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)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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)
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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)
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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Thermography Case study: House
220,0C
1000,0C
400
600
800
1000
Thermography Case study: Inductive heating
Thermography Case study: Steel slab heattreatment
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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.
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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.)
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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.
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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.
B. Kosec, A. Nagode, G. Kosec: FAILURE ANALYSIS (Master Course)
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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
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