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Lecture - 3
Non Destructive EvaluationNon Destructive Evaluation
Outline of the LectureOutline of the LectureIntroduction to Non destructive testing and evaluation techniques
NDE Parameters for Correlation of Microstructure, Properties, Residual Stresses, and Deformation -
Magnetic Barkhausen Emission TechniquesUltrasonic Testing MethodsX-Ray Diffraction MethodAcoustic Emission TestingInfrared Thermography
Summary
Science and Technology of NDT -Inspiration from Nature
InfraredOptical
Crane
Ultrasound
Eagle
Acoustic
Bat
Spectroscopy
Ant
Beetle
Non Destructive Testing (NDT) – an inseparable part of Quality Chain. Provides vital measurements and feedback.
Non Destructive Testing (NDT)?
Testing or inspection of materials / objects / components / structures without destroying or impairing their intended use is Non Destructive Testing (NDT)
Two types of material testingDestructive (tensile, creep, fatigue etc.)
Non Destructive (visual, ultrasonic, eddy current, X-radiography, magnetic particle etc.)
Component can be used, as-it-is, after NDT
Forging
Rolling
Extrusion
Casting
Welding
Segregations
InclusionsOxide, Silicates,
Alumina, Tungsten
Hydrogen
Precipitates
ServiceRelated
MetallurgyRelated
Origin of Defects
ProcessRelated
Temperature
Pressure
Environment
Non destructive Testing (NDT) to Non Destructive Evaluation (NDE)
• NDT– Detection of defects
• NDE– Detection & evaluation of defects– Characterization of microstructures– Evaluation of mechanical properties– Evaluation of residual stresses
NDE - Multi-disciplinary naturePhysicsMetallurgyEngineering/TechnologySensor TechnologyRobotics (automation)
Various NDE Techniques for Various NDE Techniques for CharacterisingCharacterising Different FeaturesDifferent Features
R&D in NDE Techniques enable us to do comprehensive analysis of microstructures and stresses in materials and components
Ref: P. Hoeller, in “Non-destructive characterisation of Materials II” (eds. J.F. Bussiere et.al.) (1997) 101-106
Steps in NDEEssential steps involved in NDE are:
1. Application of a testing or interrogation medium
2. Modification of the testing medium by defects/microstructure/stresses in materials
3. Detection of this change/ manifestation by a suitable detector or SENSOR
4. Conversion of detector output into a suitable data/ signal/ image/ information
5. Interpretation of the information obtained after suitable calibration and processing
Fabrication quality
In-service degradation
• Magnetic Barkhausen Emission√• Ultrasonics√• X-ray Diffraction√• Acoustic Emission√• Infrared Thermal Imaging√• Positron Annihilation• Laser Scattering• Eddy Currents• …….
NDE of Microstructures and Residual Stresses
Magnetic Barkhausen EmissionWhen a ferromagnetic material is subjected to varying magnetic field, the discrete changes in the flux density during magnetization induce small voltage pulses in pick-up coils. This phenomenon is called Magnetic BarkhausenEmission (MBE) and is attributed to the jumps of domain walls overcoming microstructural obstacles and hence are very sensitive to microstructural variations.
