Non destructive testing of materials

PRESENTED BY
MOHAMMED ABDUL SHAFEEQ
(M.TECH)

NEED AND DEFINITION
• An industrial product is designed to perform a certain
function
• The user buys it with an expectation that it will perform
the assigned function well and it gives a trouble-free
service for a reasonable period of time
• The level of guarantee or certainity with which a trouble-
free service can be provided by any product may be
termed as its degree of reliability
• The reliability of a machine having a number of
components depends upon the reliability factors of all the
individual components

Continued……
 Reliability comes through improving the quality or quality
level of the products
 A good quality product can therefore be termed as one
which performs it’s assigned function for a reasonable
length of time
 The products which fails to meet this criterion ,their
breakdown occurs unpredictably and earlier than a
specified time called as bad quality products
 The improvement of product quality to bring it to a
reasonable quality level is important in many ways
 It leads to increase in reliability of products and the
safety of machines and equipment

Continued………
 It results in bringing economic returns to the
manufacturer by increasing his production,reducing
scrap levels
 It leads him to enhance his reputation as a producer of
quality goods and hence boosting his sales
 There is therefore a need to have methods by which the
defects in products can be determined without effecting
their serviceability
 A wide variety of test schemes exist,some destructive and
some non-destructive
 Strictly speaking,Non-destructive testing has no clearly
defined boundaries

Continued……
 According to ASTM,Non-destructive testing is the development
and applications of technical methods to examine the material
of components
 That should be in the way such that it do not impair future
usefulness,serviceability in the process of detecting and
locating the discontinuities
 Non-destructive testing plays an important role in the quality
control not only of the finished products,but also of the half
finished products and raw materials
 Non-destructive testing(NDT) is the process of
inspecting,testing materials for discontinuities with out
destroying the serviceability of the part or system
 In other words,when the inspection or test is completed the
part can still be used

Continued……
The destructive tests are often used to determine the
physical properties of materials such as impact
resistance,ductility, ultimate tensile strength…etc
 The non-destructive tests are often used to
determine molecular properties such as
discontinuities,material characteristics..etc

TYPES OF NDT
The most important NDT methods are given below
1.Visual and optical testing
2.Liquid penetrant testing
3.Ultrasonic testing
4.Magnetic particle inspection
5.Eddy current testing
6.Radio graphy
7.Leak testing

• For any product that we want to inspect through NDT, its
internal region is divided into three types, namely
1.Surface region
2.Sub-surface region
3.Interior region
It is shown in the figure below

• The type of test is to be performed is decided on the
basis of the location of the defect
• For surface opening defects, Liquid penetrate test
(LPT) is most commonly used
• For surface defects,Magnetic particle test(MPT)
Ultrasonic test(UT),Radiography test(RT),Eddy
current test(ECT) are used
• For sub-surface defects,MPT,UT,RT,ECT are used
• For interior defects,UT,RT are used

CATEGORIES OF NDT
All the major NDT methods are placed into two
categories,they are
1.ACTIVE TECHNIQUES
2.PASSIVE TECHNIQUES

Continued…..
The active techniques are those where a test medium
is applied to the test specimen and a response is
expected if a flaw is present
The response is then detected by some means and
recorded
Magnetic particle testing,ultra sonic testing, and
radiography fall into this category

Continued…..
Passive techniques are those that monitor the item
during either a typical load environment or a proof
cycle and attempt to determine the presence of defect
This is through some reaction of a specimen
Acoustic emission,Noise analysis,leak testing,visual
examination,and some residual magnetic techniques
are in this classification

VISUAL AND OPTICAL
TESTING(VT)
Visual inspection involves using an inspector’s eyes
to look for defects
 The inspector may also use special tools such as
magnifying glasses,mirrors,borescopes to gain access
and more closely inspect the subject area
 Visual examiners follow procedures that range from
simple to very complex

LIQUID PENETRANT
TESTING
Test objects are coated with visible or flouroscent dye
solution
 Excess dye is then removed from the surface,and a
developer is applied
 The developer acts as a blotter,drawing trapped
penetrant out of imperfections open to the surface
 With visible dyes,colour contrasts between the
penetrant and developer make “bleed out” easy to see
 With flouroscent dyes,Ultra violet light is used to
make the bleedout flouroscence brightly,thus
allowing imperfections to be readily seen

Basic processing steps of
Liquid penetrate testing
1.SURFACE PREPARATION:
The surface must be free of oil,grease,water or other
contaminents
The sample may also require etching if mechanical
operations such as machining,sanding have been
performed
These and other mechanical operations can have
metal over the flaw opening and prevent the
penetrant from entering

