UT _ Ultrasonic Testing

MET312 NON
MET312 NON-
-DESTRUCTIVE TESTING
DESTRUCTIVE TESTING
MODULE
MODULE-
-4
4 –
– ULTRASONIC TESTING
ULTRASONIC TESTING
Compiled by : SUKESH O P/ APME/JECC 1
MODULE
MODULE-
-4
4 –
– ULTRASONIC TESTING
ULTRASONIC TESTING
Sukesh O P
Assistant Professor
Department of Mechanical Engineering,
Jyothi Engineering College, Cheruthuruthy
9633103837 II sukeshop@jecc.ac.in

ME357 Non-Destructive Testing
2
Introduction to NDT
Introduction to NDT-
- Visual Inspection
Visual Inspection-
- Liquid
Liquid
Penetrant Inspection
Penetrant Inspection-
- Magnetic
Magnetic Particle
Particle
Inspection
Inspection-
- Ultrasonic Testing
Ultrasonic Testing-
-
Compiled by : SUKESH O P/ APME/JECC
Inspection
Inspection-
- Ultrasonic Testing
Ultrasonic Testing-
-
Radiography Testing
Radiography Testing-
- Eddy Current Testing.
Eddy Current Testing.

Module-4 Syllabus
3
 Ultrasonic Testing: Basic principles of sound propagation,
types of sound waves, Principle of UT-methods of UT, their
advantages and limitations- Piezoelectric Material, Various
types of transducers/probe-Calibration methods, contact
testing and immersion testing, normal beam and straight
beam testing, angle beam testing, dual crystal probe,
ultrasonic testing techniques resonance testing, through
ultrasonic testing techniques resonance testing, through
transmission technique, pulse echo testing technique,
instruments used UT, accessories such as transducers, types,
frequencies, and sizes commonly used. Reference of standard
blocks-technique for normal beam inspection-flaw
characterization technique, defects in welded products by UT-
Thickness determination by ultrasonic method;- Study of A, B
and C scan presentations-Time of Flight Diffraction (TOFD)

MODULE
MODULE-
-4
4
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 The three types of sound are:

 Infrasonic
Infrasonic:
: It is a sound with a frequency of less than
20Hz. Elephants use Infrasonic sounds to interact
with herds hundreds of km away.
with herds hundreds of km away.

 Sonic
Sonic:
: It is a sound with the frequency between 20
to 20,000Hz. ...

 Ultrasonic
Ultrasonic:
: It is a sound with a frequency more than
20,000Hz.

Infrasonic sound
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 Having or relating to a frequency below the
audibility range of the human ear.
 utilizing or produced by infrasonic waves or
vibrations.
vibrations.
 Infrasound, is a low-frequency sound less than
20Hz. Animals that can communicate using infrasonic
sounds are; Rhinos, hippos, elephants, whales,
octopus, pigeons, squid, cuttlefish, cod, Guinea
fowl.

Ultrasonic sound
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 The definition of ultrasonic, also known as
ultrasound, is sound waves that have a higher
frequency than the human ear can hear. An
example of ultrasonic is an ultrasound image of an
unborn baby.
unborn baby.
 Bats, Insects like beetles, moths, praying mantis,
dolphins, dogs, frogs and toads, etc. communicate
using ultrasonic hearing.

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INTRODUCTION
INTRODUCTION
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 Ultrasonic testing(UT) which is applicable to most
materials, metallic or non-metallic.
 Ultrasonic testing uses high frequency sound energy to
conduct examinations and make measurements.
 Ultrasonic examinations can be conducted on a wide
Frequencies from 1-10 Mega Hertz(MHz)
are typically used.
 Ultrasonic examinations can be conducted on a wide
variety of material forms including castings, forgings,
welds, and composites.
 By this method, surface and internal discontinuities such
as laps, seams, voids, cracks, blow holes, inclusions and
lack of bond can be accurately evaluated from one
side.

