracture Mechanics, Delft University Press, Delft, 2002.

T.V. Rajan, C.P. Sharma, A. Sharma: Heat Treatment Principles and Techniques, PHI Learning, New Delhi, 2011.

L.C.F. Cannale, R.A. Mesquita, G.E. Totten: Failure Analysis of Heat Treated Steel Components, ASM International, Materials Park, Ohio, 2008.

Allianz Handbook of Loss Prevention. Allianz Versicherungs AG, Berlin, 1987.

B. Joci: Steels and Cast Irons, BIO-TOP, Dobja Vas, 2008.

D. Mazumdar, J.W. Evans: Modeling of Steelmaking Processes, CRC Press, Taylor & Francis Group, Boca Raton, London, New York, 2010.

C. Matthews: A Guide to Presenting Technical Information, Professional Engineering Publishing Ltd., London, 2000.

P.A. Laplante: Technical Writing A Practical Guide for Engineers and Scientists, CRC Press, Taylor & Francis Group, Boca Raton, 2012.


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JOURNALS

Engineering Fracture Mechanics http://www.elsevier.com/inca/publications/store/3/2/2

ISSN 0928-1045

Engineering Failure Analysis http://www.elsevier.com/locate/engfailanal

ISSN 1350-6307

Practical Failure Analysis http://www.asm-intl.org/journals

ISSN 1529-8159

International Journal of Damage Mechanics http://www.techpub.com

ISSN 1056-7895

Acta Materialia http:// www.elsevier.com/inca/publications/store/2/2/1

ISSN 1359-6454

Materials Science and Technology http://www.materials.org.uk

ISSN

Journal of Computer-Aided Materials Design http://www.wkap.nl/journals/jcd

ISSN 0928-1045

Journal of Materials Processing Technology http:// www.elsevier.com/inca/publications/store/5/0/5/6/5/6

ISSN 0924-0136

Computational Materials Science http:// www.elsevier.com/inca/publications/store/5/2/3/4/1/2

ISSN 0927-0256

Tehnika dijagnostika (Technical Diagnostics) http:// www.tehnickadijagnostika.com

ISSN 1451-1975

Integritet i vek konstrukcija (Structural Integrity and Life) http:// www.divk.org.rs/ivk

ISSN 1451-3749

Metalurgija (Metallurgy) http://public.carnet.hr/metalzrg

ISSN 0543-5846

Failure Analysis Master Course V1

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