Continued………
2.PENETRANT APPLICATION:
• Once the surface has been thoroughly cleaned and
dried,the penetrant material is applied by
spraying,brushing,or immersing the part in a
penetrant bath

Continued……..
3.PENETRANT DWELL:
• The penetrant is left on the surface for a sufficient time to
allow as much penetrant as possible to be drawn from or
to seep into a defect
• Penetrant dwell time is the total time that the penetrant is
in contact with the part surface
• The times vary depending upon the application,penetrant
materials used,the material,the form of the material being
inspected,type of defect being inspected for
• Minimum dwell time typically ranges from 5 to 60
minutes
• Generally,there is no harm in using a longer penetrant
dwell time as long as the penetrant is not allowed to dry

Continued…….
4.EXCESS PENETRANT REMOVAL:
• This is the most delicate part of the inspection procedure
• Because the excess penetrant must be removed from the
surface of the sample while removing as little penetrant
as possible from defects
• Depending on the penetrant system used,this step may
involve cleaning with a solvent,direct rinsing with water
or first treating the part with an emulsifier and then
rinsing with water

Continued…….
5.DEVELOPER APPLICATION:
A thin layer of developer is then applied to the
sample to draw penetrant trapped in flaws back to
the surface where it will be visible
Developers come in a variety of forms that may be
applied by dusting(dry powdered),dipping or
spraying(wet developers)

Continued………
6.INDICATION DEVELOPMENT:
• The developer is allowed to stand on the part surface
for a period of time sufficient to permit the extraction
of the trapped penetrant out of any surface flaws
• This development time is usually a minimum of 10
minutes
• Significantly,longer times may be necessary for tight
cracks

Continued……..
7.INSPECTION:
• Inspection is then performed under appropriate
lighting to detect indications from any flaws which
may be present
8.CLEAN SURFACE:
• The final step in this process is to thoroughly clean
the part surface to remove the developer from the
parts that were found to be acceptable

ADVANTAGES OF LIQUID
PENETRATE TESTING:
• This method is highly sensitive to the small surface
discontinuities
• This method has few material limitations i.e. almost all type
of materials can be inspected
• Large areas and large volumes of parts can be inspected
rapidly and at low cost
• Parts with complex geometric shapes are routinely inspected
• Indications are produced directly on the surface of the part
and constitute a visual representation of flaw
• Aerosol spray cans make penetrant materials very portable
• Penetrant materials and associated equipment are relatively
in expensive.

DISADVANTAGES OF LIQUID
PENETRATE TESTING
Only surface breaking defects can be detected
Only materials with a relatively non-porous surface
can be inspected
Precleaning is critical since contaminants can mask
defects
Must have direct access to the surface being
inspected
Surface finish and roughness can affect inspection
sensitivity
Post cleaning of tested materials is required
Chemical handling and proper disposal is required

ULTRA SONIC TESTING
Ultra sonic testing uses high frequency sound energy
to conduct examinations and make measurements
The most commonly used ultrasonic testing
technique is pulse echo,where sound is introduced
into a test object
The reflections(echoes) are returned to a receiver
from internal imperfections

• A typical UT inspection system consists of several
functional units,such as pulse/receiver, transducer,
and display devices
• A pulser/receiver is an electronic device that can
produce high voltage electrical pulses
• Driven by the pulser,the transducer generates high
frequency ultra sonic energy
• The sound energy is introduced and propogates
through the materials in the form of waves
• When there is a discontinuity (such as crack) in the
wave path,part of energy will be reflected back from
the flaw surface

Continued…….
• The reflected wave signal is transformed into an
electrical signal by the transducer and is displayed
on the screen
• The reflected signal strength is displayed versus the
time from signal generation to when an echo was
received
• Signal travel time can be directly related to the
distance that the signal travelled
• From the signal, information about the reflector
location,size,orientation and other features can
sometimes be gained

ADVANTAGES OF UT
• It is sensitive to both surface and sub-surface
discontinuities
• The depth of penetration for flaw detection or
measurement is superior
• Only single-sided access is needed
• Minimal part preparation is required
• Instantaneous results
• It has other uses,such as thickness measurement,in
addition to flaw detection