Rotation
Reversible Boundary Displacement
Irreversible Boundary Displacement
Field (H)
Flux
(B)
Magnetic Barkhausen Emission
∫ V dt = n . ∆ Φ / τcoil
V = Voltage induced in the coiln = No. of coil turns∆Φ = Change in flux densityΤcoil = Time constant of coil
MBE is used to determine grain size, volume fraction of precipitates, strength, damage fatigue, residual stresses, hardening case depth etc.No Field Low Field High Field
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
0.0
0.1
0.2
0.3
0.4
0.5
MB
E R
MS
Volta
ge
Applied magnetic Field
Time domain signal
Magnetization process
MBE RMS PLOT
Influence of two types of obstacles for domain wall movement
RM
S V
OLT
AG
E O
F TH
E M
BN
, v
-0.350,0
-0.7
0,4
0.35APPLIED CURRENT, A
0
Hgb
0.7
cpH
0,8
1.2
1.6
Hgbm
Hcp
m
Optimisation of MBE test parameters to obtain high intensity and distinct two peaks in quenched and tempered carbon steel
-2 -1 0 1 2 3
0.0
0.5
1.0
1.5
2.0
2.5
0.01 sec
0.1 sec
30 sec
10 sec
MB
E R
MS
Volta
ge
Applied Magnetic Field
Effect of Sweep rate on MBE
B-H Loop and MBETempering treatment
Sensitive to fine changes in microstructuralfeatures
RMS voltage Peak height (Number & nature of obstacles)
RMS voltage Peak position (Ease of Magnetization)
Detects only magnetic properties, fine microstructural changes
are not distinguished
B-H Loop Parameters
Coercivity
Retentivity
Saturation Magnetization
MBE RMS Plot
Peak voltage position
Peak voltageheight
MBE for Materials Characterization
• Determination of quenched and tempered microstructures in ferromagnetic materials (ex. carbon steel)
• Determination of tensile strength in Cr-Mo steels• Assessment of Post Weld Heat Treatment in Cr-Mo
steel weld joint• Assessment of LCF damage in Cr-Mo steel
MBE for Determination of Microstructures in 0.2% Carbon Steel
0.5 h
100 h0.2% CARBON STEELTEMPERED AT 873 K
CORRELATION COEFFICINT = 0.96
0.20
0.15
0.10
0.05
0.00-0.10 -0.05 0.00 0.05 0.10
MBE PEAK 1 POSITION, A
*
**
*
REC
IPR
OC
AL
OF
GR
AIN
SIZ
E, 1/µ
m
0.60 0.2% CARBON STEELTEMPERED AT 873 KCORRELATION COEFFICIENT = 0.990.50
0.40
0.30
0.20
0.10
0.000.25
**
*
*
*
0.30 0.35 0.40
MBE PEAK 2 POSITION, A
AV
ERA
GE
CA
RB
IDE
SIZE
, µm
Correlation between MBE Parameters with size of grains and carbides in 0.2% carbon steel
Optical micrographs
MBE for Determination of Tensile Strength
1 0 µ m ⎥ ⎯ ⎢ ( a ) ( b )
( c ) ( d )
1 0 µ m ⎥ ⎯ ⎢
1 0 µ m ⎥ ⎯ ⎢
1 0 µ m ⎥ ⎯ ⎢
2 h 10 h
20 h 100 h
10µ 10µ
10µ 10µ
Tempering softens quenched structure: Reduction in dislocation density and precipitation of carbides/ carbonitrides -Reduces tensile strength and increases MBE
MBE assessment of PWHT in TTS weld jointsof a steam generator
Magnetic Barkhausen
emission response to post weld
stress relief treatment
MAGNETIC BARKHAUSEN EMISSION FOR ASSESSMENT OF LOW CYCLE FATIGUE DAMAGE Cyclic Hardening
Dislocation tangles –Decrease in MBE
Cyclic SofteningDislocation cell structure – Enhanced domain wall movement within the cells-Increase in MBE
Cyclic SaturationStabilization of cells-No change in MBE
Crack InitiationAdditional reverse domains form at crack surface- Increase in MBE
Ultrasonic Materials Characterization
-610
-810
-1010
1A 100A 1µm
MIC
RO
STRU
CTU
RE
/ D
EFEC
T
[m]10-4
10-2
m100µ 10mm
Dimension of structural featuresDimension of structural features
100 101 102 103 104 105 106 107 108 109 1010 1011
100 101 102 103 104 105 106 107 108 109 1010 1011
Ultrasonic flaw detection
Acoustic Microscopy
Ultrasonic materials characterization
Acoustic Emission
Audible Sound
Frequency, Hz
Medical Ultrasound
Acoustic wave spectrumAcoustic wave spectrum
Ultrasonics for Material Characterization• The speed of wave propagation and its energy loss due to
interaction with material microstructure are the key factors for the ultrasonic determination of microstructuralfeatures and properties of materials.
0 200 400 600 800
A2
A1
t
Am
plitu
de, A
.U.
