Improvement of strength and toughness: The effect on the weldability of high-strength steels used in offshore structures

Abstract

The effect of strength and toughness on the weldability of high-strength steels is very vital consideration in the offshore oil and gas industries. Improved impact toughness of high-strength steels in offshore structures enables viable exploitation of hydrocarbons in technologically challenging conditions. This article reviews improvements in the weldability and impact toughness of high-strength steels. Steels with high strength are associated with high carbon content and addition of alloying elements as they induce hardness which leads to a higher risk of brittle fracture and hydrogen-induced cracking needs. The combination of high strength with high toughness was studied by examining the toughening mechanism of thermomechanical-controlled processing steels, which have higher strength than conventional steel plates but meet the conflicting requirements of strength, toughness and weldability. The thermomechanical-controlled processing production process entails controlled rolling process combined with accelerated cooling or direct quenching to ensure stable mechanical properties of thermomechanical-controlled processing products in welded constructions. It is concluded that due to their very fine grain size and refined heat-affected zone structure, thermomechanical-controlled processing steels can be an effective cost-saving means for fabrication of offshore structures, particularly in shipbuilding, offshore platforms and pipelines for high-operating pressures.