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Standardization on Mechanical Testing for Safety and Reliability of Structures

– Instrumented Indentation

Department of Materials Science and Engineering, Seoul National University, Seoul, Korea

Young-Cheon Kim, Seung-Kyun Kang, Hee-Jun Ahn, Dongil Kwon

May 24, 2011

1

Contents

::: I. Introduction▪ NMMRL & FRONTICS▪ Instrumented Indentation Test (IIT)

::: II. Evaluation of Mechanical Properties Using IIT

::: III. Standardizations & Activities▪ International Standardizations▪ Activities

▪ Tensile Properties▪ Residual Stress▪ Fracture Toughness

2

Nano-Mechanics & Micro-Reliability Lab.

1994 2000 20031999 2009

Origin[1994]

NRL[1999]

FRONTICS[2000]

ASME[2009~]

ISO[2003~2008]

Material & Applied Mechanics Lab. Nano-Mechanics & System Characterization Lab.

Nano-Mechanics & Micro-Reliability Lab.Nano-Assessment & Micro-Reliability Lab.

Dongil KwonProfessor

Education

1987, Ph.D., Materials Science & Eng., Brown University1981, M.S., Metallurgical Eng., Seoul Nat’l University1979, B.S., Metallurgical Eng., Seoul Nat’l University

Positions Held2008-2009, Ministerial Advisor in the Korean Ministry of

Education, Science and Technology2003, Visiting Professor, Massachusetts Institute of Technology1994~present, Professor, Seoul National University1990-1994, Associate Professor, Changwon National University1989-1990, Senior Researcher, KRISS1988-1989, Invited Researcher, Max Planck Institute

Research Areas

Ø Non-destructive evaluation of mechanical properties (In-situ & in-field evaluation)

Ø Evaluation of mechanical properties at various environmental conditions

Ø Investigating for mechanical behavior inmicro/nano scale

Ø Assessment of reliability of devices & products

3

FRONTICS

FRONTICS Inc.

High/low temperature chamber system(2007)

AIS compact (2009)

AIS 1000 AIS 2000

AIS 2100 (2003)

AIS 3000 m - AIS n - AIS

2000 2003 2008 2009

Fast & Precise Solutions for Quality & ReliabilityDigital Valley, Gasan-dong, Geumcheon-gu, Seoul, KoreaTEL : 82-2-884-8025 http://www.FRONTICS.com

Foundation1st AIS sellingNT certification

1st oversea sellingISO/ASTM memberKS, KEPIC code

ISO/TR 29381New Tech. awardLaunching n-AIS

ASME TFTMove to digital valley50 machines selling

4

MultiscaleCombined Environment

Simple Procedure

Smart Analysis

Selective Diagnosis

• Temperature• Pressure• Corrosion

• Macro• Micro• Nano

Center for Multi-scale Testing and Assessment at Combined Environment

5

Example of Fracture

Macro Micro/Nano Bio

6

s

s Local behavior

Deformation &Fracture

Growth of max. dominant crack

Fracture Phenomenon

7

System

Material

Module Component

Fracture in macro system

Fracture in micro system

Identification of Root Cause

8

Reliability & Safety Assessment

Deformation & Fracture Behavior of Material

Mechanical Properties of Material

• Flaw information• External load/stress

Analysis of hardening & fracture behavior for• Metal• Ceramic• Polymer• Composite• New-material

• Elastic modulus• Hardness• Strength• Hardening exponent• Fracture toughness

Flow for Reliability Assessment

9

Conventional Test MethodsUniaxial tensile test CTOD test

Impact test X-ray diffraction

10

Limitation of Conventional Tests_Destructive

Destructive !!!

Not applicable in-field

11

Limitation of Conventional Tests_Large Scale TestingSpecimens for tensile test Specimens for fracture test

Not applicable for small scale testing

Large scale testing!!!