Time, ns
0 10 20 30 40 50 60 70
0
20
40
60
80
100
12030µ
78µ
138µ
Ampl
itude
, A.U
.Frequency, MHz
Spectral analysis• Independent of couplant condition• Highly attenuating material
2xthicknessVelocity = ----------------
transit time20log(A1/A2)
Attenuation (dB/mm) =----------------2xthickness
a) Particle vibrationA
mpl
itude
Longitudinal waveLongitudinal waveWave Propagation Direction
λ
)2-(1 )(1)-E(1ννρ
ν+
=LV
Transverse waveTransverse wave
LT VGV 5.0≈=ρ
Poisson’s ratio (ν): Lateral contraction per unit breadth / Longitudinal extension per unit length (Gives the character of the atomic bonding forces)
Ultrasonic parameters
ρGVT =
)2-(1 )(1)-E(1ννρ
ν+
=LV
Evaluation of StressesV = V0 + Aσ
I = I0 exp (-αx)
αa = a1f 0.5 + a2f + a3f2
αs ∝ d3 f 4 (Rayleigh scattering - λ > d)
sa ααα +=
initial pulse
0 2 4 6 8 10
back surfaceecho
crackecho
Oscilloscope, or flaw detector screen
plate
crack
α - Attenuation coefficientαa- Absorption coefficient αS- Scattering coefficientd - scatterer size
VL-Ultrasonic longitudinal wave velocity VT - Ultrasonic shear wave velocityG- Shear modulus, E- Young’s modulus,ν- Poisson’s ratio, ρ- Density
I- Energy intensity, Io - Intensity of the incident ultrasonic beam,f- frequency, a1 a2 and a3 constantsα - Total attenuation coefficientαa- Absorption coefficient αS- Scattering coefficient
V - Ultrasonic velocity in presence of stressV0 - Stress-free velocityA - Acoustoelastic constantσ - Stress
Ultrasonic attenuation – Grain size in stainless steel
αs=Sd3f4
-30
-20
-10
0
10
20
30
138 µm78 µm
30 µm
200 nsAm
plitu
de, A
. U
.
Time, ns
αS- scattering coefficientf - frequencyd - scatterer (ex. Grain) sizeS- constant
αs ∝ d3 f 4 (Rayleigh scattering - λ > d)
Effect of grain size on ultrasonic first back wall echo
Ultrasonics for Materials Characterization
• Spectral approach for grain size determination in austenitic stainless steel
• Attenuation based imaging for assessment of dynamic recrystallization in hot forged D9 alloy
• Velocity for determination of volume fraction γ’ in Nimonic alloy PE -16
• Poisson’s ratio (from velocities) based assessment of ageing induced thermal degradation in Inconel 625
• Velocity for assessment of creep damage in Copper
Ultrasonic spectral approach for grain size determinationUltrasonic spectral approach for grain size determination
YS = Yield strengthfp = Peak frequencyFWHM = Full width at half maximum of ultrasonic signal frequency spectrum
0 10 20 30 40 50 60
0
2
4
6
8
10
12
30 µm
78 µm
138 µm
Am
plitu
de, A
.U.
