PSI - Issue 13

Luka Grubiša et al. / Procedia Structural Integrity 13 (2018) 430–437 Luka Grubiša, Darko Bajić, Tomaž Vuherer/ Structural Integrity Procedia 00 (2018) 000 – 000

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and energy for propagation is almost 60% higher in weld metal than in HAZ microstructure. The ratio of the energies for initiation and propagation at WM is more convenient than in HAZ microstructure. Specimens for fracture mechanics tests were taken in L-T direction from the weld joint with the notch in WM and HAZ materials. SENB specimens were machined according to ASTM E1820-15a standard (Fig. 6). Results of the testing are shown in Fig. 13 and Fig. 14, where force versus crack mouth opening displacement diagrams (F – CMOD) are shown. Although the tests did not meet all the requirements according to ASTM E1820-15a standard, the test were done by intention to compare behaviour of material when crack is present in material in case of the weld metal and HAZ microstructure. Because not all criteria has been fulfil, the critical J and K JIC were unable to determine, so measured values are noted as the J Q and K Q .

Chart Applied Load vs. Crack Mouth Opening Displacement

1000.0 1200.0 1400.0 1600.0

0.0 200.0 400.0 600.0 800.0

Applied load P; [N]

0.00

0.10

0.20

0.30

0.40

0.50

0.60

Measured crack mouth opening displacement CMOD; [mm]

Fig. 13. F-CMOD diagrams for weld metal material

Chart Applied Load vs. Crack Mouth Opening Displacement

1000.0 1200.0 1400.0 1600.0 1800.0 2000.0

0.0 200.0 400.0 600.0 800.0

Applied load P; [N]

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Measured crack mouth opening displacement CMOD; [mm]

Fig. 14. F-CMOD diagrams for HAZ microstructure

Measured J -critical integral ( J Q ), critical crack tip opening displacement ( δ Q ) and fracture toughness K Q are shown in Table 6. The J integral determined in HAZ microstructure is higher than in weld metal, but values do not differ too much.