DISADVANTAGES OF UT
• Surface must be accessible to transmit ultrasound
• Skill and training is more extensive than with some
other methods
• Materials that are rough,irregular in shape,very small
exceptionally thin,or not homogeneous are difficult to
inspect
• Linear defects oriented parallel to the sound beam
may go undetected
• Reference standards are required for both equipment
calibration and the characterization of flaws

EDDY CURRENT INSPECTION
(ECI)
• Electrical currents are generated in a conductive
material by an induced alternating magnetic field
• The electrical currents are called as Eddy currents
because they flow in circles at and just below the
surface of the material
• Interruptions in the flow of Eddy currents,caused by
imperfections,dimensional changes,or changes in
material’s conductive and permeability properties.
• It can be detected by proper equipment

Continued……..
BASIC PRINCIPLE:
• Eddy currents are created through a process called
electro magnetic induction
• When an alternating current is applied to the
conductor,such as copper wire,a magnetic field
develops in and around the conductor
• This magnetic field expands as the alternating
current rises to maximum and collapses as the
current is reduced to zero

• If another electrical conductor is brought into the
close proximity to this changing magnetic
field,current will be induced in this second conductor
• Eddy currents are induced electrical currents that
flow in a circular path

ADVANTAGES OF ECI:
• Sensitive to small cracks and other defects
• Detects surface and near surface defects
• Inspection gives immediate results
• Equipment is very portable
• Method can be used for much more than flaw
detection
• Minimum part preparation is required
• Inspects complex shapes and sizes of conductive
materials

DISADVANTAGES OF ECI:
• Only conductive materials can be inspected
• Skill and training required is more extensive than the
other techniques
• Surface finish and roughness may interfere
• Reference standards needed for setup
• Depth of penetration is limited

RADIOGRAPHY(RT)
Radiography involves the use of penetrating gamma
or X-radiation to examine parts and products for
imperfections
An X-ray generator or radio active isotope is used as
a source of radiation
Radiation is directed through a part and onto film or
other imaging media
The resulting shadowgraph shows the dimensional
features of the part
Possible imperfections are indicated as density
changes on the film in the same manner as medical
X-ray shows the broken bones

Continued……
Defective areas such as porosity,cracks,weld
undercut,usually show up darker on the film except
for defects such as excess weld metal,spatter..etc
ADVANTAGES:
• Detects surface and sub-surface defects
• Can be used on a wide variety of materials
• Provides permanent record of the inspection
DISADVANTAGES:
• Safety precautions are required for sage use of
radiation
• Access to both sides of the specimen required
• Orientation of the sample is critical
• Bulky and expensive machinery is required

LEAK TESTING(LT)
• Several techniques are used to detect and locate
leaks in pressure contaminant parts,pressure vessels
and structures
Leaks can be detected by using
• Electronic listening devices
• Pressure gauge measurements
• Liquid and gas penetrant techniques
• A simple soap bubble test

MAGNETIC PARTICLE
INSPECTION(MPI)
• Magnetic particle inspection is fast and relatively
easy to apply and part surface preparation is not as
critical as other NDT methods
• These characteristics make MPI one of the most
widely utilized non-destructive testing methods
• This method is used to inspect a variety of products
such as castings,forgings,and weldments
• Many different industries use magnetic particle
inspection for discovering surface and sub-surface
discontinuities
• Some examples of the industries use this technique
are structural steel,automotive,petrochemical,power
generation,and aerospace industries

HISTORY OF MPI:
Magnetism is the ability of matter to attract other
matter to itself
The ancient greeks were the first to discover this
phenomenon in a mineral they named magnetite.
Later on Bergmann, Becquerel and faraday
discovered that all matter including liquids and gases
were effected by magnetism
The earliest known use of Magnetism to inspect an
object took place as early as 1868
Carron Barrels were checked for defects by
magnetizing the barrel then sliding a magnetic
compass along the barrel’s length

Continued……..
• These early inspectors were able to locate flaws in the
barrels by monitoring the needle of the compass
• This was a form of non-destructive-testing but the
term was not commonly used untill sometime after
world war-1
• In the early 1920’s,William hoke realized that
magnetic particles(coloured metal shavings)could be
used with magnetism as a means of locating defects
• Hoke discovered that a surface or sub-surface flaw in
a magnetized material caused the magnetic field to
distort and extend beyond the part
• This discovery was brought to his attention in the
machine shop