Frequency, MHz αs=Sd3f4
AISI 316 SS
Similar variation in peak frequency, FWHM and YS with grain size
0 1 2 3 4 5 6 75
10
15
20
25
AISI type 316 SS
d, µm284063
FWHM, MHzPF, MHz
d-1/2, mm-1/2PF
& F
WH
M, M
Hz
150
200
250
300
1112501000
Yiel
d st
reng
th, M
PaYield stress, MPa
Forged to 50%; 1273 K
Little skew in the deformation
Fine grains in one shear band
Fine grains in deformation zone
190 VHN
Coarse grains in dead metal zone
198 VHN
192 VHN
αs=Sd3f4 (Rayleigh scattering - λ > d)
Relative values
γ’ in γ matrix
16.5% Cr, 33.8% Fe, 3.3% Mo, 0.27% Co, 1.2% Ti, 1.24% Al, 0.03% Zr, 0.0155 B and 0.07% CHigh temperature strength and resistance to irradiation induced swelling (FBR core components – cladding tubes and wrapper)Solutionising treatment: 1313K/ 4h
Thermal ageing Volume fraction of γ'973K/16h 0.1101073K/8h 0.0991173K/1h 0.067
Ultrasonic velocity measurements at Frequency: 13 MHz
1313K/ 4h + 973K/16h
A 1313K / 4h
B 1313K / 4h + 1073K / 1h
C 1313K / 4h + 1023K / 8h
D 1313K / 4h + 973K / 16h
5680
0.00 0.04 0.08 0.12
5690
5700
5710
5720
5730
5740
LON
GIT
UD
INAL
VEL
OCI
TY, m
/s
CORRELATION COEFFICIENT = 0.9993
D
C
B
A
VOLUME FRACTION OF γ'
)2-(1 )(1)-E(1ννρ
ν+
=LV
LONGITUDINAL
EQUATION
VELOCITY= 555.5 (VOL. FRACTION OF γ' ) + 5679.4
Ultrasonic velocity for determination of volume fraction of γ’ in Nimonic alloy PE -16
120 140 160 180 200 220 240 260 280 300 320 340 360 3800.2925
0.2950
0.2975
0.3000
0.3025
0.3050
0.3075
0.3100
0.3125
0.3150
0.3175
0.3200
0.3225For the Inconel 625 wrought cracker tubes at HWP, Thal and HWP, Tuticorin in various thermal exposure conditions
Poi
sson
's ra
tio
Hardness, VHN
Virgin (Thal) RSA (Thal) V+747 h (Tuti) RSA+23000 h (Thal) V+57194 h (Tuti) Failed in 1982 (Tuti) MC (~20000h) (Tuti) 120000 h (1-35, Thal) 120000 h (36-70, Thal)
Changes in Poisson’s ratio and hardness for cracker tubes in different service exposed conditions at heavy water plants (V-Virgin, MC-Mini Cracker, RSA-Re-solution annealed)
Ultrasonic measurements can be used to monitor the degradation in mechanical properties
Life span of these tubes for resolution annealing should not be based on merely the service duration, but on some practically measurable parameter, such as Poisson’s ratio and hardness
Assessment of rejuvenation heat treatment of the tubes using ultrasonic measurements
⎟⎟⎠
⎞⎜⎜⎝
⎛−
−=
12
2
2
2
2
2
L
S
L
S
TOFTOF
TOFTOF
ν
Accuracy ~ ± 0.0006
)2-(1 )(1)-E(1ννρ
ν+
=LV
ρGVT =
Poisson’s ratio (ratio of ultrasonic velocities) to assess extent of thermal degradation during service exposure of Inconel 625
Study of defects/precipitates in beta-quenched Zircaloy-2
Hardness
MacroscopicMicroscopic
Positron Lifetime Positron S-parameter
Evolution of defects and hard intermetallic
precipitates in β-matrix
Microstructure
Ultrasonic Velocity
Padma Gopalan et al., JNM 345, 162 (2005)
Ultrasonic velocity for assessment of creep damage
• Ultrasonic parameters:longitudinal and shear wave velocities
• Microstructuraldegradation: void formation, grain boundary cavitation, micro cracks and macrocracks
• Application: Assessment of creep damage in in components in service.
