CTOD Evaluation of API X80MO PSL2 TMCP Steel Welded Joints Used in Offshore Structures Based on API RP 2Z

Offshore structures and equipment, used both for oil extraction and wind power generation, are constantly exposed to extreme application conditions, such as low temperatures, corrosion, and cyclic loading. Thus, to ensure the integrity of such components, the use of materials with excellent mechanical properties combined with good weldability is required. In this sense, the main committees, institutes, and normative societies have created pre-qualifications, codes, and programs to evaluate and certify the weldability of steels applied in the offshore industry. API RP 2Z prequalification is one such standard that is designed to ensure that steels developed for these applications have excellent fracture toughness in the heat affected zone (HAZ). In this context, the effect of heat input on the HAZ toughness of welded joints of API X80MO steel plates was evaluated, using the CTOD (Crack Tip Opening Displacement) parameter. It was found that this steel, of 37 mm thickness, welded with heat inputs of 0.8 and 4.5 kJ/mm, presented weldability characteristics and fracture toughness behavior suitable for API RP 2Z standard specification. Therefore, API X80MO steel plates, produced by controlled rolling followed by accelerated cooling, is an option for application in the construction of offshore structures and components.