Continued……..
 He noticed that the metallic grindings from hard steel
parts(held by a magnetic chuck while being ground) formed
patterns on the face of the parts
 They corresponded to the cracks in the surface
 Applying a fine ferro magnetic powder to the parts caused a
build up of powder over flaws and formed a visible indication
 In the early 1930’s,magnetic particle inspection was quickly
replacing the oil-and-whiting method(an early form of the
liquid penetrant inspection)
 It is the method of choice by the railroad industry to inspect
steam engine boilers,wheels,axles and tracks
 Today,the MPI inspection method is used extensively to check
for flaws in a large variety of manufactured materials and
components

BASIC CONCEPTS OF
MAGNETISM
MAGNETIC FIELD: It simply describes a volume of
space where there is a change in energy within that
volume.This change can be detected and measured
MAGNETIC POLE:The location where a magnetic
field can be detected exiting or entering a material is
called a magnetic pole
POLE:The point in a bar magnet where the maximum
magnetic force exists is called pole
DIPOLE:The existence of two unlike poles in a single
material is called dipole
NORTH POLE:The pole in a bar magnet where the
lines of force exits is called north pole

Continued……..
SOUTH POLE:The pole in a bar magnet where the
lines of force enters is called south pole
MAGNETIC FLUX:Magnetic flux is the imaginary
lines of force associated with the defined area.It’s
units are weber
MAGNETIC FLUX DENSITY:The number of magnetic
lines of force cutting through a plane of a given area
at a right angle is known as the magnetic flux
density(B). It has tesla as it’s unit
MAGNETIC PERMEABILITY:The degree of magneti-
zation of a substance in a given magnetic field
It is defined as the ratio of magnetic flux density(B)
to magnetic field strength(H)

Continued…….
It is defined in other words as the ability of the
material to allow the magnetic line of force to pass
through it
MAGNETIC SUSCEPTIBILITY:It is a dimensionless
proportionality constant that indicates the degree of
magnetization of a material in response to applied
magnetic field.
It is denoted by “X”
PROPERTIES OF MAGNETIC LINES OF FORCE:
• The magnetic lines seek the path of least resistance
between opposite magnetic poles.In a single bar
magnet they attempt to form closed loop from pole to
pole

Continued…….
They never cross one another
They all have the same strength
Their density decreases(they spread out)when they
move from an area of higher permeability to an area
of lower permeability
Their density decreases with increasing distance from
the poles
They are considered to have direction as if
flowing,though no actual movement occurs.they flow
from the south pole to the north pole within the
material and north pole to south pole in air

TYPES OF MAGNETIC
MATERIALS
Magnetic materials are divided into three types based
up on their behaviour in the magnetic field,they are
Dia magnetic material
Para magnetic material
Ferro magnetic material
DIA MAGNETIC MATERIAL:
• Materials have a weak and negative susceptibility to
magnetic fields
• They are slightly repelled by a magnetic field and
does not retain the magnetic properties when the
external field is removed
• Examples:copper,silver,gold

Continued…….
PARAMAGNETIC MATERIALS:
• Materials have a small and positive susceptibility to
magnetic fields
• These materials are slightly attracted by a magnetic
field
• These materials does not retain magnetic properties
when the external field is removed
• Examples:magnesium,molybdenum,lithium,..etc
FERROMAGNETIC MATERIALS:
• Materials have a large and positive susceptibility to
an external magnetic field
• They exhibit a strong attraction to magnetic fields
and are able to retain their magnetic properties after
the external field is removed

Continued……….
 Ferro magnetic materials get their magnetic
properties not only because their atoms carry a
magnetic moment,but also because the material is
made up of small regions known as magnetic
domains
 In non-magnetized state,the domains are nearly
randomly organized and in magnetized state,the
domains are alligned as shown in figure
Example:iron,cobalt,nickel

PRINCIPLE INVOLVED UNDER
ELECTRO MAGNETIC
MAGNETIZATION:
Electric field is always accompanied with magnetic
field
The flemings rules tell how the electric field and
magnetic field accompanied with each other
Fleming gives two rules—1.Fleming’s left hand rule
2.Fleming’s right hand rule
FLEMING’S LEFT HAND RULE:
• It is used for electric motors
• The left hand is held with the thumb,index finger,and
middle finger mutually at right angles
• The fore finger represents the direction of the
magnetic field(north to south)

Continued……….
The middle finger represents the direction of the
conventional current(from positive to negative)
The thumb represents the direction of force or
resultant motion

Continued……..
FLEMING’S RIGHT HAND RULE:
• It is used for generators
• It shows the direction of induced current flow when a
conductor moves in magnetic field
• The right hand is held with the thumb,fore
finger,middle finger mutually perpendicular to each
other
• The thumb represents the direction of motion of the
conductor
• The fore finger represents the direction of magnetic
field (north to south)
• The middle finger represents the direction of induced
current(positive to negative)