Ultrasonic Velocity for Assessment of Creep Damage
Material: Copper (purity 99.90%)Creep test temperatures: 5000C, 6000C and 7000C
Remaining creep life can be predicted using ultrasonic velocity measurements
t / t
MERELY
Optimum aging 755K (3 -10h)Shear wave velocity above 2950 m/s - ensures presence of precipitatesMBE peak RMS voltage above 1.7 V - ensures absence of austenite
0.0
0.5
1.0
1.5
2.0
2.5
2850 2875 2900 2925 2950 2975 3000
0.1
0.251
3 10
3040
70
100
Shear wave velocity, m/s
MB
E, R
MS
Volta
geSA Acceptable-
optimum aging
Unacceptable-Reverted austenite
Unacceptable-inadequate precipitates
Combination of NDE (Ultrasonic and Magnetic Barkhausen) parameters for qualification of thermal
ageing treatment in M250 Maraging Steel
NDE for evaluation of residual stresses
• Residual stresses“Residual stresses are those stresses which are 'locked' into components and structures without the application of any other external load”
• NDE techniques– Ultrasonics– X-ray diffraction
Tensile
Compressive
Ultrasonic Velocity for Residual stresses measurements in Materials
• Ultrasonic parameter: Change in velocity in presence of stress and use of acoustoelastic constant (AEC)
• Residual stress measurements:• Step1- Determination of AEC (A)• Step2- Velocity measurement in material• Step3- Residual stress estimation using V=V0+Aσ
• Application: Residual stress measurements in thick austenitic stainless steel welds
Ultrasonic Velocity for Qualification of Stress Relieving Heat Treatment in Steel Welds
V = Vo + (AEC)σ
AEC = Acousto-elastic Constant
INCI
DENT
BEAM
DIFFRACTED
BEAM
BRAGG'S LAW 2d Sin =
d
INTE
NSI
TY d
dd
= STRAIN
X-Ray Diffraction Technique for Residual Stress Measurements
Spatial Resolution : 1-2 mmDepth of analysis : 10-30 micron
Compressive stresses – to resist fatigue crack initiation
During operation - Compressive stress gets slowly changes to tensile stress, under fatigue loading conditions (e.g Landing gear of aircraft)
XRD system for assessment of fatigue damage by evaluation of residual stresses in components and also to check for adequacy of rejuvenation treatment employed for introducing compressive stresses.
NUMBER OF LANDINGS
-6000
RES
IDU
AL
STR
ES
S, M
Pa
-200
-400
-500
-300
-100
100
0
800400
1200
XRD based Residual Stress Measurements for Life Assessment of Undercarriages of Fighter Aircrafts
Residual stress variation as a function of number of landings (550 MPaCompressive stress in new landing gears)
K
7-FRONT8-REAR
5-FRONT6-REAR
3-FRONT4-REAR
9
10
VIEW -K
2
1
REGIONS OF RESIDUAL
M AIN LANDING GEAR STRUT
STRESS MEASUREM ENTS
Stress critical regions and corresponding residual stress values after 3600 landings (900 MPa Compressive stress in new landing gears)
RE
SID
UA
L S
TRE
SS
, MP
a
-600 0
-400
-500
-300
-100
-200
0
300DEPTH IN MICRONS
100 200
Residual stress as a function of depth in the landing gear after 1200 landings
12345678910
519
592501
657621
480
438
621592
402
798
846831
854826779
763
847850756
843844853897837821861874812860
LOCATIONTOP
RESIDUAL STRESS (MPa)COMPRESSIVE
DEPTH BELOWTOP SURFACE10µ 200µ
NDE for Deformation
• Acoustic Emission
• Infrared thermography
FLUID LEAKAGE
PRESSUREVESSEL
CRACKINITIATION &PROPAGATION
TRANSFORMATIONPHASE
MARTENSITE
AUSTENITE
PLASTICDEFORMATION
ACOUSTIC EMISSION
TRANSIENT RELAXATION OF STRESS & STRAIN FIELDS
RAPID RELEASE OF ENERGY NEW SURFACE FORMATION
MECHANICAL WAVE (OR)STRESS WAVE (OR)ACOUSTIC EMISSION
HEAT
ETC.
Principle of AET
Types of acoustic emissions that occur during plastic deformation of different materials
Carbon steel
Al, Cu, Brass
Brass, Al alloys and stainless steel at high temperatures (YP and PLC)
Precipitation hardened Al alloys (Yielding & microcracking)
Stainless steels& cold worked materials
AE during tensile testing of Nimonic PE-16
Solution Annealed (1313 K/4h) Only γ
SA +1023 K/24hγ + coarse γ′
SA +1173 K/2hγ + MC
Particle shearingFine γ′
Orowan loopingCoarse γ′
Decohesion and fracture of CarbidesInfluence of deformation processes
FR and GB source operationDecohesion and fracture of MC carbidesParticle shearingOrowan looping
Thermography
Thermal imaging or Infrared (IR) Thermography or Thermography is the mapping of temperature profiles on the surface of an object or a component.