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Basic Principle of UT
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 In ultrasonic testing, ultrasound transducer connected to
a diagnostic machine is passed over the object being
inspected.
 The transducer is typically separated from the test
object by a couplant (such as oil) or by water, as in
object by a couplant (such as oil) or by water, as in
immersion testing. However, when ultrasonic testing is
conducted with an Electromagnetic Acoustic Transducer
(EMAT) the use of couplant is not required.
 There are two methods of receiving the ultrasound
waveform: reflection and attenuation

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SOUND
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Wavelength :
 The distance required to complete a cycle
– Measured in Meter or mm
Frequency :
The number of cycles per unit time
 The number of cycles per unit time
– Measured in Hertz (Hz) or Cycles per second (cps)
Velocity :
 How quick the sound travels
 Distance per unit time
– Measured in meter / second (m / sec)

Basic Principles of Sound
Sound is produced by a vibrating body and travels in the form
of a wave.
Sound waves travel through materials by vibrating the
particles that make up the material.
The pitch of the sound
is determined by the
is determined by the
frequency of the wave
(vibrations or cycles
completed in a certain
period of time).
Ultrasound is sound
with a pitch too high
to be detected by the
human ear.
Compiled by : SUKESH O P/
APME/JECC
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Properties of a sound wave
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 Sound cannot travel in vacuum
 Sound energy to be transmitted / transferred from
one particle to another

Sound waves
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 All sound waves, whether audible or ultrasonic, are
mechanical vibrations involving movement of the
medium in which they are travelling.
 A sound wave may be transmitted through any
 A sound wave may be transmitted through any
material which behaves in an elastic manner.
 Longitudinal waves
 Transverse or shear waves
 Surface or Rayleigh waves

Ultrasonic waves
 Ultrasonic waves are very similar to light waves
in that they can be reflected, refracted, and
focused.
 Reflection and refraction occurs when sound
waves interact with interfaces of differing
acoustic properties.
 In solid materials, the vibrational energy can be
split into different wave modes when the wave
encounters an interface at an angle other than
90 degrees.
 Ultrasonic reflections from the presence of
discontinuities or geometric features enables
detection and location.
 The velocity of sound in a given material is
constant and can only be altered by a change in
the mode of energy. Compiled by : SUKESH O P/
APME/JECC
23

Longitudinal waves
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 Longitudinal waves are waves in which the
displacement of the medium is in the same direction
as, or the opposite direction to, the direction of
propagation of the wave.
Mechanical longitudinal waves are also
 Mechanical longitudinal waves are also
called compressional or compression waves, because
they produce compression and rarefaction when
traveling through a medium, and pressure waves,
because they produce increases and decreases in
pressure.

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Transverse or shear wave
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 A transverse wave is a moving wave that consists of
oscillations occurring perpendicular (right angled) to the
direction of energy transfer (or the propagation of the
wave).
If a transverse wave is moving in the positive x-
 If a transverse wave is moving in the positive x-
direction, its oscillations are in up and down directions
that lie in the y–z plane.
 Light is an example of a transverse wave, while sound is
a longitudinal wave. A ripple in a pond and a wave on
a string are easily visualized as transverse waves.

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Surface or Rayleigh waves
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 This type of waves can travel only along surface
bounded on one side by strong elastic forces of the
solid and on the other by nearly nonexistent elastic
forces between gas molecules.
 Surface waves therefore are essentially nonexistent
in a solid immersed in liquid, unless the liquid covers
the solid surface only as a very thin layer.

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Plate or Lamp waves
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VELOCITY
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 The velocity of sound in a particular material is CONSTANT
 It is the product of DENSITY and ELASTICITY of the material
 It will NOT change if frequency changes
 Only the wavelength changes
 Examples:
 Examples:
 V Compression in steel : 5960 m/s
 V Compression in water : 1470 m/s
 V Compression in air : 330 m/s

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FREQUENCY
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 Generally the choice of test frequency depends
upon two factors : the
the minimum
minimum size
size of
of defect,
defect, which
which
is
is to
to be
be detected
detected and
and the
the medium
medium in
in which
which such
such a
a
defect
defect is
is situated
situated.
.