Continued………
Whenever a current carrying conductor comes under
magnetic field naturally,there will be force acting on
the conductor,In this situation,the relationship
between magnetic field,current,force will be explained
by fleming’s left hand rule
Whenever the current carrying conductor is forcefully
brought under magnetic field,the relationship
between magnetic field,induced current,force will be
given by fleming’s right hand rule

HYSTERESIS LOOP
By studying this hysteresis loop,we can learn about
the magnetic properties of the material
This loop shows relationship between the induced
magnetic flux density(B)and the magnetizing force(H)
The loop is generated by measuring the magnetic flux
(B) of a ferromagnetic material while the magnetizing
force(H) is changed

Continued………
RETENTIVITY:It is a material’s ability to retain a
certain amount of residual magnetic field when the
magnetizing force is removed after achieving
saturation
COERCIVE FORCE:The amount of reverse magnetic
field which must be applied to a magnetic material to
make the magnetic flux return to zero
Relative to the other material,the materials with
the wide hysteresis loop has:
• Lower permeability
• Higher retentivity
• Higher coercivity
• Higher reluctance
• Higher residual magnetism

Continued……
The material with the narrower loop has:
• Higher permeability
• Lower retentivity
• Lower coercivity
• Lower reluctance
• Lower residual magnetism
• In magnetic particle inspection,the level of residual
magnetism is important
• Residual magnetic fields are effected by the
permeability, which can be related to the carbon
content and alloying of the material
• A component with high carbon content will have low
permeability and will retain more magnetic flux than
a material with low carbon content

BASIC PRINCIPLE OF MPI
 The main principle behind this magnetic particle
inspection is MAGNETIC FLUX LEAKAGE
 If we break the bar magnet into the centre will result
two bar magnets with north and south poles on each
end of the magnets
 If the magnet is just cracked but not broken into two
pieces,a north and south pole will form at each edge
of the crack
 The magnetic field exits the north pole and re-enters
the south pole.
 The magnetic fields spreads out when it encounter
the small air gap created by the crack because the air
cannot support as much magnetic field per unit
volume as magnet can

Continued…….
When the field spreads out,it appears to leak out of
the material and,thus,it is called a flux leakage field
If iron particles are sprinkled on a cracked
magnet,the particles will be attracted and cluster not
only at the poles at the ends of the magnet but also
at the poles at the edges of the crack
This cluster of particles is much easier to see than
the actual crack and this is the basis for MPI.

PROCESS TO CONDUCT MPI:
The entire process is carried out in 8 steps,they are:
1.Surface preparation
2.Surface cleaning
3.Magnetize the test specimen
4.Magnetic particle application
5.Excess magnetic particle removal
6.Indication,identification and marking
7.De-magnetization
8.Report writing and evaluation

Continued……
 Surface preparation: Surface should be prepared in
such a way it should be useful for testing by this
method.Grinding operation should be done to obtain
the surface neatly
 Surface cleaning: As in liquid penetration
test,surface should be cleaned neatly such that no
impurities should be present on the surface
Solvent remover should be used for cleaning the
surface
• Magnetization of specimen: Two general types of
magnetic fields are introduced into the specimen.they
are:
1.Longitudinal magnetization
2.Circular magnetization

Continued……..
A longitudinal magnetic field has magnetic lines of
force that run parallel to the long axis of the part
A Circular magnetic field has magnetic lines of force
that run circumferentially around the perimeter of
the part
Methods of magnetization:There are two methods
of magnetization, they are
1.Direct magnetization
2.Indirect magnetization
Direct magnetization:Current is directly passed
through the component.This is done through
i)Head shot method
ii)Prod method

Continued……
Indirect magnetization: It is accomplished by using a
strong external magnetic field to establish a magnetic
field within the component.This is done through
1.Electromagnetic yoke method
2.Central conductor method
HEAD SHOT METHOD PROD METHOD

Continued…..
YOKE METHOD CENTRAL CONDUCTOR
METHOD

Continued…….
MAGNETIC PARTICLE APPLICATION:
Two types of magnetic particles are applied, they are
1.Dry particles
2.Wet particles
• Dry particles are generally used for inspection on
rough surfaces
• Wet inspections are generally considered as best for
detecting very small discontinuities on smooth
surfaces
• Black contrast and white contrasts are used for
identifying discontinuities in wet particle method