12

Instrumented Indentation Test

A novel method to characterize mechanical properties

HardnessElastic modulusTensile propertiesResidual stressFracture toughness

Indentation load-depth curve

Load

Depth

Loading

Unloading

13

Instrumented indentationContinuous indentationDepth-sensing indentationInnovative indentation

“ fingerprint of material like DNA ”

Indentation load-depth curve

Advanced Indentation

Inde

ntat

ion

load

Indentation depth

Tensile stre

ssed

S

Residualstress

Dislocation(pop-in)

Film cracking

Creep

Hardness

Instrumented Indentation Test

14

Smart⇒ Various Properties & Adaptability

Depth

Load

“fingerprint of material”

• Elastic Modulus

• Hardness

• Strength

• Fracture Toughness

• Residual Stress

Scaling⇒ Multi-scale & Real Time

Selectable test

Macro NanoMicro

Simple⇒ Easy & Fast Procedure

Combined environment

In-situ

Complex sample

Merits of Instrumented Indentation Test – 3S

15

Mechanical Properties Obtained by IIT

0 100 200 300 400 5000

100

200

300

400

500

K JC fr

om in

dent

atio

n (M

Pam

0.5)

KJC from CTOD (MPam0.5)

SKS3

SUJ2

SA508

S45C

SCM21

SUS303

X65

X70

Cu

Cu-1

Cu-2 Al20

Al50

ASTM A53

ASME SA335 P12SS400

ASME SA106

SM490

Simple & fast

Tensile property Fracture toughness

Residual stress

Instrumented Indentation

Uniaxial tensile test CTOD test

Hole drillingSaw cuttingX-ray diffraction

0.00 0.05 0.10 0.150

200

400

600

800

Tensile Indentation

16

Strength

17

♦ Step 1Determining contact areataking into considerationplastic pile-up/sink-in

SphericalIndentation

Stress and StrainState in Material÷

øö

çèæ=

Rh,nf

hh max

IT*c

pile

♦ Step 2Defining stress and strain statein materials underneath spherical indenteras representative stress and strain

c

maxT A

F1Y

s = qxe tan=T

♦ Step 3 & 4Fitting to constitutive equation andevaluating tensile properties

True strain, eT

True

stre

ss, s

T

s=E(e-0.002) s=Ken

Representative stress-strain points

E

Instrumented indentation testwith a spherical indenter

Tensile propertiesTensile properties

sy, IT , su, IT , nIT, EIT

Force-depth curveof multiple unloadings

,

♦ Step 1Determining contact areataking into considerationplastic pile-up/sink-in

SphericalIndentation

Stress and StrainState in Material÷

øö

çèæ=

Rh,nf

hh max

IT*c

pile

♦ Step 2Defining stress and strain statein materials underneath spherical indenteras representative stress and strain

c

maxT A

F1Y

s = qxe tan=T

♦ Step 3 & 4Fitting to constitutive equation andevaluating tensile properties

True strain, eT

True

stre

ss, s

T

s=E(e-0.002) s=Ken

Representative stress-strain points

E

Instrumented indentation testwith a spherical indenter

Tensile propertiesTensile properties

sy, IT , su, IT , nIT, EIT

Force-depth curveof multiple unloadings

,

[ISO/TR 29381, 2008]

α

Algorithm for Strength Evaluation

18

Results

0 100 200 300 400 500 600 700 8000

100

200

300

400

500

600

700

800

s y, IT

from

inde

ntat

ion

test

s (N

/mm

2 )

sy from tensile tests (N/mm2)

Yield strength

0 200 400 600 800 1000 12000

200

400

600

800

1000

1200

su from tensile tests (N/mm2)

s u,IT fr

om in

dent

atio

n te

sts

(N/m

m2 ) Tensile strength

Good agreement with results from tensile test

19

“Metallic materials — Measurement of mechanical properties by an instrumented indentation test

— Indentation tensile properties”

Korean Agency for Technology and Standards, Ministry of Knowledge Economy

ISO

- ISO TC164 SC3 working group

- 7 delegates (Korea, US, UK, Germany, Japan, China, Luxemburg) and 12 members

- *Convenor : Dongil Kwon (Korea)*Members : C. Ullner (Germany), N. Jennett (UK), E. Tobolski (US), S. Takagi (Japan),

J. Hahn (Korea), G. Bahng (Korea), A. Bushby (UK), H. Li (China), X. Zhoo (China), M. Griepeutrog (Germany), A. Riche (Luxembourg)

ISO/TR 29381 (2008)

International Standardization Works (ISO)