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Reflection
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 Light can bend and move through the material,
which is called refraction. Or, light can bounce off
the material, which is called reflection.
 When sound travels in a given medium, it strikes the
 When sound travels in a given medium, it strikes the
surface of another medium and bounces back in
some other direction, this phenomenon
is called the reflection of sound. The waves
are called the incident and reflected sound waves.

Divergence
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 A term used to describe the spreading of ultrasonic
waves beyond the near field. It is a function of the
transducer diameter and wave length in the
medium.
 Divergence angle, angle within the far field between
the beam axis and the beam edge at which the
amplitude has fallen by a defined level

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 Scattering : it is the reflection of sound beam from
its original direction of propagation.
 Absorption : it is conversion of sound energy from
one form to some another form.
one form to some another form.

Attenuation of sound waves
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 It is a combined effect of scattering and absorption.
Which states that when a sound beam travels
through any medium, its intensity gradually reduces
due to scattering and absorption.
 Attenaution defines the decay rate of propagated
sound wave.

TEST TECHNIQUES
TEST TECHNIQUES
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 Ultrasonic testing is a very versatile inspection method, and
inspections can be accomplished in a number of different ways.
 Ultrasonic inspection techniques are commonly divided into three
primary classifications.
Pulse-echo and Through Transmission
 Pulse-echo and Through Transmission
- (Relates to whether reflected or transmitted energy is used)
 Normal Beam and Angle Beam
- (Relates to the angle that the sound energy enters the test article)
 Contact and Immersion
- (Relates to the method of coupling the transducer to the test article)

Pulse
Pulse Echo
Echo Method
Method
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 This is the method most commonly utilized in the
ultrasonic testing of materials. The transmitter and
receiver probes are on the same side of the specimen
and the presence of a defect is indicated by the
reception of an echo before that of the back wall echo.
reception of an echo before that of the back wall echo.
 The CRT screen is calibrated to show the separation in
distance between the time of arrival of a defect echo
as against that of the back wall echo of the specimen,
therefore, the location of a defect can be assessed
accurately.

Pulse Echo Technique
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Pulse Echo Technique
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 Single probe sends and receives sound
 Gives an indication of defect depth and dimensions
 Not fail safe

Through Transmission Method
Through Transmission Method
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 In this method two ultrasonic probes are used.
 One is the transmitter probe and the other is the
receiver probe.

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 In this method the presence of an internal defect is
indicated by a reduction in signal amplitude, or in
the case of gross defects, complete loss of the
transmitted signal.

Through transmission testing
Through transmission signal
1 1
T R
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0 2 4 6 8 10
2 2
T R
Flaw

Through Transmission Technique
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Through Transmission Technique
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 Advantages
 Less attenuation
 No probe ringing
 No dead zone
 Orientation does not matter
Orientation does not matter
 Disadvantages
 Defect not located
 Defect can’t be identified
 Vertical defects don’t show
 Must be automated
 Need access to both surfaces

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Resonance Method
Resonance Method
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 A condition of resonance exists whenever the
thickness of a material equals half the wavelength
of sound or any multiple thereof in that material.
 Control of wavelength in ultrasonics is achieved by
 Control of wavelength in ultrasonics is achieved by
control of frequency.

Resonance Method
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 Knowing the resonance or fundamental frequency f
and velocity V of ultrasound in the specimen the
thickness ‘t’ of the specimen under test can be
calculated from the equation : -
 Since it is difficult to recognize the fundamental
mode of vibration, the fundamental frequency is
usually calculated from the difference of two
adjacent harmonics which are depicted by two
adjacent rises in the pulse amplitude.