Continued……
DRY PARTICLES
WET PARTICLES

Continued…….
EXCESS PARTICLE REMOVAL: Excess particles
should be removed for clear identification of defects
INDICATION,IDENTIFICATION AND MARKING:
1.The direction of magnetic field is identified by using
pie guage
2.Field indicator,hall-effect meter are used to measure
the strength of the magnetic field
3.Defects are identified and they are marked
FIELD INDICATOR

Continued…..
PIE GUAGE
HALL EFFECT METER

Continued……
• DEMAGNETIZATION:De-magnetization is commonly
done in two ways
1.Hammering
2.Reverse magnetization
• REPORT WRITING AND EVALUATION:
A report is made based on the results obtained after
conducting the test.
Based on that report, the product will be judged whether it
will be useful for future use or not
This is the entire process of MPI

ADVANTAGES OF MPI:
Easy to handle equipment
Longitudinal magnetization machines are portable
It is not limited by the size and shape of the
specimen being tested.small tanks to large cranes
can be inspected using this method
Cost is inexpensive when compared to UT and RT
DISADVANTAGES:
• It can be applied to only ferro-magnetic materials
• More consumption of electricity
• We can identify only surface and sub-surface defects
• Safety is needed

ANALYSIS OF MY MPT TEST
 WORK PIECE:Work piece is the weldment of two
mild steel plates of dimensions 250mm X 120mm X
12 mm each.
 Weldment is a V-butt joint joined with solid metal arc
welding process
MY WORKPIECE

Continued…….
• METHOD OF MAGNETIZATION:The method I used
is Electromagnetic yoke method with direct current
• Reason to adopt this method is yoke is portable and
is applicable here as a laboratory purpose
• Prod machine serves the same purpose but with the
high voltage of 2000V which can be used only for the
inspection of huge components in industry
• As the weight of work piece is 7 kgs, AC cannot be
used because AC can bear only upto 4.5 kgs where
as DC can hold 18 kgs

Continued……..
 CALIBRATION:Calibration is performed in order to
check the performance of the electromagnetic yoke
machine.
 It is conducted on the ASTM test block which
consists of holes at standard distances and depths
 Correct indication of defects in the block is the
indication that the electromagnetic yoke is in perfect
condition
 The calibration is done….the yoke used here is in
perfect condition

Continued…..
• YOKE CALIBRATION AND LIMITATIONS:
• LIFTING CAPACITY:
FOR AC-4.5 KG
FOR DC-18.1KG
• SENSITIVITY CHECK:
AC-1MM
DC-5MM
• Can check defects upto depth of 6 mm
theoretically….

WELD DEFECTS FOUND USING DRY MAGNETIC PARTICLES
UNDERCUT

CONCLUSION:
• SPATTERS: Occurred due to disturbance in the
molten weld pool during the transfer of wire into the
weld,typically caused by voltage being too low or
amperage being too high
• UNDERCUT: Occurred because of melting of parent
metal because of high arc during welding and so the
fusion of weld is improper at the toe of the weld
• CRACKS:The crack here in the weld is found
because of difference in travel speed or
current.Also,pressure applied on electrode during
welding may be the cause for the formation of crack

Continued……
EVALUATION:
• Sputters can be removed by careful grinding on the
surface but undercut and crack here obtained cannot
be rectified
• If it is in the industry as the components are huge
castings they are grounded to the depth of defect and
the crack is filled by welding
• Applications of high stresses results in more
cracks.More the number of defects,ability of the
material to with stand loads is less
• In the weld portion,if cracks or undercuts are found,
then the component is not considered for further use

REFERENCES:
 TYPES OF WELD:
http://mechanicalinventions.blogspot.in/2014/10/differ
ent-types-of-welding-defects.html
 TYPES OF JOINTS:
http://www.ateliersbg.com/news/the-5-types-of-basic-
welding- joints.aspx
 TYPES OF WELDING:
http://engineeringhut.blogspot.in/2010/11/welding-
and-its-classification.html
 BASICS OF NDT: https://www.nde-
ed.org/EducationResources/CommunityCollege/MagPa
rticle/TestingPractices/Dry%20Particle.htm
 MPT:
http://mech.vub.ac.be/teaching/info/Damage_testing_
prevention_and_detection_in_aeronautics/PDF/magne
tic.pdf

Non destructive testing of materials

Non destructive testing of materials

More Related Content

What's hot (20)

Similar to Non destructive testing of materials (20)

Recently uploaded (20)

Non destructive testing of materials