integrity assessment of dissimilar metal weld s

Bay Zoltán Foundation for Applied Reseach

Institute for Logistics and Production Systems BAY-LOGI

Integrity Assessment of Dissimilar Metal Welds

BAY-LOGI

1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND COMPONENTS”

Szabolcs Szávai Dr. Gyöngyvér B. Lenkey



EU5 ADIMEW project’s objectives

Evaluation of conservatism and accuracy of structural integrity assessment methods applied in the European nuclear industry

Study of the behaviour of circumferential surface defect in a dissimilar metal weld

Perform a unique four point bending test of a real size welded structure with crack like defect with normal operation condition



BAY-LOGI acitivities in the project Analysis of the effect of notch radius and its

position in the buttering on the structural behaviors

Study the effect of the notch radius on fracture toughness

Study the effect of the defect distance from the fusion line on fracture toughness

Post test modelling of a real size mock-up with crack like defect in the dissimilar weld



Dissimilar metal weld with crack like deffect



Fracture toughness determination Felrakóhegesztés

ER Ni Cr 3 Elektródával

Specimen. No. 2.

0

50

100

150

200

250

300

350

400

0,000 0,500 1,000 1,500 2,000 2,500Da-corr, mm

J, k

N/m

CT 25T=300 °C



Experimental results

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250 300 350

T, °C

J-IC

, kN

/m

r=0.2; d=2

r=0.1; d=2

r=0.2; d=1

r=0.2; d=2



Conclusions from the test results

The lower toughness value was obtained when the defect was closer to the fusion line (appr. 130 kN/m)

When the defect was farther from the fusion line, the toughness increased significantly(appr. 290 kN/m)

For sharper defect the toughness was lower (appr. 240 kN/m)



FE analysis on CT specimen with DMW

To study:– the effect of defect tip radius– the effect of the distance of the defect from the

fusion line– the effect of material properties– comparison of notched and pre-cracked

specimens



FEM analysis of CT specimen

StressCheck 6.1

60

25

50

62,5

10

19

308 L; WM

A 508

s

mm

pre-craced nothed

R

mm



Anyagok valódi feszültség-alakváltozás diagrammja, 300 °C (VTT_2)

0

100

200

300

400

500

600

700

800

900

1000

1100

0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8Eps_p

Seq

(M

Pa)

A508, 300°C_VTT2

316L, 300°C_VTT2

WM, 300°C_VTT2

B

True strain-stress cures, 300°C (VTT)



Stress and strain distribution in the specimen (F=60kN)

RyWM

RyA508



Effect of the notch geometry on the CMOD and the strain at the tip

0.000

0.001

0.002

0 10000 20000 30000 40000

Terhelés [N]

CM

OD

[m

]

Előrepesztett

R=0,1mm

R=0,2mm

Mért; R=0,2 mm-re

Eeq(max)-Terhelés; s=2 mm

0

1

2

3

4

5

6

7

8

9

10

0 10000 20000 30000 40000 50000 60000

Terhelés [kN]

Eeq

Előrepesztett

R=0,1 mm

R=0,2 mm

R=0,5 mm

COD-Load(pre-cracked specimen)

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0 10000 20000 30000 40000 50000 60000

Load [kN]

CO

D [

m]

s=0,5 mm

Fusion-Crack

s=2 mm

A508

WM

pre-cracked

pre-cracked

Load

Load

Load



Conclusions after the FE analysis of CT specimens

the effect of defect tip radius and defect distance on the CMOD values is small

the effect of material properties (i.e. yield stress) on CMOD values is stronger

the effect of defect tip radius on the stress-strain field at the notch tip is significant the effect on the failure load can be significant



Real size specimen for four point bending test

1 - Austenitic base metal 316 L, 2 - Ferritic base metal A 508, 3 - Dissimilar metal weld 308 L WM, 4 - Prolongation arms (E=206 Gpa, =0.3), 5 - Weld connecting austenitic base metal to prolongation

arm, 6 - Weld connecting ferritic base metal to prolongation arm (E=206 Gpa, =0.3)



Specimen and the project team



Test installation at EDF

Outer span : 7m

Inner span : 3m

Maximal load per ram : 2000 kN Maximal ram displacement : 1 m

D

Heating Collars

Heating internal Devices



Ram displacement without downloads

0

20

40

60

80

100

120

140

160

180

0 3 6 9 12 15 18 21 24

Steps

Ram

dis

pla

cem

ent

[mm

]

DV1

DV2

3000

7000

d=285mm

Pulling collars

Notch Support collar Support collar

Loads and constrains



Temperature distribution along the pipe

-

50

100

150

200

250

300

-5000 -4000 -3000 -2000 -1000 0 1000 2000 3000 4000 5000

Position on the mock-up (mm)

Te

mp

era

ture

s (

°C)

External - Bottom

External - Top

Mock-up 300°C arms



Post test analysis of the real size four point bending test

the muck-up is 300 °C the extension arms are approximately at

environmental temperature The crack like defect was shifted from the symmetry

plane with D=285 mm offset (due to the ram displacement control instead of the force control)

The supports were modelled as rigid constrains The elongations of the pulling parts were take into

consideration by application of spring elements in the Fem model



FEM model and the calculated stress distribution

CMOD mérés, 10 mm-rel a felület

felett

Elemszám: 35157 Csomópontszám: 42131



Glue of the different size meshes



Measured and calculated displacement-load-moment-CMOD curves

Measured and Calculated Ram Displacement-Force Curves

0

200

400

600

800

1000

1200

1400

0 50 100 150

Ram Displacement [mm]

Ram

Fo

rce

[kN

]

FV1_FE

FV2_FE

FV1_Measured

FV2_Measured

Measured and Calculated CMOD-Force Curves

0

200

400

600

800

1000

1200

1400

0 0.5 1 1.5 2 2.5 3 3.5

CMOD O3 [mm]

Ram

Fo

rce

[kN

]

FV1_FE

FV2_FE

FV1_Measured

FV2_Measured

Measured and Calculated CMOD-Moment curves

00.20.40.60.8

11.21.41.61.8

22.2

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

CMOD O3 [mm]

Mo

men

t [M

Nm

]

CMOD_Moment

Measured



Round-robin results

0

200

400

600

800

1000

1200

0 25 50 75 100 125 150

Dugattyú elmozdulás, mm

Te

rhe

lő e

rő (

du

ga

ttyú

kon

), k

N

FV1 (kN)

FV2 (kN)

FANP2-FV1

FANP2-FV2

GRS FV1

GRS FV2

NRG1-FV1

NRG1 FV2

VUJE FV1

VUJE FV2

BZLOGI-FV1

BZLOGI-FV2



Summary and conclusions – post test

Due to the complex geometry huge number of elements and nodes were generated

Results have been compared with the test at some selected points

Ram-force - CMOD values were in good agreement with the calculation



General Conclusions

The structure modeling gives appropriate results for further evaluations

For operational safety assessments the fracture mechanical tests are essential

For the validations of the calculation methods structural tests needed

integrity assessment of dissimilar metal weld s

Documents