PSI - Issue 42

Tadeu Messias Donizete Borba et al. / Procedia Structural Integrity 42 (2022) 276–283 Tadeu Messias Donizete Borba / Structural Integrity Procedia 00 (2019) 000 – 000

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mm, tested at -10 ºC, are required. The API 1104 standard recommends values greater than or equal to 0.10 mm, tested at the same temperature, and in the case of the Petrobras N-1678 standard, 0.25 mm at the same temperature. Thus, through the results presented, it is possible to conclude that API X80MO steel, with a thickness of 37 mm, welded with heat inputs of 0.8 and 4.5 kJ/mm, presents adequate weldability characteristics as it presents CTOD results valid and higher than the minimum specified by these standards. In addition, it can be considered that the welding procedure and consumables used are excellent alternative for joining API X80MO steel to meet the requirements of the API RP 2Z standard.

Table 6. CTOD results for valid CGHAZ specimens. FCAW Specimens

CTOD (mm)

SAW Specimens CGSW1- valid CGSW2- valid CGSW3- valid CGSW4- valid CGSW5- valid CGSW6- valid CGSW7 - valid CGSW8 - invalid

CTOD (mm)

CGFW1- valid CGFW2- valid CGFW3- valid CGFW4- valid CGFW5- valid CGFW6- valid CGFW7- valid CGFW8- valid

0.54 0.53 0.67 0.96 0.50 0.37 0.48 0.68

2.09 0.43 2.16 1.67 1.19 0.94 0.73 2.27

Mean

0.59 ± 0.18

Mean

1.32 ± 0.67

Fig. 4. Relation between the fraction of the CGHAZ region sampled by the notch and the CTOD value for the specimens close to the fusion line.

4 - Conclusion In this study, the weldability characteristics of the API-5L-12-X80M-PSL2 steel were evaluated according to the criteria stipulated in the API RP 2Z standard. For this purpose, procedures aimed at welding with low and high heat input were used. For the first condition, the arc process with gas shielding and the addition of Dual Shield 55 tubular wire (AWS A5.29 E91T1-Ni1M) was used. As for the high heat input condition, the welding process used was the submerged arc with the combination wire OK Autrod 13.40 and OK Flux 10.62. It was found that welding with low heat input was the most deleterious for fracture toughness as it provided a greater fraction of fragile regions along the notch of the CTOD specimens. The lowest and highest individual CTOD values obtained in this condition, were 0.37 and 0.96 mm, respectively. For the welded joints with the highest heat input, the best toughness results observed were attributed to a smaller sampling of the coarse-grained region of the HAZ along the notch of CTOD, which presents a greater resistance to fracture propagation. For this condition, the lowest and highest individual CTOD values obtained were 0.43 and 2.16 mm, respectively. Through the results obtained, it is possible to conclude that API-5L-12-X80M-PSL2 steel, of 37 mm thickness, welded with heat inputs of 0.8 and 4.5 kJ/mm, presents adequate weldability characteristics as it exhibits