Resonance Method
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 This method is used for the inspection of large ingots
and castings particularly when the attenuation is
high and gross defects are present.
 The method does
does not
not give
give the
the size
size and
and location
location of
of
 The method does
does not
not give
give the
the size
size and
and location
location of
of
the
the defect
defect.
. In addition good mechanical coupling
and alignment of the two probes is essential.

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 Techniques of ultrasonic testing are either of the
contact type or the immersion type.

 In
In the
the contact
contact type
type, the probe is placed in direct
contact with the test specimen with a thin liquid film
used as a couplant for better transmission of
used as a couplant for better transmission of
ultrasonic waves in to the test specimen.

 In
In the
the immersion
immersion type
type, a waterproof probe is used
at some distance from the test specimen and the
ultrasonic beam is transmitted in to the material
through a water path or water column.

Contact Type Techniques
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Normal
Normal Beam
Beam Techniques
Techniques:
:
 In the normal beam technique the ultrasonic beam is
projected perpendicularly in to the test specimen. This
technique may use either single, double or SE normal
beam probes.
beam probes.
 With the single probe, the transducer of the probe acts
as both transmitter and receiver.
 In this technique an ultrasonic beam pulse is projected
at in to the specimen and echoes from the flaws within
the specimen and from the back wall of the specimen
are received.

Straight beam inspection techniques:
Direct contact,
single element probe
Direct contact,
dual element probe
Fixed delay
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Immersion testing
Through transmission

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
 Angle
Angle Beam
Beam Techniques
Techniques
 The angle beam technique is used to transmit ultrasonic
waves in to a test specimen at a predetermined
predetermined angle
angle
to
to the
the test
test surface
surface.
.
 According to the angle selected, the wave modes
produced in the test specimen may be mixed
 According to the angle selected, the wave modes
produced in the test specimen may be mixed
longitudinal and transverse, transverse only, or surface
wave modes.

 Transverse
Transverse waves
waves at various angles of refraction
between 35
35°
° and
and 80
80°
° are used to locate defects whose
orientation is not suitable for detection by normal beam
techniques.

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
 Surface
Surface Wave
Wave Techniques
Techniques
 Surface wave techniques have been used very successfully
for a great number of applications, particularly in the
Aircraft Industry.
 The main advantage of surface waves is that they follow
gentle contours and are reflected sharply only by sudden
gentle contours and are reflected sharply only by sudden
changes in contour, thus making it a very useful tool for the
examination of complex shaped components.
 The main limitation of these waves is that they are almost
immediately attenuated if the surface finish is rough, is
covered in scale or a liquid (such as the couplant), or if any
pressure is applied by another object (such as the hand of
the operator ).

Immersion Testing Techniques
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 Immersion testing techniques are mainly used in the
laboratory
laboratory and
and for
for large
large installations
installations doing
doing automatic
automatic
ultrasonic
ultrasonic testing
testing.
. It has the advantage that uniform
couplant conditions are obtained and longitudinal and
transverse waves can be generated with the same
probe simply by changing the incident beam angle.
probe simply by changing the incident beam angle.
 In the immersion technique both the probe and the test
specimen are immersed in water. The ultrasonic beam is
directed through the water in to the test specimen, using
either a normal beam technique for generating
longitudinal waves or an angle beam technique for
generating transverse waves.

surface =
sound entry
backwall flaw
1 2
water delay
Immersion testing
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0 2 4 6 8 10 0 2 4 6 8 10
IE IE
IP IP
BE BE
F
1 2

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Immersion testing
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 In the bubbler or squirter technique, the ultrasonic beam
is directed through a water column in to the test
specimen.