Any object above absolute zero, emits electromagnetic radiations. At Ambient temperatures and above, these radiations are predominately infrared radiations.
Intrinsic photonic detectors: Detector fused in Si readout circuits - HgCdTe /8-12µm,3-5µm
Infrared Thermal Imaging
Advantages of Thermography
• Non–contact nature
• Real time ability
• Ability to provide full field images that helps in visualising the process
• Wide range of applications
• Direct applicability to engineering components
Limitations of Thermography• Lower sensitivity to subsurface information of the object
• Difficult to employ on thermally reflective surfaces
• Interpretation requires knowledge, training and experience
Infrared Thermal Imaging for Monitoring Tensile Deformation in a Carbon steel
Element C Mn P S Fe(Wt. %) 0.23 0.40 0.04 0.04 Balance
• Tensile deformation at different strain rates
• Temperature variation with strain is recorded
• Region I - Start point to yield point -rise in temperature
• Region II- Yield point to UTS- gradual rise with strain
• Region III- Steep rise in temperature with strain with maximum at fracture
• Application: Early identification of zones of failure during deformation
IRT imaging for Tensile Deformation
25.0°C
38.0°C
26
28
30
32
34
36
38
24.4% 47.2% 59.7% 66.2%
25.0°C
50.0°C
25
30
35
40
45
50
6.7 x 10– 4 /sec
7.1% 26.5% 47.3% 54.2% 58.9% 60%
The zone of failure during tensile deformation could be predicted well in advance.
-50 -40 -30 -20 -10 0 10 20 30 40 50300
310
320
330
340
350
360
370
55.9%
47.72%
47.31%34.4%17.2%5.38%
TEM
PER
ATU
RE(
Kel
vin)
DISTANCE(mm)
Strain rate: 1.7 X 10-2/sec
1.7 X 10-3 /secAs strain rate increases thermal emission increasesTemperature profile along gauge length
at different strain levels
Unique Applications of Unique Applications of NDENDE
Investigation of microstructural changes in M250 grade Maraging steel using positron annihilation
Evaluation of changes in defect structure associated with annihilation of defects and intermetallic precipitation
0.5 µm
A
B
C
Isochronal IsothermalRegime I Regime II Regime III
0.25 1 10 100130
132
134
136
138
140
142
144
146
300
350
400
450
500
550
600
650
-5
0
5
10
15
20
25
30
35
Aging time, h
Posi
tron
life
time,
τ (p
s)
Har
dnes
s, V
HN
Vol.%
of a
uste
nite
Positron lifetime Hardness Vol.% of austenite
Aging time, h
Posi
tron
life
time,
τ (p
s)
Har
dnes
s, V
HN
Vol.%
of a
uste
nite
Positron lifetime Hardness Vol.% of austenite
600 700 800 900 1000130
135
140
145
150
155
600 700 800 900 1000
350
400
450
500
550
600
600 700 800 900 1000
0
5
10
15
20
25
Positron lifetime
SA
SA
SA
Hardness
Har
dnes
s, V
HN
Vol.% of austenitePosi
tron
life
time,
τ(ps
)
Aging temperture, K
Vol.