20

Applications

Oil & Gas Power Plant Railroad & Bridge

21

Residual Stress

22

0S LLL -=D

) L( S =

ht

ΔL

ΔL

LT

L0

Depth

LoadCompressive Tensile

Stressfree

LCTensile stress

Compressive stress

Indentation Load-Depth Curves

CLTL or

Vickersindenter

136

Basic Principle

23

Hydrostaticstress

deviatoric stress

sres

Core

Indenter

LS

sres

Plastic zone

Indentation Load : SL Residual Stress : ress

ht

ΔLLS

L0

Stressfree

Stress Interaction

24

Non-equibiaxial residual stress

xres

yresp

ss

=

÷÷÷÷÷÷

ø

ö

çççççç

è

æ

s+

s+

s+

xres

xres

xres

)p(

)p(

)p(

3100

03

10

003

1

÷÷÷÷÷÷

ø

ö

çççççç

è

æ

s+

-

s-

s-

xres

xres

xres

)p(

)p(

)p(

3100

03

120

003

2

÷÷÷

ø

ö

ççç

è

æ

ss

0000000

yres

xres

÷÷÷

ø

ö

ççç

è

æ

ss

0000000

xres

xres

p

hydrostatic stress deviatoric stress

xress

yress

x

y

z

Stress Ratio :

Stress Tensor

25

xresσ

3p)(1+

S

xres A

L1p)(1

3σ DY+

=

S

xres A

L1σ3

p)(1 DY

=+

÷÷ø

öççè

æ=

ss

= AreaContact,p xres

yres A S

Deviatoric stress along Z direction : Indentation stress :

intσ ÷÷ø

öççè

æY

=SA

ΔL1

where , = constraint factor (3.0)Y

L σxres Dµ

Residual Stress Indentation Load

yress

xress

Evaluation of Residual Stress by IIT

26

Method Merit Limitation

MechanicalMethods

Hole-Drilling

- Quantitative & mechanical analysis - Destructive

Saw-Cutting

PhysicalMethods

X-RayDiffraction

- Non-destructive- Only crystalline materials

- Sensitive to environmentNeutronDiffraction

Merit

IIT - Quantitative & mechanical analysis

- Non-destructive, can be used in field

- Any materials possible

- Microstructure not influenced

Merits of IIT

27

Comparison of Indentation vs Hole-drilling vs Saw-cutting results(API X65)

-200

-150

-100

-50

0

50

100

150

200

250

-50 0 50 100 150 200 250

Distance from welding center line (mm)

Res

idua

l str

ess

(MPa

)

Indentation

Hole-drilling

Saw-cutting

Evaluation of Residual Stress for API X65

28

¡ Place: LG Electronics Inc. (April 2006)¡ Object: Residual stress measurement for fine tube (silver brazing)¡ Material: Copper¡ System: Nano/Micro indentation system¡ Remark: Comparison of residual stress with normal and failure specimen

Schematic diagram

Out dia.=20mm,t=2mm

Out dia.=2mm, t=1mm

Silver brazing

Nano / Micro Indentation system

Analysis of Damaged Cause for Cu Pressure Vessel (1)

29

0 4 8 12 16 20 24 28-200

0

200

400

600

800

1000

Resi

dual

stre

ss (M

Pa)

Distance (mm)

Normal specimen Failure specimen

σh (Circumferential stress)

σa (Longitudinal stress)t

r

Resisting pressure: P

tpr

a 2=s

ah tpr ss 2==

Longitudinal stress:

Circumferential stress:

Failure

Indentation result

Max. residual stress

- Normal specimen: 423.48MPa

- Failure specimen: 859.89MPa

Failure to vertical direction of circumferential stress

Failure region

Analysis of Damaged Cause for Cu Pressure Vessel (2)

30

Advanced Indentation System

FRONTICS

Fast & Precise Solutions for Quality & ReliabilityGasan-dong, Geumcheon-gu, Seoul, KoreaTEL : 82-2-884-8025 http://www.FRONTICS.com

31

- Nondestructive

- Tensile properties, residual stress, fracture toughness

- Portable indentation system

- In-field / in-situ

- Local properties

- Automatic testing procedure and analysis

Wireless module LCD panel Portable battery Spherical Indenter

Easy & Simple

Advanced Indentation System (AIS)

32

AIS CompactSpecifications

Applications- Oil & Gas pipeline

- Power plant and pressure vessel

- Weld joint

- Industrial facilities

Load

Stroke

Size

Weight

100 kgf

10 mm

295×80×80 mm

3.5 kg

33

Micro-AIS

Applications

- Hard material coatings

- Protective coatings on glass

- Soil-resistant coatings

- Coatings of PC hard disks and CDs

- Thin paint coatings

Maximum

Resolution

Max. indent

Resolution

Load

Depth

2000 gf

100 mgf

15 um

10 nm

Specifications

34

Applications

- Nano-structured materials

- MEMS/NEMS

- Coating & Thin film

- Multiphase system

- Nanoimprint

Maximum

Resolution

Max. indent

Resolution

Load

Depth

25 mgf (250 mN)