 This
This technique
technique is
is usually
usually used
used with
with an
an automated
automated system
system
for
for high
high speed
speed scanning
scanning of
of plate,
plate, sheet,
sheet, strip
strip,
, cylindrical
cylindrical
for
for high
high speed
speed scanning
scanning of
of plate,
plate, sheet,
sheet, strip
strip,
, cylindrical
cylindrical
forms
forms and
and other
other regularly
regularly shaped
shaped forms
forms.
.
 The ultrasonic beam is either directed in a
perpendicular direction (i.e. normal direction ) to the
test specimen to produce longitudinal waves or is
adjusted at an angle to the surface of the test specimen
for the production of transverse waves.

Immersion testing
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Immersion testing
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 In the wheel transducer technique the ultrasonic
beam is projected through a water-filled tire in to
the test specimen.
 The probe, mounted on the wheel axle, is held in a
 The probe, mounted on the wheel axle, is held in a
fixed position while the wheel and tire rotate freely.
 The wheel may be mounted on a mobile apparatus
that runs across the specimen, or it may be mounted
on a stationary fixture, where the specimen is
moved past it

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Equipment
Equipment
Equipment for ultrasonic testing is very diversified.
Proper selection is important to insure accurate
inspection data as desired for specific applications.
In general, there are three basic components that
comprise an ultrasonic test system:
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comprise an ultrasonic test system:
- Instrumentation
- Transducers
- Calibration Standards

1. TRANSDUCERS
• Transducers are manufactured in a variety of forms,
shapes and sizes for varying applications.
• Transducers are categorized in a number of ways which
include:
- Contact or immersion
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- Contact or immersion
- Single or dual element
- Normal or angle beam
• In selecting a transducer
for a given application, it
is important to choose the
desired frequency,
bandwidth, size, and in some cases focusing
which optimizes the inspection capabilities.

Contact Transducers
Contact transducers are
designed to withstand
rigorous use, and usually have
a wear plate on the bottom
surface to protect the
piezoelectric element from
contact with the surface of the
piezoelectric element from
contact with the surface of the
test article.
Many incorporate ergonomic
designs for ease of grip while
scanning along the surface.
APME/JECC
73

Contact Transducers (cont.)
 Contact transducers are available with
two piezoelectric crystals in one
housing. These transducers are called
dual element transducers.
 One crystal acts as a transmitter, the
other as a receiver.
 This arrangement improves near surface
resolution because the second
transducer does not need to complete a
transmit function before listening for
echoes.
 Dual elements are commonly employed
in thickness gauging of thin materials.
APME/JECC
74

Contact Transducers (cont.)
 A way to improve near surface
resolution with a single element
transducer is through the use of a delay
line.
 Delay line transducers have a plastic
piece that is a sound path that provides
a time delay between the sound
generation and reception of reflected
generation and reception of reflected
energy.
 Interchangeable pieces make it
possible to configure the transducer
with insulating wear caps or flexible
membranes that conform to rough
surfaces.
 Common applications include thickness
gauging and high temperature
measurements.
APME/JECC
75

Angle beam Transducers
 Angle beam transducers
incorporate wedges to introduce
a refracted shear wave into a
material.
 The incident wedge angle is used
with the material velocity to
determine the desired refracted
determine the desired refracted
shear wave according to Snell’s
Law)
 Transducers can use fixed or
variable wedge angles.
 Common application is in weld
examination.
APME/JECC
76

Immersion Transducers
Immersion transducers are
designed to transmit sound
whereby the transducer and test
specimen are immersed in a liquid
coupling medium (usually water).
 Immersion transducers are
manufactured with planar,
cylindrical or spherical acoustic
lenses (focusing lens).
APME/JECC
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APME/JECC

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APME/JECC

2. INSTRUMENTATION
 Ultrasonic equipment is usually purchased to satisfy
specific inspection needs, some users may purchase
general purpose equipment to fulfill a number of
inspection applications.
 Test equipment can be classified in a number of
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 Test equipment can be classified in a number of
different ways, this may include portable or stationary,
contact or immersion, manual or automated.
 Further classification of instruments commonly divides
them into four general categories: D-meters, Flaw
detectors, Industrial and special application.