% o
f aus
teni
te
TEM image- 755K/100h A- Austenite, B-Ni3(Ti, Mo), C-Fe2Mo
K.V. Rajkumar et al., Philosophical Magazine A (accepted )
Remote field eddy current detection of wall loss in ferro-magnetic SG tubes (5%, 150 microns)
Eddy current based detection of grain boundary degradation (µm-nm)
EC-GMR imaging of far-side corrosion in steels (12 mm below the accessible surface)
Barkhausen emission for early detection of fatigue damage (3 cycles)
Eigen based enhancement of GMR-flux leakage images (SNR 20 dB)
Electromagnetic NDE Techniques -
Range and Versatility
SQUIDs sensor for mapping of magnetic fields from heart and brain (pico Tesla)
Transient electro-magnetic method for exploration of Uranium mines & profiling (500m beneath earth)
Ab initio design of sensors, equipment, modeling and validation from nm range to km length i.e. 10-9 to 103 scale of 1012
(A wide range of applications)
100 101 102 103 104 105 106 107 108 109 1010 1011
100 101 102 103 104 105 106 107 108 109 1010 1011
Ultrasonic flaw detection
Acoustic Microscopy
Ultrasonic materials characterization
Acoustic Emission
Audible Sound
Frequency, Hz
Medical Ultrasound
Ca Oxalate kidney stone acoustic microscopy(10 nm thick layers)
Acoustic amplification based tests for dislocation studies (µm-nm)
Acoustic NDE domain for detection of precipitates, phases, dislocations, grain size, inclusions, DSA in steels (µm-nm) Non-linear ultrasonics
for dislocations and micro-cracks (µm)
Kaiga Ring beam using impact echo testing
AcousticNDE Techniques -
Range and VersatilityAcoustic Simulation of PE-16 (µm size precipitates)
Ultrasonic study of Humpy musical pillars
Ab initio design of sensors, equipment, modeling and validation from nm range to tens of m length i.e. 10-9 to 103 scale of 1012 (A wide range of applications)
Thermal Imaging for Detection of Breast CancerProcessed image + mathematical transform + graded thermal analysis for detection of cancerous lesion
Averaged Image After Hough Transform
AFM Analysis of Kidney StonesCALCIUM OXALATE MONO-HYDRATE KIDNEY STONE (Layered Structure)
1mm 1mmZ=0 µm (At Surface)
Z=15 µm (Defocus)
SQUID Sensors for Magnetoencephalography
SQUID fabricated at Kalpakkam
Sensor specifications
Junction area 5µm x 5µm
Sensitivity10 fT/√Hz
Detection of Fatigue in SS 304 L(N) welds
f1 Flexural frequency (FF)f2 First overtone of FF
Mahamandapam showing pillars and musical columns Sound pattern recorded for 4 musical
columns in pillar 16 (Veena).
0.00 0.25 0.50 0.75 1.00 1.250
200
400
600
800
1000
1200
1400
1600
1800
2000
2200 f1 2.64334f1
(f1=Calculated flexural resonance frequency )
Highest peak 2nd highest peak 3rd highest peak
Pea
k fre
quen
cy, H
z
Velocity x diameter / length2
f1
62114
3
106408.1 −×= wfTDLE
82224
3
10567.21 −×= wfTDLE
f1=703DVL/L2
f2/f1=2.64334
HampiMusical Pillars
Fingerprinting / Characterisation of Ancient South Indian Bronzes
Tallest Dancing Siva (16 ft ht, 9 ft dia) gifted by Department of Atomic Energy standing majestically at European Organization for Nuclear Research (CERN), Geneva
NDE Qualified
RadiographyChallenges
Complexcontours Varyingthickness
Precision photography
In-situ metallography
XRF
NDT of Delhi Iron Pillar NDT of Delhi Iron Pillar - To investigate its mode of fabrication
Side view Top view
AxialCircumferential
Radial
Defect
Schematic of the defect (interface) morphology in Delhi Iron Pillar
Horizontal
Vertical
Larger dimensions in axial and circumferential directions as compared to the radial direction
First experimental indication that Iron pillar
is forged radially.
For the first time, impact echo testing is applied for metallic structures
The Delhi Iron Pillar
Radiograph showing presence of elongated voids detected in the top region at 0.45M below the capital.
200 µm
305 mmHigh density material Interfaces
Metallography structureof Main body (4.88 m)Smaller grains withpointed slag within
Proposed mode of fabrication of the Pillar
Influenced by the natural rock structures
SUMMARYNon destructive evaluation techniques for evaluation of microstructures, mechanical properties, residual stresses and deformation in materials
MBE for determination of microstructures in steels during tempering and PWHT; and, for mechanical properties and LCF damage
Ultrasonics for determination of grain size, dynamic recrystallisation, volume fraction of precipitates, and damage assessment (thermal degradation, creep and fracture toughness).
Ultrasonic and XRD for non destructive evaluation of residual stresses.
AET and IRT to characterize deformation behaviour and early identification of failure region.
Recommended