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.