D-meters or digital thickness gauge
 D-meters or digital thickness
gauge instruments provide
the user with a digital
(numeric) readout.
 They are designed primarily
for corrosion/erosion
for corrosion/erosion
inspection applications.
• Some instruments provide the user with both a digital
readout and a display of the signal. A distinct advantage
of these units is that they allow the user to evaluate the
signal to ensure that the digital measurements are of the
desired features.
APME/JECC
81

Flaw detectors
 Flaw detectors are instruments
designed primarily for the
inspection of components for
defects.
 However, the signal can be
evaluated to obtain other
information such as material
information such as material
thickness values.
 Both analog and digital display.
 Offer the user options of gating
horizontal sweep and amplitude
threshold.
APME/JECC
82

Industrial flaw detection instruments
 Industrial flaw detection
instruments, provide users with
more options than standard
flaw detectors.
 May be modulated units
allowing users to tailor the
allowing users to tailor the
instrument for their specific
needs.
 Generally not as portable as
standard flaw detectors.
APME/JECC
83

Immersion ultrasonic scanning systems
 Immersion ultrasonic scanning systems
are used for automated data
acquisition and imaging.
 They integrate an immersion tank,
ultrasonic instrumentation, a scanning
bridge, and computer controls.
 The signal strength and/or the time-
 The signal strength and/or the time-
of-flight of the signal is measured for
every point in the scan plan.
 The value of the data is plotted using
colors or shades of gray to produce
detailed images of the surface or
internal features of a component.
APME/JECC
84

Images of a Quarter Produced With an Ultrasonic
Immersion Scanning System
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Gray scale image produced using
the sound reflected from the front
surface of the coin
Gray scale image produced using the
sound reflected from the back surface
of the coin (inspected from “heads” side)

3. CALIBRATION STANDARDS
 Calibration is a operation of configuring the ultrasonic test
equipment to known values. This provides the inspector with
a means of comparing test signals to known measurements.
 Calibration standards come in a wide variety of material
types, and configurations due to the diversity of inspection
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types, and configurations due to the diversity of inspection
applications.
 Calibration standards are typically manufactured from
materials of the same acoustic properties as those of the
test articles.

Calibration Standards (cont.)
Thickness calibration
standards may be flat or
curved for pipe and tubing
applications, consisting of
simple variations in material
thickness.
ASTM Distance/Area Amplitude
87
thickness.
Distance/Area Amplitude
standards utilize flat bottom
holes or side drilled holes to
establish known reflector size
with changes in sound path
form the entry surface.
NAVSHIPS

Calibration Standards (cont.)
There are also calibration
standards for use in angle
beam inspections when
flaws are not parallel to
entry surface.
IIW
DSC DC Rhompas
88
These standards utilized
side drilled holes, notches,
and geometric
configuration to establish
time distance and
amplitude relationships.
SC
ASME Pipe Sec. XI

Qualification Standards
Qualification standards
differ from calibration
standards in that their
use is for purposes of
varying proper
equipment operation
AWS Resolution DC-dB Accuracy
89
equipment operation
and qualification of
equipment use for
specific codes and
standards.
IOW Beam Profile

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DATA PRESENTATION
 Information from ultrasonic testing can be presented in a
number of differing formats.
 Three of the more common formats include:
 A-scan
B-scan
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 B-scan
 C-scan

Data Presentation - A-scan

 A
A-
-scan presentation displays
scan presentation displays
the amount of received
the amount of received
ultrasonic energy as a function
ultrasonic energy as a function
of time.
of time.
 Relative discontinuity size can
be estimated by comparing
Signal
Amplitude
be estimated by comparing
the signal amplitude to that
from a known reflector.
 Reflector depth can be
determined by the position of
the signal on the horizontal
sweep.
Time
Signal
Amplitude
Time
APME/JECC
93

Data Presentation - B-scan

B
B-
-scan presentations display a
scan presentations display a
profile view (cross
profile view (cross-
-sectional)
sectional)
of a test specimen.
of a test specimen.
Only the reflector depth in the
cross-section and the linear
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cross-section and the linear
dimensions can be
determined.
A limitation to this display
technique is that reflectors
may be masked by larger
reflectors near the surface.