35 μgf (0.35 nN)

2 um

0.05 nm

Specifications

Nano-AIS

SIDT ferrite

2nd phaseCoarse ferrite

Multiphase system

Beam bendingMultilayer system

Thin film MEMS devices

Electronic polymers

35

Applications

36

Fig. 90° Elbow Type (Weld /HAZ /Base)

(Contact points)(Chain System)

¡ Place: Kori nuclear power plant (January, 2002)¡ Object: Kori No.1 main cooling water line of nuclear power plant (Dia:12 in)¡ Condition: Operating Temperature: 60℃,/90° pipe of elbow type ¡ Material: ASTM A106 B (base metal), AWS E7016(weld metal)¡ Attachment: Chain system¡ Remarks: Mechanical Properties of base material, weldment and HAZ for main cooling

water line of nuclear plant aged more than 20 years

Welded Joint

37

Testing spots

#2

#9

•AWS E7016: Y(410MPa), UTS(530MPa) All-weld-metal tensile test

•ASTM A106B(min. spec.): Y(240MPa), UTS(415MPa), El(27%)

•ASTM A106B(real value): Y(300~360MPa), UTS(480~510MPa)

<Ref>

No. Y UTS n K Position

2 359 546 0.173 793.5 BASE

3 398 529 0.127 712.6 HAZ

4 412 576 0.144 797.9 WELD

5 433 526 0.093 664.6 WELD

6 369 583 0.184 862.2 WELD

7 362 549 0.171 795.7 HAZ

8 367 517 0.146 719.9 HAZ

9 321 508 0.185 751 BASE

Welded Joint

38

Fig. API X65 (Natural Gas Line)

Zoom

¡ Place: GE Power System (May, 2003)¡ Object: Natural Gas Line (Mexico Guadalajara)¡ Condition: Evaluation of tensile properties of underground pipeline¡ Material: API X42, X52, X60¡ Attachment: Curvature magnet system¡ Remark: Evaluation of tensile properties of pipeline of removed coating material

Oil & Gas

39

¡ Place: Casper, WY, US – Shell (August, 2007)¡ Object: 7.625 inch Freeze Tubes¡ Condition: Non-destructive Yield Testing of 7.625 inch Freeze Tubes¡ Attachment: U-block system¡ Remarks: Evaluation of yield strength for oil & gas-pipeline (Casper, WY, US) in Shell

Sample

Attachment

Testing position

Oil & Gas

40

Yield strength of different heats

0

5

10

15

20

25

30

35

40

45

Heater number

Yie

ld s

tren

gth

(Ksi

)

Mill test NDE section 1 NED section 2NDE section 3 NDE section 11 NDE section 12

Limited

Oil & Gas

41

¡ Place: Korea Gas Corporation (December, 2001)¡ Object: Testing of weld specimen for API 5L¡ Condition: Evaluation of tensile properties of micro-region at welding depth¡ Material: API 5L X65 [parts of pipeline at 30 in]¡ Attachment: Micro-positioning stage¡ Remark: Sample test of weldment cross-section

Fig. Lab scale application (Micro-positioning stage)

(Butt weld specimen) (Schematic diagram)

Oil & Gas

42

20mm

• The different hardness values between fine-grained and coarse ferrite phases

• Hard 2nd phase

Hot Rolling & Accelerated Cooling ( a + M )

SIDTF Cooling ferrite 2nd phase

SIDT ferrite

Coarse ferrite 2nd phase

H (GPa) 2.92 2.01 5.74

Multi-Phase Material

43

Standardizations & Activities

44

Standards& Codes

ISO

KSASME

ASTM• ISO/TC164 SC3 working group, Convener

(2003~2008)

• ISO/TR 29381, Evaluation of tensile properties(2008)

• ASTM A01/E07/E08/E28/E41, Committee member

• BPV II & SC-II SG-IMS, Committee member

• BPV IV, working item (in progress)

• KS B 0950, Evaluation of tensile properties(2002)

• KS B 0951, Evaluation of residual stress(2005)

Works related to Standardization

45

World Standards Day 2009A Red Strip Order of Service Merit, World Standards Day (October 14, 2009)

46

University of CambridgeIIW1 (1996)IIW2 (2001)IIW3 (2007)

Seoul National UniversityChair: Prof. Dongil Kwon

IIW4 (July 3-8, 2011)

International Indentation Workshop (IIW):Most oldest and reputational international conference in indentation and related research

Organization of Conferences

4747/30