Integrity Assessment of Dissimilar Metal Weld s

1. BAY-LOGI 1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND COMPONENTS” Integrity Assessment of Dissimilar Metal Welds SzabolcsSzávai Dr. Gyöngyvér B. Lenkey

2. 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

3. 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

4. Dissimilar metal weld with crack like deffect

5. Fracture toughness determination CT25 T=300 °C

6. Experimental results

7. 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)

8. 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

9. 19 s mm Æ 10 25 62,5 50 308 L; WM pre-craced nothed 60 A 508 R mm FEM analysis of CT specimen StressCheck 6.1

10. True strain-stress cures, 300°C (VTT)

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

12. Effect of the notch geometry on the CMOD and the strain at the tip pre-cracked Load Load pre-cracked Load

13. 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

14. 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)

15. Specimen and the project team

16. Test installation at EDF

17. Loads and constrains

18. Temperature distribution along the pipe arms Mock-up 300°C

19. 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

20. FEM model and the calculated stress distribution

21. Glue of the different size meshes

22. Measured and calculated displacement-load-moment-CMOD curves

23. Round-robin results

24. 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

25. 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 methodsstructural tests needed