Data Presentation - C-scan

 The C
The C-
-scan presentation displays a plan type view of the test
scan presentation displays a plan type view of the test
specimen and discontinuities.
specimen and discontinuities.
 C-scan presentations are produced with an automated data
acquisition system, such as in immersion scanning.
 Use of A-scan in conjunction with C-scan is necessary when
depth determination is desired.
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depth determination is desired.
Photo of a Composite
Component
C-Scan Image of
Internal Features

ADVANTAGE OF ULTRASONIC TESTING
 Sensitive to small discontinuities both surface and subsurface.
 Depth of penetration for flaw detection or measurement is superior
to other methods.
 Only single-sided access is needed when pulse-echo technique is
used.
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used.
 High accuracy in determining reflector position and estimating size
and shape.
 Minimal part preparation required.
 Electronic equipment provides instantaneous results.
 Detailed images can be produced with automated systems.
 Has other uses such as thickness measurements, in addition to flaw
detection.

LIMITATIONS OF ULTRASONIC TESTING
 Surface must be accessible to transmit ultrasound.
 Skill and training is more extensive than with some other methods.
 Normally requires a coupling medium to promote transfer of sound
energy into test specimen.
 Materials that are rough, irregular in shape, very small,
exceptionally thin or not homogeneous are difficult to inspect.
97
 Materials that are rough, irregular in shape, very small,
exceptionally thin or not homogeneous are difficult to inspect.
 Cast iron and other coarse grained materials are difficult to inspect
due to low sound transmission and high signal noise.
 Linear defects oriented parallel to the sound beam may go
undetected.
 Reference standards are required for both equipment calibration,
and characterization of flaws.

Block diagram: Ultrasonic Instrument
amplifier
horizontal
IP
screen
98
work piece
probe
sweep
clock
pulser
BE

Sound reflection at a flaw
Probe
s
99
Probe
Flaw
Sound travel path
Work piece

Plate testing
IP
F
BE
100
delamination
plate
0 2 4 6 8 10
F
IP = Initial pulse
F = Flaw
BE = Backwall echo

s
Wall thickness measurement
101
0 2 4 6 8 10
s
s
Corrosion

Weld inspection
0 20 40 60 80 100
a = s sinß
a' = a - x
d' = s cosß
s
F ß = probe angle
s = sound path
a = surface distance
a‘ = reduced surface distance
d‘ = virtual depth
102
0 20 40 60 80 100
s
a
a'
d
x
d = 2T - t'
Lack of fusion
Work piece with welding
d‘ = virtual depth
d = actual depth
T = material thickness
ß

MODULE
MODULE-
-4
4
103
 Ultrasonic Testing (UT): principle, types of waves, frequency,
velocity, wavelength, reflection, divergence, attenuation, mode
conversion in ultrasonic UT testing methods contact testing and
immersion testing, normal beam and straight beam testing,
angle beam testing, dual crystal probe, ultrasonic testing
angle beam testing, dual crystal probe, ultrasonic testing
techniques resonance testing, through transmission technique,
pulse echo testing technique, instruments used UT, accessories
such as transducers, types, frequencies, and sizes commonly
used Reference blocks with artificially created defects,
calibration of equipment, Applications, advantages, limitations,
A, B and C scan - Time of Flight Diffraction (TOFD).

Assignment 2.1
104
 Write short notes on dual crystal probe and
Time of Flight Diffraction (TOFD).
Describe Piezo electric effect and piezo electric
 Describe Piezo electric effect and piezo electric
transducers electro magnetic acoustic transducer

UT _ Ultrasonic Testing

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